Updated July 31, 2026: Heat pump outdoor-unit behaviour varies by manufacturer, equipment type, operating mode and control strategy. A temporarily quiet outdoor unit does not automatically indicate a failed compressor or motor.
If your heat pump outdoor unit is not running, first determine whether the system is actually calling for heating or cooling and whether the entire outdoor unit is inactive or only the outdoor fan has stopped. A heat pump can pause normally after reaching setpoint, during a protective restart delay or during certain control sequences. During winter defrost, the outdoor fan may stop while the compressor continues operating.
If the home is not heating or cooling and the outdoor unit remains inactive, safe homeowner checks include thermostat settings, accessible filters, visible fault codes, the obvious state of the electrical breaker and signs of ice, damage or debris around the equipment.
Do not open the outdoor cabinet, remove electrical covers, test capacitors or inverter components, measure live voltage, bypass safety controls or open the refrigeration system.
Why Is My Heat Pump Outdoor Unit Not Running?
There are two broad possibilities:
- The heat pump is intentionally not operating.
- A fault is preventing outdoor operation.
Normal Possibilities Include:
- The thermostat has reached setpoint.
- There is no current heating or cooling demand.
- A compressor protection delay is active after startup or power interruption.
- The equipment is between variable-capacity operating cycles.
- A dual-fuel system is intentionally using the furnace instead.
Possible Faults Include:
- No outdoor electrical power
- Thermostat or control fault
- Communication problem
- Outdoor control-board fault
- Inverter fault
- Compressor protection
- Compressor failure
- Outdoor fan fault
- Sensor fault
- Refrigeration-system protection
Do Not Diagnose a Compressor From Silence
A compressor that is not operating can be:
- Intentionally commanded off
- Waiting through a protective delay
- Locked out because of another fault
- Missing electrical power
- Actually failed
The diagnostic task is determining which condition applies.
Outdoor Fan Stopped vs Entire Outdoor Unit Stopped
This distinction is essential.
Outdoor Fan Stopped
You may still hear or feel evidence that the compressor is operating even though the outdoor fan is stationary.
This can occur normally during defrost on many heat pumps.
Entire Outdoor Unit Stopped
The outdoor fan and compressor are both inactive.
Possible explanations include:
- No current demand
- Restart delay
- Loss of power
- Control fault
- Communication failure
- Protective shutdown
Why the Difference Matters
If only the fan is stopped, diagnosis may focus on:
- Defrost state
- Fan motor
- Fan electronics
- Fan control
If the entire outdoor unit is inactive, a system-level power or control issue becomes more relevant.
When Can a Heat Pump Outdoor Unit Normally Stop?
The Thermostat Is Satisfied
Once the room reaches the requested temperature, the heat pump may reduce output or stop according to its control strategy.
Restart Delay
Heat pumps can use compressor-protection delays after:
- Power interruption
- Mode change
- System shutdown
- Rapid thermostat changes
Depending on the equipment, this delay may last several minutes.
Variable-Speed Operation
Modern inverter systems can operate very quietly at low capacity.
Before assuming the outdoor unit is completely off, observe it safely for several minutes without removing covers or approaching moving components.
Dual-Fuel Operation
In some hybrid systems, controls can intentionally stop heat-pump operation and use the furnace instead.
Defrost Is Different
During defrost, the outdoor fan may stop while the compressor continues operating.
Do not interpret a stationary fan during a brief winter defrost sequence as proof that the entire outdoor unit has stopped.
1. The Thermostat Setpoint Is Already Satisfied
The simplest explanation is often that the heat pump is not being asked to run.
Check:
- Current room temperature
- Heating or cooling setpoint
- Thermostat schedule
- Occupied or Away mode
Example
If the home is 21°C and Heat is set to 20°C, the outdoor unit should not be expected to start merely because the thermostat display is on.
Variable Systems Can Behave Differently
Some equipment may:
- Slow substantially
- Cycle off
- Maintain a very small operating output
depending on system design.
2. The Thermostat Is in the Wrong Mode
A thermostat or ductless controller can be powered and functional while requesting the wrong operating mode.
Check for:
- Heat during winter
- Cool during summer
- Fan-only mode
- Dry mode on ductless equipment
- Auto mode behaviour
Fan Mode Does Not Necessarily Start the Outdoor Unit
On a central system, selecting Fan can operate the indoor blower without requiring compressor operation.
Multi-Zone Systems Can Add Complexity
Some conventional multi-zone heat pumps cannot provide heating to one indoor unit while another connected indoor unit requests cooling.
A conflicting mode request can leave one or more zones waiting.
3. A Normal Startup or Restart Delay Is Active
A heat pump compressor may not restart immediately after it stops.
Why?
Protective delays help prevent rapid compressor cycling.
A Delay Can Follow:
- Power restoration
- Thermostat adjustment
- Changing Heat to Cool
- Changing Cool to Heat
- Recent compressor shutdown
What Should the Homeowner Do?
After confirming the thermostat setting, give the system several minutes to respond.
Do Not Rapidly Cycle the Controls
Repeatedly switching operating modes can restart or extend protective timing and make diagnosis harder.
4. The Thermostat or Controller Has a Fault
The outdoor unit depends on the control system to know when heating or cooling is required.
Possible Problems Include:
- Thermostat fault
- Incorrect configuration
- Loose wiring
- Failed control output
- Communication problem
- Incorrect equipment setup
Signs Can Include:
- Thermostat shows a demand but nothing starts outside
- Heat works but cooling does not
- Cooling works but heating does not
- AUX Heat operates without heat-pump operation
Do Not Replace the Thermostat Based on Guesswork
The technician should confirm whether the thermostat is actually sending the expected command before condemning it.
5. The Outdoor Unit Has Lost Electrical Power
Indoor and outdoor heat pump components can have separate electrical supplies.
Therefore:
The indoor blower, thermostat or ductless display being powered does not prove that the outdoor unit has electrical power.
Possible Causes Include:
- Tripped breaker
- Disconnect problem
- Loose electrical connection
- Damaged wiring
- Failed electrical component
- Internal equipment protection
Safe Homeowner Check
You can visually check the normal labelled breaker position without removing the electrical-panel cover.
Repeated Trip?
Do not repeatedly reset the breaker.
Repeated operation of electrical protection can indicate:
- Compressor fault
- Fan fault
- Inverter problem
- Wiring problem
- Another electrical fault
Outdoor Disconnect
Do not open or dismantle the disconnect to diagnose the heat pump. Electrical testing belongs to qualified personnel.
6. A Low-Voltage Power or Control Problem Exists
Central heat pumps often rely on control voltage in addition to the outdoor unit’s main electrical supply.
Possible Problems Include:
- Failed transformer
- Control fuse
- Damaged thermostat wiring
- Loose terminal
- Control-board problem
Symptoms Can Be Misleading
The thermostat may appear normal if it uses:
- Battery power
- A different control-power source
Do Not Open Equipment to Find the Fuse
Control circuits can be located inside cabinets containing hazardous electrical components.
7. Indoor-Outdoor Communication Has Failed
Many modern heat pumps use digital communication between indoor and outdoor equipment.
This Is Common In:
- Ductless mini-splits
- Multi-zone systems
- Variable-capacity central systems
- Communicating HVAC systems
A Communication Fault Can Leave:
- Indoor unit powered
- Controller display active
- Outdoor unit inactive
Possible Causes Include:
- Incorrect wiring
- Loose connection
- Damaged communication cable
- Indoor board fault
- Outdoor board fault
- Power problem
Record the Fault Code
Do not immediately clear the display or cycle the breaker repeatedly.
A photograph of the code can be useful when the fault is intermittent.
8. The Outdoor Control Board Has a Fault
The outdoor control board coordinates major equipment functions.
Depending on the Heat Pump, It Can Be Involved With:
- Compressor operation
- Outdoor fan operation
- Defrost
- Sensors
- Communication
- Protection logic
A Board Fault Can Make the Entire Outdoor Unit Appear Dead
But board replacement should follow diagnosis.
Other Problems Can Mimic a Failed Board
- Missing supply power
- Low-voltage problem
- Communication fault
- Sensor fault
- Inverter fault
Fault Code Does Not Always Equal Failed Board
Service documentation and electrical testing are needed to identify the actual cause.
9. The Inverter or Compressor Drive Has a Fault
Variable-capacity heat pumps often use inverter electronics to control compressor operation.
An Inverter Fault Can Cause:
- Outdoor unit not starting
- Compressor not starting
- Intermittent operation
- Protective shutdown
- Fault codes
Do Not Apply Old Single-Stage Troubleshooting Rules
Modern inverter systems can contain:
- Power electronics
- DC bus voltage
- Electronic motor control
- Digital diagnostics
This Is Not Homeowner Electrical Work
Do not remove covers or test:
- Inverter boards
- Capacitors
- Compressor terminals
- Live electrical circuits
10. Compressor Protection or Lockout Is Active
A compressor can be physically capable of running while the control system intentionally prevents operation.
Protection Can Respond to Conditions Such As:
- Abnormal temperature
- Abnormal electrical condition
- Refrigeration-system condition
- Repeated fault
- Rapid restart attempt
Some Faults Clear Automatically
Others can remain stored or locked out until:
- Conditions return to normal
- The system completes a control sequence
- Professional diagnosis addresses the cause
Do Not Defeat Protection
A system refusing to operate can be inconvenient, but protective controls can prevent additional equipment damage.
11. The Compressor Has a Fault
Compressor failure is one possible cause, but it should not be the first assumption.
Possible Compressor Problems Include:
- Electrical winding fault
- Mechanical failure
- Internal protection
- Locked rotor on applicable equipment
- Inverter-compressor fault
Possible Symptoms Include:
- Outdoor fan operates but compressor does not
- System tries to start and faults
- Electrical protection operates
- Stored compressor fault code
- No heating or cooling capacity
Confirm the Failure Before Replacement
Power, controls, inverter operation and refrigeration conditions can all prevent a healthy compressor from running.
12. The Outdoor Fan System Has a Fault
A fan problem can sometimes cause the heat pump to stop or enter protection.
Possible Fan Problems Include:
- Fan motor failure
- Electronic motor-control failure
- Capacitor failure on applicable conventional motors
- Control-board fault
- Physical obstruction
- Ice contact
Important: A Stationary Fan Is Not Always a Failed Fan
During winter defrost, many heat pumps intentionally stop the outdoor fan while the compressor continues operating.
Outside Normal Defrost
If the compressor is operating but the required outdoor fan remains stationary, shut the system down and arrange service.
Do Not Spin the Fan Blade by Hand
The fan can start automatically, and manual movement does not safely identify the electrical or control fault.
13. A Sensor or Thermistor Has Failed
Modern heat pumps rely on temperature and other sensing inputs to decide:
- When to run
- How fast to run
- When to defrost
- When to stop for protection
Possible Sensors Include:
- Outdoor-air temperature sensor
- Coil temperature sensor
- Discharge temperature sensor
- Other manufacturer-specific sensors
A Sensor Fault Can Cause:
- Failure to start
- Unexpected shutdown
- Incorrect defrost behaviour
- Fault code
Do Not Bypass a Sensor
The technician should determine whether:
- The sensor reading is incorrect
- The wiring is faulty
- The system is responding to a genuine abnormal condition
14. Refrigeration Conditions Triggered Protection
The outdoor unit can stop because refrigeration-system operating conditions are outside an acceptable range.
Depending on Equipment Design, Possible Causes Can Include:
- Refrigerant leak
- Incorrect refrigerant charge
- Restricted refrigerant flow
- Indoor airflow problem
- Outdoor airflow problem
- Fan failure
- Sensor problem
Not Every Heat Pump Uses the Same Protection Hardware
Some systems use:
- Pressure switches
- Pressure transducers
- Temperature-based protection logic
- Manufacturer-specific control algorithms
Do Not Diagnose Refrigerant From an Inactive Outdoor Unit
Low refrigerant is only one possibility among many.
Do Not Add Refrigerant as a Test
The technician should establish whether the refrigeration system is actually abnormal and identify the underlying cause.
15. Ice, Airflow or Coil Conditions Are Causing Trouble
Outdoor airflow is essential to heat pump operation.
Possible Problems Include:
- Heavy persistent ice
- Snow blockage
- Debris around the coil
- Outdoor fan obstruction
- Dirty outdoor coil
Normal Frost Is Different
During heating in cold, damp weather, frost can form on the outdoor coil.
The system should periodically use defrost to clear normal accumulation.
Arrange Service When:
- Heavy ice remains and grows
- The fan strikes ice
- Defrost does not appear to clear the coil
- The home loses heating capacity
- The system repeatedly shuts down
Do Not Chip the Coil Free
Tools can damage:
- Coil fins
- Refrigerant tubing
- Fan blades
16. Wiring, Configuration or System Integration Is Wrong
This is particularly relevant when the problem began after:
- New installation
- Thermostat replacement
- Electrical work
- Control-board replacement
- Furnace replacement
- Recent HVAC service
Possible Issues Include:
- Incorrect thermostat configuration
- Wiring error
- Incorrect dip-switch or software configuration
- Wrong indoor-outdoor equipment setup
- Dual-fuel control error
- Communication wiring issue
New Equipment Can Have Setup Problems
Do not assume a newly installed heat pump has a defective compressor when the actual problem may be controls, configuration, wiring or commissioning.
Tell the Technician What Changed
If the outdoor unit stopped after another contractor worked on the thermostat, electrical panel, furnace or controls, that timing is valuable diagnostic information.
Safe Homeowner Checks When the Outdoor Unit Is Not Running
1. Confirm an Actual Heating or Cooling Demand
Check the room temperature, setpoint, Heat or Cool mode and schedule.
2. Wait Several Minutes
After a recent control or power change, allow time for normal compressor-protection delays.
3. Check for Fault Codes
Look at the thermostat, ductless controller or accessible equipment display. Take a photograph before changing settings.
4. Check the Filter
For systems with homeowner-serviceable filters, clean or replace them according to equipment instructions.
5. Check Indoor Airflow
Note whether the central blower is running, air is coming from registers or ductless indoor fans are operating.
6. Look at the Outdoor Unit From a Safe Position
Check for heavy ice, snow blockage, debris, physical damage or visible fan obstruction.
7. Check the Obvious Breaker Position
Without removing electrical-panel covers, note whether a clearly labelled heat-pump breaker appears tripped.
8. Note Which Components Still Work
Examples include indoor blower operation, AUX Heat, gas furnace operation, multiple ductless zones or only one affected zone.
9. Note What Happened Immediately Before the Failure
Power outages, breaker trips, thermostat replacement, cold weather, icing and recent service work can all provide useful diagnostic context.
What Homeowners Should Not Do
- Do not open the outdoor electrical cabinet.
- Do not test capacitors, inverter boards or compressor terminals.
- Do not probe live electrical circuits.
- Do not repeatedly reset a breaker.
- Do not bypass pressure, temperature or safety controls.
- Do not add refrigerant as a test.
- Do not force the outdoor fan to spin.
- Do not chip ice from the coil.
When Should You Shut the Heat Pump Off?
Smoke or Burning Electrical Odour
Shut the system off and arrange service.
Visible Arcing or Electrical Damage
Do not operate the equipment.
Repeated Breaker Trips
Do not keep resetting the breaker.
Severe Grinding or Mechanical Impact
Stop operation to reduce the risk of additional damage.
Fan Blade Striking Ice or Another Object
Shut the unit down.
Compressor Appears to Run While Required Outdoor Fan Does Not
Outside normal defrost behaviour, stop operation and arrange professional diagnosis.
Outdoor Unit Is Physically Damaged
Damage from impact, construction or severe weather should be inspected before normal operation resumes.
Ducted Heat Pump Outdoor Unit Not Running
A central ducted system can continue moving indoor air even when the outdoor heat pump is unavailable.
Indoor Blower Running Does Not Prove the Heat Pump Is Heating
The blower can operate with Fan mode, electric auxiliary heat or during some control sequences.
Full-Electric System
If the outdoor heat pump is unavailable, the controls may use electric resistance backup where installed and configured to do so.
This Can Hide the Failure
The home may remain warm while electricity consumption rises because resistance heat is doing more of the work.
Check for AUX Indication
Unexpected prolonged AUX operation during conditions where the heat pump would normally operate can justify service.
Ductless Heat Pump Outdoor Unit Not Running
A ductless indoor head can remain powered even when the outdoor unit cannot operate.
You May See:
- Display still illuminated
- Remote still responding
- Indoor fan operating briefly
- Fault code appearing
- No heating or cooling output
Possible Causes Include:
- Restart delay
- Communication fault
- Outdoor power failure
- Inverter fault
- Sensor fault
- Compressor protection
Do Not Judge From Sound Alone
Inverter outdoor units can operate quietly at low speed.
Check the Controller for Error Information
Record any code before power is cycled.
Multi-Zone Heat Pump Outdoor Unit Not Running
A multi-zone outdoor unit serves several indoor units.
If Every Zone Loses Heating or Cooling
A shared outdoor-system issue becomes more likely, including outdoor power, control board, inverter, compressor, shared communication fault or system-level protection.
If Only One Zone Has a Problem
The shared outdoor unit may be functioning normally. A local indoor-unit, sensor, fan, communication or zone-control issue may be more likely.
Check Operating Modes
Some multi-zone systems cannot satisfy simultaneous Heat and Cool demands across connected indoor units.
Dual-Fuel Heat Pump Outdoor Unit Not Running
In a dual-fuel system, the gas furnace may operate while the outdoor heat pump is intentionally off.
This Can Be Normal
Depending on control design, the furnace can run based on outdoor conditions, thermostat logic, configured changeover settings or a heat-pump fault.
Unexpected Furnace Operation Deserves Review
If the system now relies continuously on the furnace under conditions where the heat pump previously operated, investigate heat-pump faults, thermostat configuration, outdoor sensors and control changes.
How Does a Technician Diagnose a Heat Pump Outdoor Unit That Is Not Running?
1. Reproduce the Complaint
Confirm heating or cooling mode, setpoint, indoor temperature and which components are operating.
2. Review Current and Stored Fault Codes
Intermittent failures can leave useful history even when the system is operating normally during the service visit.
3. Verify the Control Demand
Determine whether the outdoor unit is actually being commanded to operate.
4. Verify Electrical Supply
Qualified testing can confirm supply voltage, electrical protection, disconnect condition and connections.
5. Check Control Power and Communication
Depending on system design, evaluate low-voltage supply, communication wiring, thermostat signals and indoor-outdoor communication.
6. Evaluate Outdoor Controls and Inverter Electronics
Review the control board, drive or inverter, manufacturer diagnostics and protection history.
7. Evaluate Outdoor Fan and Compressor
Determine whether each component receives the expected command and electrical supply and operates as intended.
8. Check Sensors and Coil Conditions
Inspect the outdoor coil, ice, debris, fan obstruction and sensor readings.
9. Evaluate Refrigeration Operation When Appropriate
Once airflow, electrical operation and controls are understood, professional diagnosis may evaluate temperatures, pressures, refrigerant-system behaviour and manufacturer service data.
10. Identify the Cause Before Replacing Parts
The repair should address why the outdoor unit is not operating, not simply replace major components without confirmation.
Common Heat Pump Outdoor-Unit Repairs
The repair depends on the diagnosis.
Electrical Repairs Can Include:
- Wiring repair
- Connection repair
- Control component replacement
- Electrical protection issue
Control Repairs Can Include:
- Thermostat correction
- Configuration correction
- Sensor replacement
- Control-board replacement
- Communication repair
Fan Repairs Can Include:
- Fan motor
- Motor-control electronics
- Fan blade
- Obstruction or ice-related repair
Compressor or Inverter Repairs
These can be major repairs and deserve confirmation of failure, warranty, root cause and the condition of the remaining system.
Refrigeration Repairs
Where a refrigeration-system condition caused shutdown, the repair may involve leak repair, component repair, refrigeration testing, evacuation and charging as required.
Should You Repair or Replace a Heat Pump With an Inactive Outdoor Unit?
The fact that the outdoor unit will not start does not by itself justify replacement.
Repair Often Makes Sense When:
- The fault is isolated.
- The system is otherwise reliable.
- The equipment previously provided good comfort.
- Parts are available.
- Warranty applies.
- The compressor and coils remain healthy.
Replacement Deserves More Consideration When:
- The system has repeated major failures.
- Compressor failure is confirmed on older equipment.
- Inverter and refrigeration problems are occurring together.
- A major coil also leaks.
- Critical parts are obsolete.
- The system was poorly sized or installed from the beginning.
Do Not Use Silence as a Replacement Diagnosis
A failed sensor or control circuit can make an expensive outdoor unit appear completely inactive while much of the mechanical equipment remains serviceable.
Compare a Complete Replacement Project
If replacement is being considered, reassess heating load, cooling load, ductwork or zoning, electrical capacity, backup heat and equipment location rather than automatically replacing the old system with the same nominal size.
What Affects Heat Pump Outdoor-Unit Repair Cost?
There is no reliable universal cost range because “outdoor unit not running” describes a symptom rather than one repair.
Cost Can Depend On:
- Diagnostic time
- Electrical fault
- Control board
- Sensor
- Communication repair
- Fan motor
- Inverter or drive
- Compressor
- Refrigeration repair
- Parts availability
- Warranty
Bernoulli Diagnostic Appointment
The current diagnostic appointment charge for an existing heat pump is $135.
Repair labour, replacement parts, refrigerant and additional materials are separate.
Replacement Estimate
If diagnosis shows that replacement is more practical, new heat pump installation and replacement estimates are free.
How Can You Reduce Future Outdoor-Unit Problems?
Keep Outdoor Airflow Clear
Maintain appropriate manufacturer clearances from vegetation, stored objects, leaves and snow.
Keep Filters Maintained
Indoor airflow problems can affect the operation of the entire refrigeration system.
Do Not Ignore Persistent Ice
Normal winter frost should clear through defrost. Heavy persistent ice should be investigated.
Do Not Ignore Intermittent Fault Codes
Photograph them before they disappear.
Protect the Outdoor Unit From Physical Damage
Consider exposure to vehicles, falling objects, construction work and landscaping equipment.
Arrange Professional Maintenance
Natural Resources Canada currently recommends qualified annual heat pump maintenance and regular homeowner attention to filters and unobstructed airflow.
Heat Pump Outdoor-Unit Diagnosis in Metro Vancouver and Fraser Valley
Bernoulli Heating and Cooling provides heat pump troubleshooting across Metro Vancouver and Fraser Valley.
When an outdoor unit is not running, diagnosis can include system controls, power supply, communication, sensors, outdoor fan operation, inverter electronics, compressor operation, airflow, icing and refrigeration-system conditions as appropriate.
The current diagnostic appointment charge is $135. Repair labour, replacement parts, refrigerant and additional materials are separate.
New heat pump installation and replacement estimates are free.
Call 604-518-4438 or email heatingbernoulli@gmail.com.
If replacement becomes the better option, review Heat Pump Installation Burnaby.
Heat Pump Outdoor Unit Not Running: Frequently Asked Questions
Why is my heat pump outdoor unit not running?
Possible causes include no heating or cooling demand, normal restart delay, thermostat problems, loss of electrical power, communication faults, control-board problems, inverter faults, compressor protection, fan problems, sensor faults or refrigeration-system protection.
Is it normal for a heat pump outdoor unit to stop?
Yes. It can stop when the thermostat is satisfied, while waiting through a protective restart delay or according to the system’s normal control strategy.
How long should I wait before deciding the outdoor unit is not starting?
After confirming the correct mode and setpoint, wait several minutes because many systems use a compressor restart delay. Follow the equipment manual for the exact model.
Why does my thermostat say Heat but the outdoor unit is off?
The thermostat may not currently require heat, a delay may be active, backup heat may be operating or a control, power or outdoor-unit fault may exist.
Can the indoor blower run while the outdoor heat pump is off?
Yes. Fan mode, auxiliary heat and various control sequences can operate the indoor blower independently of the outdoor compressor.
Can AUX Heat run while the outdoor unit is off?
Yes, depending on system design and controls.
Why is AUX Heat running but the outdoor unit is not?
Possible reasons include normal control logic, outdoor lockout, heat-pump fault, thermostat configuration or a system operating in backup-only mode.
Will my house stay warm if the outdoor unit fails?
It may if the system has functioning electric backup heat, a dual-fuel furnace or another heating source.
Can Emergency Heat work with the outdoor unit off?
Yes on systems where Emergency Heat intentionally uses independent backup heating and disables normal outdoor heat-pump operation.
Does Emergency Heat fix the outdoor unit?
No. It can provide temporary heating while the heat-pump problem remains unresolved.
Can a gas furnace run while the heat pump outdoor unit is off?
Yes in a properly configured dual-fuel system.
Does the furnace running mean the heat pump is broken?
No. The system may intentionally use the furnace under certain control conditions.
Why is my outdoor fan not spinning?
The system may be in defrost, there may be no current operating demand or a fan, electrical or control fault may exist.
Is it normal for the outdoor fan to stop during defrost?
Yes. Many heat pumps intentionally stop the outdoor fan during defrost while the compressor continues operating.
Does the compressor keep running during defrost?
On many heat pumps, yes. The refrigeration cycle changes so heat can be directed toward the outdoor coil while the outdoor fan stops.
Is steam from the outdoor unit normal?
Visible water vapour during winter defrost can be normal as frost melts from the outdoor coil.
Why does the outdoor unit make a different sound during defrost?
The refrigeration cycle changes and fan behaviour can change, so temporary changes in sound can be normal.
How long does defrost last?
Duration varies by equipment and conditions. Follow the manufacturer documentation for the installed system rather than using a universal timer.
What if the outdoor fan never restarts after defrost?
Arrange service if normal heating does not resume or the fan remains stopped when it should be operating.
Is frost on the outdoor coil normal?
Some frost is normal during heating in cold, damp weather.
Is a completely iced outdoor unit normal?
Heavy persistent ice that does not clear normally deserves diagnosis.
Can snow stop the outdoor unit?
Snow can obstruct airflow or contribute to abnormal operating conditions when it accumulates around equipment.
Should I shovel snow away from the heat pump?
You can keep the surrounding airflow area clear without striking, opening or damaging the equipment. Follow manufacturer clearance guidance.
Can I pour hot water on an iced heat pump?
Do not use improvised thawing methods that can damage equipment or create additional ice. Persistent icing should be diagnosed.
Can I chip ice off the outdoor coil?
No. Tools can damage fins, refrigerant tubing or fan components.
Can a dirty outdoor coil stop the heat pump?
Severe airflow and heat-transfer problems can contribute to abnormal operation and protection conditions.
Can a dirty filter stop the outdoor unit?
Restricted indoor airflow can cause abnormal system conditions that may eventually result in protection or poor performance, depending on equipment design.
Can closed vents make the outdoor unit shut down?
Closing many vents can increase duct-system restriction and reduce airflow. Whether the system shuts down depends on the equipment and resulting operating conditions.
Can a thermostat cause the outdoor unit not to run?
Yes. Thermostat demand, configuration, wiring or failure can prevent normal outdoor operation.
Can thermostat batteries cause this problem?
On thermostats that depend on batteries for certain functions, weak batteries can affect operation. Follow the thermostat instructions.
Can replacing my thermostat stop the outdoor unit from working?
Yes if the replacement is incompatible, incorrectly wired or incorrectly configured for the heat pump and backup-heating system.
Can switching from Heat to Cool cause a delay?
Yes. Compressor protection can delay operation after mode changes.
Why does the heat pump wait after a power outage?
Many systems use an anti-short-cycle or restart delay to protect the compressor after power is restored.
Is a three-minute delay normal?
Some equipment uses approximately a three-minute compressor protection delay, while other equipment uses different timing. Check the manufacturer documentation for the installed model.
Can the outdoor unit be running even if I cannot hear it?
Yes. Variable-speed inverter systems can be very quiet at low output.
How can I tell whether the compressor is running?
Homeowners should avoid close mechanical or electrical inspection. Note normal sound, airflow and system performance, while professional diagnosis can confirm actual compressor operation.
Can the outdoor fan run while the compressor is off?
Control behaviour varies by system. The operating sequence should be compared with manufacturer information before assuming a fault.
Can the compressor run while the outdoor fan is off?
Yes during normal defrost on many heat pumps. Outside expected defrost operation, this condition may need prompt diagnosis.
Should I keep running it if the compressor is on but the fan is not?
Outside a known normal defrost sequence, shut the system off and arrange service.
Can a breaker trip stop only the outdoor unit?
Yes. Indoor and outdoor components can have separate electrical supplies.
Why is my thermostat still on after the outdoor breaker trips?
The thermostat or indoor equipment may receive power from a different circuit.
Should I reset a tripped heat pump breaker?
Do not repeatedly reset a breaker that continues to trip. A recurring trip requires professional electrical and HVAC diagnosis.
Can I replace the breaker with a larger one?
No. Overcurrent protection must match the equipment and electrical design.
Can I open the outdoor disconnect?
Do not open electrical equipment for troubleshooting unless you are appropriately qualified to perform the regulated work.
Can a fuse stop the outdoor heat pump?
Yes. Depending on system design, control or equipment protection fuses can affect operation.
Can I replace the heat pump fuse myself?
Do not open HVAC electrical compartments for diagnosis. A blown fuse can also be evidence of another fault that should be identified.
Can low voltage stop the outdoor unit?
Control-power or supply problems can prevent normal operation.
Can a loose wire cause intermittent outdoor operation?
Yes. Electrical or communication connections can create intermittent faults.
Can a communication error stop the outdoor unit?
Yes, particularly on ductless and communicating variable-capacity systems.
Why are all my mini-split heads showing an error?
A shared outdoor power, communication, control or refrigeration fault can affect all zones.
Why is only one mini-split head not working?
If other zones operate normally, a local indoor-unit, sensor, fan or communication problem may be more likely than total outdoor failure.
Can conflicting multi-zone modes stop a zone?
Yes. Some multi-zone systems cannot provide heating and cooling simultaneously to different connected indoor units.
Can an outdoor control board fail?
Yes. Outdoor boards can develop faults, but power, sensors, communication and other components should be checked before replacement.
Can an inverter board fail?
Yes. Inverter electronics are major components in variable-capacity equipment.
Is an inverter the same as a compressor?
No. The inverter controls electrical power supplied to the variable-speed compressor. Either component can develop a fault.
Does an inverter fault mean I need a new heat pump?
Not automatically. Compare repair cost, warranty, equipment age, parts availability and the condition of the compressor and refrigeration system.
Can a compressor fail without making noise?
Yes. Compressor faults can be electrical, mechanical or electronic and do not always produce dramatic sound.
Does silence mean the compressor is dead?
No.
Can compressor protection make it look dead?
Yes. The control system can intentionally prevent compressor operation when a protective condition exists.
Can a bad sensor stop the compressor?
Yes. Sensor information can be used for operating and protection decisions.
Can a refrigerant leak stop the outdoor unit?
It can contribute to abnormal refrigeration conditions that trigger protection, but an inactive outdoor unit does not prove a refrigerant leak.
Does low refrigerant always produce an error code?
No. Behaviour varies by system and the severity of the condition.
Should I add refrigerant to see whether it starts?
No. Refrigerant should only be adjusted after professional diagnosis using the correct equipment-specific procedure.
Can too much refrigerant stop a heat pump?
Incorrect charge can create abnormal operating conditions and reduce system performance. Professional testing is needed to determine actual charge condition.
Can a blocked coil trigger protection?
Yes. Restricted heat-exchanger airflow can create abnormal operating conditions.
Can outdoor fan failure stop the compressor?
Depending on system controls and resulting conditions, fan failure can lead to protection or shutdown.
Can a condensate float switch stop the outdoor unit?
On systems equipped and wired with condensate overflow protection, a drain safety can interrupt cooling operation or other control functions.
Why would a drain problem stop an outdoor heat pump?
Some systems intentionally interrupt operation when condensate backup is detected to reduce the risk of water damage.
Can a power surge damage the outdoor unit?
Electrical disturbances can affect control boards, inverter electronics, motors and compressors.
Should I shut the heat pump off if I smell burning?
Yes. Stop operation and arrange professional service.
Should I shut it off if I see smoke?
Yes.
Should I shut it off if the breaker repeatedly trips?
Yes. Do not continue resetting electrical protection.
Should I shut it off if the fan hits ice?
Yes. Continued operation can damage the fan, motor or coil.
Why is my central blower running but there is no heat?
The outdoor heat pump may be unavailable, the blower may be operating in Fan mode or the system may have another heating or control fault.
Why is my central blower running and the air is warm even though the outdoor unit is off?
Electric auxiliary heat or a dual-fuel furnace may be providing the heat.
Can this increase my electric bill?
Yes if a full-electric system relies heavily on electric resistance backup instead of normal heat-pump operation.
Can my furnace hide a heat pump problem?
In a dual-fuel system, the furnace can maintain comfort while an outdoor heat-pump problem remains unresolved.
Why is my outdoor unit off in mild weather but the furnace is running?
The system may have a heat-pump fault or an incorrect control configuration if this behaviour is unexpected for the installed design.
Can a newly installed heat pump fail to start because of setup?
Yes. Wiring, control configuration, equipment matching or commissioning can prevent normal operation.
Should a new outdoor unit be replaced immediately if it will not start?
No. Verify installation, controls, electrical supply, communication and manufacturer diagnostics first.
Can maintenance help prevent outdoor-unit failures?
Regular maintenance can identify airflow, coil, electrical, fan and operating problems before some become larger failures.
How often does NRCan recommend heat pump maintenance?
Natural Resources Canada currently recommends qualified professional maintenance annually.
How often should I check the filter?
Follow the equipment instructions. NRCan also currently advises regular filter cleaning or replacement, with guidance for many air-based systems around every three months.
Should I keep furniture away from indoor registers?
Yes. Blocked supply or return airflow can reduce system efficiency and contribute to poor operation.
Should vegetation be kept away from the outdoor unit?
Yes. Maintain the equipment manufacturer’s required airflow and service clearances.
Can I cover the outdoor unit in winter?
No while the heat pump is operating. It requires outdoor airflow for heating.
What should I tell the service technician?
Report the operating mode, setpoint, fault codes, whether indoor airflow works, whether backup heat is running, any breaker trip, icing, unusual sound, recent power outage and recent HVAC or electrical work.
Should I take a video of the problem?
A safe recording of sounds, fault codes or intermittent behaviour can be useful. Do not approach damaged or moving equipment to obtain it.
How does a technician know whether the compressor is bad?
Professional diagnosis evaluates operating demand, electrical supply, inverter or controls, compressor electrical condition and refrigeration-system behaviour as appropriate for the equipment.
Should the inverter be checked before replacing the compressor?
On inverter-driven equipment, the compressor and drive system need to be evaluated together rather than assuming either component from the symptom alone.
Does a dead outdoor unit always mean an expensive repair?
No. The cause can range from a control or wiring problem to a major inverter or compressor failure.
Does an outdoor-unit fault mean I need a new heat pump?
No. Many electrical, control, fan and sensor faults are serviceable.
When should replacement be considered?
Replacement deserves stronger consideration when major failures occur on older equipment with repeated repair history, coil problems, obsolete parts or poor original system design.
Can I replace only the outdoor unit?
Sometimes, but compatibility with the indoor equipment, controls, refrigerant and certified system match must be verified.
Can I keep the indoor air handler?
Possibly if it is compatible with the proposed replacement outdoor equipment and meets airflow and control requirements.
Can I keep my furnace?
Possibly in a suitable dual-fuel replacement design after compatibility and airflow are evaluated.
How much does Bernoulli charge to diagnose an existing heat pump?
The current diagnostic appointment charge is $135.
Does the $135 include the repair?
No. Repair labour, replacement parts, refrigerant and additional materials are separate from the diagnostic appointment.
Is a new heat pump replacement estimate free?
Yes. New heat pump installation and replacement estimates are currently free.