Updated July 27, 2026: Heat pump controls, refrigerant procedures, fault codes and cooling performance vary by manufacturer and model. Follow the operating instructions supplied with your equipment and leave electrical and refrigerant work to qualified professionals.
Heat pump not cooling? Start by checking the thermostat mode, temperature setting, fan setting, air filter, indoor airflow and outdoor-unit condition. A heat pump may run without cooling properly because of a simple control setting, but problems with dirty coils, low airflow, refrigerant, the reversing valve, sensors, fans, electrical components or the compressor can also reduce cooling.
The most important question is what the system is actually doing. Is it running but blowing warm air? Is the indoor fan operating while the outdoor unit remains off? Does it cool for a while and then stop? Is the indoor coil frozen? Is one floor comfortable while another stays hot? These symptoms point toward different causes.
Do not repeatedly reset breakers, add refrigerant without diagnosing the cause, continue running a system with a frozen indoor coil or open electrical equipment to troubleshoot it yourself.
This guide covers ducted, ductless, multi-zone, full-electric and dual-fuel heat pumps and answers the common cooling questions homeowners in British Columbia face during warm weather.
Why Is My Heat Pump Not Cooling?
A heat pump that does not cool may have a control problem, airflow problem, refrigeration problem, electrical fault or an issue with how the system was designed.
Common causes include:
- Thermostat not set to Cool
- Incorrect fan setting
- Dirty air filter
- Blocked or restricted ductwork
- Dirty indoor coil
- Dirty outdoor coil
- Frozen indoor coil
- Low refrigerant
- Refrigerant leak
- Refrigerant-flow restriction
- Reversing-valve problem
- Indoor or outdoor fan failure
- Electrical fault
- Sensor or control-board problem
- Compressor or inverter failure
- Duct leakage
- Insufficient cooling capacity
First Question: Is the Heat Pump Running?
If nothing is operating, start with thermostat settings, controls and power.
If the indoor blower runs but the outdoor unit does not, the problem is different.
If both units run but the air is not cooling, airflow, refrigeration performance, reversing-valve operation and actual system capacity become more important.
Start With the Symptom Before Guessing the Cause
| What You Notice | Possible Areas to Check |
|---|---|
| Nothing turns on | Thermostat, power, breaker, controls, communication |
| Indoor fan runs but outdoor unit is off | Thermostat, disconnect, breaker, controls, outdoor unit electrical fault |
| Both units run but air is warm | Mode, refrigerant, reversing valve, compressor, coils, airflow |
| Cooling works briefly then stops | Frozen coil, airflow, electrical protection, refrigerant, controls |
| Airflow is very weak | Filter, blower, indoor coil, ductwork, zoning |
| Ice appears on indoor coil or refrigerant pipe | Airflow, filter, blower, refrigerant, restriction |
| One floor stays hot | Duct balance, heat gain, return air, system design |
| One ductless head does not cool | Mode, filter, fan, sensor, refrigerant distribution, communication |
| System cools but humidity remains high | Sizing, fan speed, runtime, infiltration, controls |
| System runs constantly without reaching setpoint | Capacity, airflow, coils, refrigerant, duct leakage, building load |
Different symptoms can share causes, so professional diagnosis should use measurements rather than selecting a replacement part from the symptom alone.
What Should You Check Before Calling a Technician?
Start with checks that do not require opening equipment.
- Set the thermostat to Cool.
- Set the cooling temperature below the current indoor temperature.
- Check whether the fan is set to Auto, On or Circulate.
- Check schedules, Hold, Away and Vacation settings.
- Record any fault code.
- Check the central air filter.
- Clean ductless filters if visibly dirty.
- Open supply registers.
- Clear return-air grilles.
- Check that furniture or curtains are not blocking ductless units.
- Look at the outdoor unit without opening the cabinet.
- Remove loose leaves or vegetation blocking airflow.
- Check for ice on the indoor coil or refrigerant piping.
- Check whether water is leaking from indoor equipment.
Do Not Expect Instant Cooling
A heat pump may use a protective delay before restarting the compressor after being shut off or after a control change.
Give the equipment time to follow its normal startup sequence.
Keep Windows and Exterior Doors Closed
Open windows and doors add heat and humidity faster than the system may be able to remove them.
Cause 1: Thermostat Is Not Set to Cool
It sounds simple, but mode settings create a surprising number of cooling complaints.
Confirm the thermostat is set to Cool, not:
- Heat
- Fan Only
- Dry
- Off
- Auto when automatic changeover is unwanted
Why Auto Mode Can Cause Confusion
ENERGY STAR recommends selecting Heat or Cool rather than Auto when automatic changeover is unnecessary.
Auto mode can switch operating modes as indoor conditions move between programmed heating and cooling limits.
This may be especially confusing during spring and fall when outdoor conditions change quickly.
For general operating guidance, review the official ENERGY STAR air-source heat pump guidance.
Check the Cooling Setpoint
If the room is 24°C and the thermostat is also set to 24°C, the system may not have an active cooling demand.
Set the desired cooling temperature below the current room temperature and allow the normal startup sequence to begin.
Cause 2: Indoor Fan Is Running Without Active Cooling
A running blower does not prove the heat pump compressor is cooling.
Fan On
If the thermostat fan is set to On, the indoor blower may run continuously even when the compressor is off.
The air then feels like room-temperature air rather than conditioned air.
Fan Auto
For many systems, Auto allows the fan to follow cooling demand and equipment controls.
Circulate
Some controls periodically run the blower for air mixing even when there is no active compressor cooling.
Ventilation Integration
The blower may also run because it is integrated with:
- An HRV
- An ERV
- Whole-home ventilation
- Air filtration equipment
Check whether the outdoor unit is running before assuming that blower airflow represents active cooling.
Cause 3: Dirty or Restrictive Air Filter
A dirty filter reduces airflow across the indoor evaporator coil.
ENERGY STAR recommends checking HVAC filters regularly, especially during heavy heating and cooling use. A dirty filter makes the system work harder and can contribute to equipment problems. Review the ENERGY STAR maintenance checklist.
A Dirty Filter Can Cause:
- Weak airflow
- Reduced cooling capacity
- Long run times
- Indoor coil freezing
- Higher energy use
- Blower stress
Check Filter Direction
Central filters should be installed in the correct airflow direction.
A New Filter Can Still Cause Trouble
A new filter with excessive pressure drop may reduce airflow even though it is completely clean.
Filter selection should consider:
- Filter dimensions
- Filter depth
- Return duct size
- Blower capability
- Manufacturer airflow requirements
Cause 4: Low Indoor Airflow
The filter is only one part of the airflow path.
Central Ducted Problems Include:
- Blocked return grilles
- Closed supply registers
- Closed balancing dampers
- Crushed flexible duct
- Undersized return ductwork
- Dirty evaporator coil
- Dirty blower wheel
- Incorrect blower speed
- Failed blower motor
- Improper zoning
Ductless Airflow Problems Include:
- Dirty mesh filters
- Dirty indoor coil
- Dirty blower wheel
- Blocked air intake
- Curtains blocking discharge
- Furniture directly beneath the indoor unit
- Indoor fan failure
Why Low Airflow Reduces Cooling
The indoor coil needs enough warm room air passing across it to absorb heat.
When airflow falls too low, cooling capacity decreases and the coil may become cold enough for moisture on its surface to freeze.
What a Technician Can Measure
A ducted airflow diagnosis may include:
- Total external static pressure
- Filter pressure drop
- Coil pressure drop
- Blower speed
- Supply temperature
- Return temperature
- Delivered airflow
ENERGY STAR notes that airflow problems reduce HVAC efficiency and cooling performance.
Cause 5: Outdoor Airflow Is Restricted
During cooling mode, the heat pump moves heat from inside the home to the outdoor coil.
The outdoor unit must then release that heat to outside air.
Restrictions May Include:
- Leaves
- Grass clippings
- Vegetation
- Tree seeds
- Lint
- Plastic debris
- Fence panels
- Stored items
- Construction dust
Outdoor Placement Can Also Matter
Performance may suffer when the outdoor unit is:
- Inside a tight enclosure
- Too close to a wall
- Blocked by vegetation
- Discharging directly toward another outdoor unit
- Recirculating its own hot discharge air
Safe Homeowner Action
Remove loose debris from around the equipment and maintain manufacturer clearances.
Do not insert tools through the fan guard or open the electrical compartment.
Cause 6: Dirty Indoor or Outdoor Coil
Both heat exchangers need clean surfaces and proper airflow.
ENERGY STAR specifically includes cleaning evaporator and condenser coils as part of cooling-system maintenance because dirty coils reduce cooling ability and make the system operate longer.
Dirty Indoor Coil Symptoms
- Weak airflow
- Reduced cooling
- Frozen coil
- Long run time
- Musty odour
- Water problems
Dirty Outdoor Coil Symptoms
- Reduced cooling capacity
- Long compressor run time
- High operating pressure
- Fault codes
- High compressor load
Should a Homeowner Wash the Coil?
Loose surrounding debris can be removed safely.
Professional coil cleaning may require:
- Electrical isolation
- Cabinet disassembly
- Protecting electrical controls
- Cleaning from the correct direction
- Using methods compatible with the coil
Do not use a pressure washer. Coil fins are thin and easily damaged.
Cause 7: The Indoor Coil Is Frozen
An evaporator coil covered in ice cannot cool the home correctly because airflow through the coil becomes increasingly restricted.
Signs of a Frozen Coil
- Weak airflow
- Cooling gradually disappears
- Ice on the larger insulated refrigerant line
- Water appears after the system shuts off
- Indoor fan runs but rooms remain hot
- Outdoor unit runs for long periods
Common Causes
- Dirty filter
- Low airflow
- Dirty indoor coil
- Blower failure
- Low refrigerant
- Refrigerant restriction
- Control or sensor problem
What Should You Do?
Turn cooling off so additional ice does not form.
If the manufacturer permits it and there is no water or electrical safety concern, indoor fan operation may help move room air across the coil while it thaws.
Check the filter and visible airflow restrictions.
Do not restart cooling until the coil has thawed.
If It Freezes Again
Repeated icing requires diagnosis.
Do not continue a cycle of thawing, restarting and hoping the refrigeration system develops a sense of responsibility.
Cause 8: Low Refrigerant or a Refrigerant Leak
A low refrigerant charge can reduce cooling capacity and contribute to indoor coil icing.
Possible Symptoms
- Weak cooling
- Long run time
- Frozen indoor coil
- Ice on refrigerant piping
- Fault codes
- Abnormal pipe temperatures
- Oil residue near refrigerant connections
Does a Heat Pump Use Up Refrigerant?
No. Refrigerant circulates inside a sealed system and is not normally consumed.
Low refrigerant may indicate:
- A leaking connection
- Indoor coil leak
- Outdoor coil leak
- Damaged refrigerant piping
- Incorrect initial charge
- A previous incomplete repair
Adding Refrigerant Is Not the First Diagnostic Step
Weak cooling can also result from low airflow or dirty coils.
A technician should confirm operating conditions before changing the refrigerant charge.
When a Leak Is Confirmed
The repair process may include:
- Locating the leak
- Determining whether repair is practical
- Recovering refrigerant where required
- Repairing or replacing the affected component
- Pressure testing
- Evacuating the system
- Charging according to manufacturer requirements
- Testing cooling performance
Cause 9: Refrigerant Flow Is Restricted
The refrigerant system needs controlled flow between the high-pressure and low-pressure sides of the system.
Possible restriction points include:
- Electronic expansion valve
- Thermostatic expansion valve
- Filter-drier
- Kinked refrigerant line
- Contamination inside the system
Possible Symptoms
- Poor cooling
- Coil icing
- Unusual refrigerant temperatures
- Abnormal operating pressures
- Fault codes
- Compressor stress
These symptoms can overlap with low refrigerant and airflow problems.
Diagnosis requires pressure, temperature and equipment-data analysis.
Cause 10: Reversing Valve Is Not Switching Into Cooling
A heat pump provides both heating and cooling by changing refrigerant direction.
The reversing valve is central to that process.
Possible Symptoms of a Reversing-Valve Problem
- Heat pump heats normally but does not cool
- System remains in heating operation despite a cooling call
- Air from registers feels warm in Cool mode
- Valve changes mode inconsistently
- Fault codes or abnormal pressures occur
The Valve Is Not Always the Problem
The issue may instead involve:
- Thermostat command
- Control-board output
- Valve solenoid coil
- Control wiring
- Refrigerant pressure conditions
- Mechanical valve failure
A technician should verify the control signal and refrigeration response before condemning the valve.
Cause 11: Outdoor Fan Is Not Working Correctly
The outdoor fan moves air through the condenser coil during cooling.
If it fails, the heat pump may be unable to release indoor heat effectively.
Possible Causes
- Fan motor failure
- Control-board problem
- Electrical connection failure
- Damaged blade
- Debris blocking the fan
- Motor-control problem
Possible Symptoms
- Compressor operates but outdoor fan does not
- Outdoor unit becomes unusually hot
- Cooling stops
- System trips a protective fault
- Breaker or electrical protection operates
Turn the system off if the fan is striking the cabinet or another object.
Do not reach through the fan guard even when the fan appears stopped.
Cause 12: Indoor Blower Problem
The heat pump can create a cold indoor coil but still fail to cool the home if the blower cannot move enough air.
Possible Blower Problems
- Failed motor
- Dirty blower wheel
- Incorrect speed setting
- Control-board problem
- High static pressure
- Loose electrical connection
Common Symptoms
- Very little airflow
- Indoor coil freezing
- Air handler makes unusual noise
- Some registers have almost no airflow
- Cooling shuts down on a fault
Why a Dirty Blower Wheel Matters
Dust buildup changes the shape of the fan blades and reduces the amount of air the blower can move.
This issue is particularly relevant to ductless indoor units where blower-wheel contamination may exist behind apparently clean filters.
Cause 13: Electrical or Power Problem
A heat pump has electrical components in the indoor and outdoor equipment, and some systems use separate circuits.
Possible Problems
- Tripped breaker
- Open disconnect
- Failed contactor or relay
- Loose terminal
- Failed control transformer
- Voltage problem
- Damaged wiring
- Failed circuit board
- Communication fault
Indoor Fan Works but Outdoor Unit Does Not
This symptom may indicate that:
- The outdoor unit has lost power
- A control signal is missing
- The outdoor equipment has entered protection
- A board or motor has failed
Do Not Repeatedly Reset a Breaker
A breaker is a protective device.
If it trips again after being reset, stop and request diagnosis.
ENERGY STAR includes electrical connection, motor voltage and current checks in routine professional HVAC maintenance because electrical problems can reduce safe operation and equipment life.
Cause 14: Sensor, Thermostat or Control-Board Fault
Modern heat pumps use sensors throughout the refrigeration and air-distribution system.
Sensors May Monitor:
- Indoor air temperature
- Outdoor air temperature
- Indoor coil temperature
- Outdoor coil temperature
- Refrigerant pipe temperature
- Compressor temperature
- Pressure
A Sensor or Control Problem May Cause:
- Compressor not starting
- Cooling stopping early
- Incorrect fan speed
- Wrong refrigerant-valve position
- Fault codes
- Unexpected system shutdown
Save the Fault Code
Write down or photograph error codes before turning power off.
A fault code is diagnostic information, not an annoying message that needs to be erased before the technician arrives.
Cause 15: Compressor or Inverter Problem
The compressor creates the refrigerant pressure difference needed to move heat out of the home.
Possible Symptoms
- Indoor blower operates but no cooling occurs
- Outdoor fan runs but compressor does not
- Compressor starts and quickly stops
- Breaker trips
- Fault code appears
- Outdoor unit makes severe mechanical noise
- Cooling disappears under high load
Variable-Speed Systems
Inverter heat pumps use electronic controls to vary compressor speed.
A problem may involve:
- Compressor
- Inverter module
- Power supply
- Temperature sensor
- Pressure condition
- Communication
Do Not Assume Compressor Failure
Several less expensive faults can prevent compressor operation.
Electrical and refrigeration tests should confirm the failure before a major component is replaced.
Cause 16: Ductwork Is Losing or Misdistributing the Cooling
A heat pump can cool correctly at the indoor coil while the home remains uncomfortable because the conditioned air does not reach the rooms properly.
Possible Problems
- Disconnected duct
- Leaking supply duct
- Crushed flexible duct
- Poorly insulated attic duct
- Closed balancing damper
- Undersized branch duct
- Insufficient return air
- Poor system balancing
Signs of a Distribution Problem
- One floor cools while another stays hot
- Airflow is strong near the equipment but weak farther away
- Some rooms become too cold while others never reach temperature
- The attic or crawl space feels unusually cool
- Return grilles are noisy
Replacing a heat pump will not repair a disconnected duct.
Cause 17: The Heat Pump Does Not Have Enough Capacity for the Cooling Load
A heat pump may be operating correctly but still struggle when the building cooling load is greater than the available equipment capacity.
Cooling Load Is Affected By:
- Outdoor temperature
- Sun exposure
- Window area and orientation
- Insulation
- Air leakage
- Ceiling height
- Number of occupants
- Cooking and appliances
- Upper-floor heat gain
Possible Signs of Insufficient Capacity
- System runs continuously
- Indoor temperature slowly rises during peak afternoon heat
- Cooling improves after sunset
- Airflow and refrigeration measurements are otherwise normal
Do Not Automatically Install a Bigger Unit
Oversizing can create another set of problems, including short cycling and weaker humidity control.
The proper approach is a cooling and heating load calculation followed by equipment selection that matches both loads and the equipment capacity range.
Why Is My Heat Pump Running but Not Cooling?
This complaint narrows the problem considerably.
If both indoor and outdoor equipment appear to run, possible causes include:
- Wrong thermostat mode
- Low indoor airflow
- Dirty coils
- Frozen evaporator coil
- Low refrigerant
- Refrigerant restriction
- Reversing-valve problem
- Compressor not producing normal capacity
- System undersized for the current load
Check the Airflow First
Strong room-temperature airflow and weak airflow point toward different diagnostic paths.
Strong Airflow but No Cooling
Refrigeration performance, mode selection and compressor operation become more important.
Very Weak Airflow
Check filter, coil, blower and duct restrictions.
Why Is the Indoor Fan Running but the Outdoor Heat Pump Is Not?
The indoor blower can operate independently of the outdoor compressor unit.
Possible Causes Include:
- Fan set to On
- No active cooling call
- Outdoor-unit breaker or disconnect
- Control delay
- Fault lockout
- Communication problem
- Outdoor control-board failure
- Compressor or inverter problem
Check the Thermostat First
Confirm Cool mode and a cooling setpoint below room temperature.
Do Not Open the Outdoor Electrical Panel
The outdoor unit contains line-voltage electrical equipment and stored electrical energy in some components.
Professional testing is appropriate when the unit does not respond to a confirmed cooling demand.
Why Is My Upstairs Hot Even Though the Heat Pump Is Cooling?
This is a common comfort complaint in multi-level homes.
Upper Floors Often Have Higher Cooling Loads
Contributing factors include:
- Roof heat gain
- Attic insulation
- West-facing windows
- Large glazing areas
- Air leakage
- Long duct runs
- Limited return air
Possible HVAC Problems
- Insufficient upstairs branch airflow
- Dampers not balanced for summer
- Duct leakage in attic
- Return air concentrated on lower level
- Thermostat located downstairs
- System capacity insufficient for peak cooling load
Do Not Solve It by Closing Most Downstairs Registers
Closing many registers can raise system static pressure and reduce total airflow.
Better solutions may include:
- Air balancing
- Duct modifications
- Improved return air
- Attic air sealing and insulation
- Zoning where properly designed
- A dedicated ductless zone
Ductless Heat Pump Not Cooling
Ductless systems have several additional items to check.
Confirm Cool Mode
Use the cooling mode shown in the manufacturer instructions.
Do not confuse:
- Cool
- Dry
- Fan
- Auto
Check the Filters
Ductless filters should be cleaned when visibly dirty or according to the filter indicator and manufacturer instructions. ENERGY STAR specifically recommends keeping heat pump filters clean.
Check the Indoor Blower Wheel
A ductless unit can have clean filters but a heavily contaminated blower wheel.
Signs include:
- Weak airflow
- Uneven air discharge
- Dirt on louvers
- Musty smell
- Higher fan noise
Check Unit Location
Furniture, shelving or curtains should not interfere with air intake or discharge.
One Indoor Head Cannot Cool Every Closed Room
A unit in an open living room may cool that zone effectively while closed bedrooms remain warm.
This is often a distribution issue rather than a refrigeration failure.
Why Is One Multi-Zone Indoor Unit Not Cooling?
A multi-zone system connects several indoor units to one outdoor unit.
If one zone has a problem while the others cool normally, investigate the affected zone before assuming the entire outdoor system has failed.
Possible Causes Include:
- Mode conflict
- Dirty filter
- Indoor fan problem
- Sensor fault
- Electronic expansion valve problem
- Control or communication fault
- Refrigerant-distribution problem
Check Operating Modes Across All Zones
Many multi-zone systems require connected indoor units to operate in compatible modes.
One unit requesting heating while others request cooling may prevent expected operation depending on the system design.
All Zones Calling at Once
The outdoor unit shares its available capacity among active indoor units.
If every zone has a strong cooling demand, individual indoor units may not receive their full nameplate capacity simultaneously.
Why Is the Heat Pump Cooling but the House Still Feels Humid?
Cooling comfort depends on temperature and humidity.
A room can reach the thermostat setpoint and still feel uncomfortable when moisture removal is limited.
Possible Causes Include:
- Oversized heat pump
- Short cooling cycles
- Indoor fan speed too high
- Fan running continuously after compressor shutdown
- High outdoor-air infiltration
- Open windows or doors
- High indoor moisture generation
- Drainage or coil problems
Why Oversizing Can Affect Humidity
An oversized system may reduce air temperature quickly and shut off before operating long enough to remove as much moisture as a better-matched system.
Fan Operation Matters
Continuous fan circulation after a cooling cycle may affect humidity behaviour in some systems because moisture remaining on the coil can re-enter the airstream.
Control settings should match the equipment design.
Check the Condensate Drain
ENERGY STAR recommends inspecting the condensate drain in a heat pump operating in cooling mode because a blocked drain can cause water damage and affect indoor humidity.
Why Is My New Heat Pump Not Cooling Properly?
A newly installed system should not automatically be assumed defective.
Installation and commissioning should be reviewed first.
Possible Installation Causes
- Incorrect equipment sizing
- Incorrect refrigerant charge
- Refrigerant leak
- Airflow not set correctly
- Restricted existing ductwork
- Incorrect thermostat configuration
- Reversing-valve control problem
- Improper matched equipment combination
- Indoor-unit placement problem
- Ductless zone sizing problem
A New System Should Be Commissioned
Commissioning may include:
- Confirming model combinations
- Checking control configuration
- Verifying airflow
- Measuring static pressure
- Checking refrigerant performance
- Testing condensate drainage
- Testing heating and cooling modes
- Checking electrical operation
ENERGY STAR recommends correct airflow, refrigerant charge and equipment setup as essential parts of quality HVAC installation.
Why Is My Heat Pump Running Constantly but the House Is Not Getting Cooler?
Long cooling cycles can be normal during very hot weather, especially with variable-capacity equipment.
Continuous operation becomes more concerning when indoor temperature continues rising.
Possible Causes Include:
- High outdoor temperature and solar load
- Dirty filter
- Low airflow
- Dirty coils
- Refrigerant problem
- Duct leakage
- Equipment undersizing
- Building envelope problems
Check the Time of Day
A system that holds temperature overnight but loses ground every sunny afternoon may be dealing with high peak cooling load.
Check Windows and Solar Gain
West- and south-facing glazing can significantly increase afternoon cooling demand.
Window coverings and exterior shading can reduce part of that load without changing the HVAC equipment.
What Should You Not Do When a Heat Pump Stops Cooling?
Do Not Set the Thermostat Extremely Low
Setting the thermostat to 15°C does not make the heat pump produce colder air than a normal cooling call.
It only creates a longer demand.
Do Not Keep Running a Frozen Coil
Continuing to operate cooling can increase ice accumulation and may increase compressor stress.
Do Not Add Refrigerant Without Leak Diagnosis
Refrigerant is not a consumable maintenance fluid.
Do Not Repeatedly Reset a Breaker
Repeated trips indicate a problem that needs electrical diagnosis.
Do Not Close Most Supply Registers
This can increase static pressure and reduce total airflow.
Do Not Pressure-Wash Coils
High-pressure water can damage fins and electrical components.
Do Not Open Refrigerant or Electrical Components
Homeowner troubleshooting should remain limited to safe external checks.
When Should You Turn a Non-Cooling Heat Pump Off?
Loss of cooling is uncomfortable, but it is not always an emergency.
Turn Cooling Off When:
- The indoor coil or refrigerant pipe is heavily iced
- The breaker repeatedly trips
- There is a burning or electrical smell
- The compressor makes severe grinding or impact sounds
- Water is reaching electrical equipment
- The outdoor fan is striking the cabinet
- Visible electrical wiring is damaged
What If the Indoor Coil Is Frozen?
Stop compressor cooling and allow the ice to thaw safely.
Be prepared for condensate water as the ice melts.
Protect the surrounding building materials and request diagnosis if the coil freezes again.
What If There Is Only Weak Cooling?
Check filters, registers, thermostat settings and outdoor-unit clearance.
If cooling remains weak, professional testing is appropriate.
What Should a Technician Check When a Heat Pump Is Not Cooling?
A good diagnosis should establish whether the problem is control, airflow, refrigeration, electrical, distribution or capacity related.
The technician may inspect:
- Thermostat mode and cooling demand
- Thermostat temperature accuracy
- Fault-code history
- Indoor and outdoor communication
- Filter condition
- Indoor coil condition
- Outdoor coil condition
- Indoor blower operation
- Outdoor fan operation
- Supply and return temperatures
- Temperature difference across the indoor system
- Total external static pressure
- Delivered airflow
- Compressor operation
- Inverter operating data where available
- Refrigerant pressures
- Refrigerant pipe temperatures
- Superheat or subcooling where applicable
- Electronic or thermostatic expansion-device operation
- Evidence of refrigerant leaks
- Reversing-valve operation
- Voltage and electrical current
- Control-board and sensor operation
- Condensate drainage
- Duct leakage and room distribution
- System capacity compared with building cooling load
Temperature Difference Alone Is Not a Complete Diagnosis
A supply-to-return temperature difference can provide useful information, but it should be interpreted with:
- Airflow
- Indoor humidity
- Outdoor conditions
- Equipment stage
- Manufacturer specifications
A single temperature reading should not be used to decide that refrigerant is low.
Refrigerant Should Be Diagnosed From Measurements
ENERGY STAR includes checking refrigerant condition and blower airflow as part of professional cooling maintenance because both affect cooling efficiency and performance.
Should You Repair or Replace a Heat Pump That Is Not Cooling?
Most cooling problems do not automatically require replacement.
Repair May Make Sense When:
- The thermostat or sensor has failed
- A filter or coil is restricted
- The blower or fan needs repair
- A control component has failed
- A repairable refrigerant leak is found
- The reversing valve or its control can be repaired
- The system is relatively young
System Modification May Be Better Than Equipment Replacement When:
- Return airflow is inadequate
- Duct balancing is poor
- One floor has insufficient supply airflow
- Duct leakage is significant
- Indoor-unit placement is poor
- Zoning needs redesign
Replacement May Be More Practical When:
- The compressor has failed on an older system
- Coils have recurring refrigerant leaks
- Major parts are no longer available
- The equipment needs repeated expensive repairs
- The system is significantly undersized or oversized
- Several major components are deteriorating
- A previous installation has fundamental compatibility problems
Do Not Replace the Unit Before Understanding Why It Failed
If poor airflow, incorrect sizing or installation problems caused the old system to struggle, installing similar equipment without correcting those conditions can reproduce the same problem.
Heat Pump Cooling Diagnosis in Metro Vancouver and Fraser Valley
Bernoulli Heating and Cooling provides heat pump diagnostic and repair service across Metro Vancouver and the Fraser Valley.
We diagnose ducted, ductless, multi-zone, full-electric and dual-fuel heat pump systems with cooling problems including weak airflow, frozen coils, refrigerant leaks, control faults, fan problems, electrical failures and uneven room temperatures.
The current diagnostic appointment charge for an existing heat pump is $135. Repair labour, refrigerant, replacement components and additional materials are quoted separately when required.
New heat pump installation estimates are free.
Call 604-518-4438 or email heatingbernoulli@gmail.com to arrange service.
Explore local heat pump installation information:
For general homeowner guidance, review the official ENERGY STAR maintenance checklist and Natural Resources Canada heat pump guide.
Heat Pump Not Cooling: Frequently Asked Questions
Why is my heat pump running but not cooling?
Possible causes include incorrect thermostat mode, low airflow, dirty coils, a frozen indoor coil, refrigerant problems, a reversing-valve fault or compressor problems.
Why is the heat pump blowing warm air in Cool mode?
Check thermostat mode first. If Cool is selected and the system continues delivering warm air, refrigeration performance, reversing-valve operation and compressor operation should be evaluated.
Why does my heat pump cool for a few minutes and then stop?
Possible causes include indoor coil icing, low airflow, electrical protection, control faults, sensors or refrigeration problems.
How long should a heat pump take to cool a house?
There is no fixed time. Recovery depends on indoor and outdoor temperatures, house size, solar gain, insulation, equipment capacity, airflow and the amount of temperature change requested.
Should I set the thermostat much lower to cool faster?
No. Setting an unusually low target creates a longer cooling demand but does not normally make the heat pump deliver colder air than its normal cooling operation.
What thermostat mode should I use?
Use Cool during the cooling season unless automatic changeover is specifically needed for the home.
Should the thermostat fan be on Auto?
Auto is suitable for many systems because fan operation follows cooling demand. Some systems intentionally use circulation or ventilation settings, so follow the installed control strategy.
Why is the indoor fan running but the outdoor unit is not?
The fan may be set to On or Circulate, or the outdoor equipment may have a power, control, communication, compressor or protection problem.
Can a dirty filter stop a heat pump from cooling?
Yes. Restricted airflow reduces cooling capacity and can cause the indoor coil to freeze.
Can closed vents cause poor cooling?
Closing many registers can increase duct pressure and reduce total airflow. It can also make room temperatures less balanced.
Why is there ice on my heat pump in summer?
Ice on the indoor coil or suction piping during cooling may result from low airflow, dirty filters, blower problems, low refrigerant or refrigerant restrictions.
Should I keep running the heat pump if the indoor coil is frozen?
No. Stop cooling so the ice can thaw. Check basic airflow issues and arrange diagnosis if freezing returns.
How long does a frozen coil take to thaw?
There is no fixed time. Ice thickness, airflow and indoor conditions affect thawing. Do not restart cooling while ice remains on the coil.
Why does water leak after my heat pump freezes?
A large amount of water may be produced as the ice melts. A blocked drain, damaged drain pan or condensate-pump problem can also contribute to leakage.
Can low refrigerant cause weak cooling?
Yes. Low refrigerant can reduce capacity and contribute to coil icing.
Does my heat pump need refrigerant every summer?
No. Refrigerant is not normally consumed. Repeated refrigerant additions indicate an unresolved leak or charging problem.
Can I tell if refrigerant is low by touching the pipes?
No. Pipe temperature alone cannot reliably diagnose refrigerant charge. Airflow, pressures, temperatures and equipment specifications should be evaluated together.
Why does my heat pump heat normally but not cool?
A problem may involve thermostat controls, the reversing valve, refrigeration controls, sensors or equipment operation specific to cooling mode.
Can a reversing valve cause no cooling?
Yes. A reversing valve or its control can prevent the system from switching correctly into cooling operation.
Why is my outside fan not spinning?
The fan motor, controls, wiring or outdoor unit power may have a problem. The system may also be in a control state where the fan is intentionally stopped. Professional diagnosis is appropriate if cooling is demanded and the outdoor system does not operate normally.
Why is the outdoor unit running but the house is still hot?
Possible causes include low airflow, dirty coils, refrigerant problems, compressor capacity issues, duct leakage or a cooling load greater than the system can handle.
Why is my upstairs hotter than downstairs?
Upper floors often have higher roof and solar heat gain. Duct balance, return-air design, attic conditions and thermostat location can also contribute.
Should I close downstairs vents to make upstairs cooler?
Avoid closing large numbers of registers. This can raise static pressure and reduce total system airflow. Proper balancing or duct modifications are safer approaches.
Why does one room stay hot while the rest of the house is cool?
The problem may involve branch airflow, a closed damper, duct leakage, inadequate return air, window heat gain or insulation rather than the heat pump itself.
Why is my ductless heat pump not cooling?
Check Cool mode, filters, fan operation, airflow obstructions and fault codes. Refrigerant, sensors, indoor fan or outdoor equipment may require professional diagnosis if the problem continues.
Why is only one mini-split head not cooling?
Possible causes include filter restriction, fan problems, sensors, controls, refrigerant distribution or communication affecting that indoor unit.
Can different mini-split heads be set to heating and cooling at the same time?
Many conventional multi-zone systems require connected indoor units to operate in compatible modes. Exact capability depends on the equipment design.
Why does my heat pump run constantly in summer?
Long operation may be normal during hot weather or with variable-capacity equipment. It needs evaluation when the indoor temperature continues rising or other abnormal symptoms are present.
Does running all day mean the heat pump is undersized?
Not necessarily. A variable system may run continuously at reduced output. Undersizing is more likely when the system operates near maximum capacity and cannot maintain temperature.
Why does the house feel humid even though it is cool?
Possible causes include equipment oversizing, short cycles, high fan speed, infiltration, continuous fan operation or high indoor moisture generation.
Can an oversized heat pump cool poorly?
It may cool the air quickly but cycle off before providing good humidity removal. Oversizing can also create comfort and airflow problems.
Can a heat pump be too small for cooling?
Yes. A system with insufficient capacity may run continuously and lose ground during peak outdoor heat or high solar gain.
Why did my new heat pump stop cooling properly right after installation?
Equipment sizing, refrigerant charge, airflow, thermostat configuration, controls, ductwork and commissioning should be reviewed.
Does a heat pump need annual maintenance for cooling?
Regular maintenance can identify filter, coil, drainage, electrical, airflow and refrigeration problems before peak cooling demand. ENERGY STAR recommends annual pre-season HVAC check-ups.
Why does my heat pump smell musty when cooling?
Moisture and contamination may be present on the indoor coil, blower wheel, drain pan or condensate system. Filter cleaning alone may not remove internal contamination.
Why is water dripping from my indoor ductless unit?
Possible causes include a blocked condensate line, incorrect drain slope, failed condensate pump, dirty coil or frozen indoor coil.
Should I turn off the heat pump if water is leaking?
Turn it off if water may contact electrical components or cause building damage. The drainage problem should be inspected.
Can a power outage cause my heat pump to stop cooling?
Yes. Controls may need to complete a restart sequence after power returns, and a surge or electrical fault may also affect equipment. Follow manufacturer restart instructions.
Why does the breaker trip when cooling starts?
Possible causes include compressor, fan motor, wiring, electrical-component or circuit problems. Do not repeatedly reset the breaker.
Can I repair a non-cooling heat pump myself?
Homeowners can check settings, filters, registers and visible outdoor obstructions. Refrigerant, electrical, compressor, control and internal equipment repairs should be completed professionally.
How does a technician know whether the problem is airflow or refrigerant?
The technician compares airflow, static pressure, supply and return temperatures, refrigerant pressures, pipe temperatures and manufacturer performance data.
Does poor cooling mean I need a new heat pump?
No. Filters, airflow, fans, controls, drainage and many refrigerant problems can be repaired. Replacement is more relevant when the equipment is aging, repeatedly failing, significantly mis-sized or has major compressor or coil damage.
How much is a Bernoulli heat pump diagnostic appointment?
Bernoulli Heating and Cooling currently charges $135 for a diagnostic appointment on an existing heat pump system. Repair labour, refrigerant, parts and additional materials are separate.