Updated August 12, 2026: Heat pump diagnostic procedures vary by manufacturer, model, system type, refrigerant, fault condition and available service tools. Not every service call requires every test in this guide. A qualified technician should select tests based on the complaint, equipment data and observed operating conditions.
A heat pump service call should begin with the symptom and progress toward measurable evidence. A technician may review thermostat settings and stored fault codes, inspect filters and coils, measure airflow and static pressure, test electrical supply and motor current, compare temperature sensors, evaluate compressor and fan operation, inspect condensate drainage and assess refrigerant-system performance when indicated.
A fault code can narrow the search, but it does not always identify the failed part. Likewise, one pressure, temperature or electrical reading rarely diagnoses a heat pump by itself. Good troubleshooting compares several measurements with manufacturer specifications and the conditions under which the system is operating.
Homeowners can help considerably by recording when the problem occurs, photographing error codes and describing whether the issue affects heating, cooling, defrost, one zone or the complete system.
What Happens During a Heat Pump Service Call?
A proper diagnostic visit usually follows a sequence rather than beginning with parts replacement.
- Listen to the homeowner’s description.
- Identify the equipment and system configuration.
- Review thermostat settings and error history.
- Visually inspect the system.
- Perform symptom-specific measurements.
- Compare readings with manufacturer requirements.
- Identify the likely cause.
- Explain the recommended repair or next diagnostic step.
- After repair, retest the system.
Not Every Test Is Needed on Every Call
For example:
- A condensate overflow may not require full refrigerant testing.
- A repeated breaker trip requires electrical diagnosis before routine performance testing.
- A weak-airflow complaint should not begin by adding refrigerant.
- A communication error may require control and wiring diagnosis before pressure readings.
Diagnosis Should Follow Evidence
A technician should be able to explain why a particular measurement or test is relevant to the symptom.
Heat Pump Diagnosis vs Maintenance vs Commissioning
| Service Type | Purpose | Typical Timing |
|---|---|---|
| Diagnostic service call | Find the cause of an existing symptom or fault | When the system is not operating normally |
| Preventive maintenance | Inspect, clean and verify operation before failure develops | Routine scheduled service |
| Commissioning | Verify a newly installed or significantly modified system performs according to design and manufacturer requirements | After installation or major alteration |
| Repair verification | Confirm that the diagnosed problem has actually been corrected | Immediately after repair |
A Maintenance Checklist Is Not Automatically a Diagnostic Procedure
A technician troubleshooting a specific failure may need tests beyond routine maintenance.
Commissioning Data Can Help Future Diagnosis
Original measurements such as:
- Airflow
- Static pressure
- Electrical readings
- Refrigerant commissioning data
- Thermostat configuration
provide a useful baseline when system performance later changes.
What Should Homeowners Record Before the Technician Arrives?
Record the Symptom
Examples:
- No heating
- No cooling
- Weak airflow
- Short cycling
- Outdoor unit freezing
- Water leakage
- Breaker trip
- Unusual noise
- High electricity use
Photograph Error Codes
Save:
- Thermostat display
- Ductless indoor-unit lights
- Manufacturer app notification
Record When the Problem Happens
For example:
- Only during heating
- Only during cooling
- Only during defrost
- Only below a certain outdoor temperature
- Only after several hours
- Only when multiple zones operate
Do Not Reset Repeatedly Before the Visit
Repeated power cycling can erase useful evidence or temporarily hide an intermittent fault.
1. Confirm the Homeowner’s Complaint
The first diagnostic tool is not a gauge or multimeter. It is a precise description of what changed.
Useful Questions Include:
- When did the problem begin?
- Was it sudden or gradual?
- Does it affect heating, cooling or both?
- Does the thermostat reach setpoint?
- Has the breaker tripped?
- Has any work recently been completed?
- Was there a power outage?
- Has the filter recently been changed?
Compare Current Behaviour With Normal Behaviour
Many heat pumps:
- Run for long periods normally
- Produce moderate supply-air temperatures
- Defrost periodically in winter
- Change fan and compressor speed continuously
Those behaviours should not be mistaken automatically for faults.
2. Identify the Equipment and System Configuration
Correct diagnosis begins with the exact equipment.
Record:
- Outdoor model number
- Indoor model number
- Serial numbers
- Thermostat or controller
- Refrigerant type
- Number of indoor zones
- Backup heating type
Determine the System Type
Possible configurations include:
- Central ducted heat pump
- Single-zone ductless
- Multi-zone ductless
- Full-electric heat pump with resistance backup
- Dual-fuel heat pump with gas furnace
Why Model Numbers Matter
Service procedures, fault codes, refrigerant charge methods and control logic are equipment-specific.
3. Review Thermostat and Controller Settings
A surprising number of apparent equipment problems begin at the control.
Check:
- Heat or Cool mode
- Setpoint
- Fan setting
- Emergency Heat status
- Schedule
- Outdoor-temperature lockouts
- Zone calls
- Installer configuration where appropriate
Communicating Systems Need Special Attention
The thermostat can control:
- Compressor capacity
- Blower airflow
- Backup heat stages
- Balance points
- Dehumidification
A Thermostat Can Be Operational but Misconfigured
Incorrect settings can mimic:
- Heat-pump failure
- AUX Heat problems
- Short cycling
- Insufficient capacity
4. Retrieve Active and Stored Heat Pump Fault Codes
Modern equipment can retain diagnostic history beyond what the homeowner sees.
Stored Information May Include:
- Active error
- Previous errors
- Lockout events
- Sensor faults
- Communication problems
- Compressor protection events
Manufacturer Service Tools Can Provide More Data
Some systems allow technicians to view real-time information such as:
- Compressor speed
- Fan speed
- Sensor temperatures
- Valve positions
- Current
- Operating mode
A Code Is a Starting Point
For example, a pressure-related protection code could result from:
- Airflow restriction
- Fan failure
- Refrigerant condition
- Sensor fault
Do Not Replace the Component Named in the Code Without Testing
The circuit surrounding that component must also be evaluated.
5. Inspect Filters, Registers and Obvious Airflow Restrictions
Airflow should be checked before drawing conclusions from many refrigeration measurements.
Inspect:
- Filter condition
- Correct filter size
- Filter airflow direction
- Return grilles
- Supply registers
- Visible duct restrictions
- Ductless filters
Why This Test Comes Early
Low airflow can affect:
- Coil temperatures
- Refrigerant pressures
- Heating output
- Cooling output
- Dehumidification
- Electric heat operation
Do Not Diagnose Refrigerant Charge Through a Known Airflow Problem
Correct major airflow abnormalities first.
6. Measure Supply and Return Air Temperatures
Temperature measurements help determine whether the indoor equipment is transferring heat.
A Technician Can Compare:
- Return-air temperature
- Supply-air temperature
- Room temperature
- Outdoor temperature
Temperature Difference Is Not a Universal Pass-or-Fail Number
It changes with:
- Operating mode
- Compressor capacity
- Airflow
- Outdoor conditions
- Indoor load
- Backup heat operation
Variable-Speed Heat Pumps Complicate Simple Temperature Rules
A system running at low capacity may have a different supply-air temperature than the same system operating near maximum output.
7. Measure Duct Static Pressure
For a ducted system, a manometer can measure the resistance the blower is operating against.
Measurements Can Help Identify:
- Restrictive filter
- Dirty indoor coil
- Undersized return duct
- Supply restriction
- Closed damper
- Improper blower configuration
Total External Static Pressure Is Particularly Useful
The measured value can be compared with:
- Manufacturer blower tables
- Air handler limits
- Commissioning data
High Static Pressure Can Exist Even When Air Still Comes From the Registers
A variable-speed blower may work harder to maintain airflow, producing:
- More noise
- Higher fan power
- Reduced available airflow at its operating limit
8. Verify Blower or Indoor-Fan Operation
For Central Systems, Check:
- Blower command
- Motor operation
- Blower wheel condition
- Configured airflow
- Motor current or electronic data where applicable
For Ductless Systems, Check:
- Indoor fan speed
- Cross-flow fan condition
- Fan feedback
- Louvre operation
Not Every Blower Motor Uses a Traditional Capacitor
Modern air handlers commonly use electronically controlled motors, while some equipment uses conventional PSC motors.
A Running Motor Does Not Prove Correct Airflow
The blower wheel, duct system and controls still affect delivered air volume.
9. Inspect Indoor and Outdoor Heat Pump Coils
Look for:
- Dirt
- Debris
- Ice
- Corrosion
- Physical damage
- Airflow obstruction
Indoor Coil Problems Can Affect:
- Airflow
- Cooling
- Heating
- Dehumidification
- Condensate drainage
Outdoor Coil Problems Can Affect:
- Heat absorption in winter
- Heat rejection in summer
- Defrost
- Refrigerant pressures
A Dirty Coil Is Not Automatically a Refrigerant Problem
Cleaning and airflow correction may be required before sealed-system conclusions are reliable.
10. Test Condensate Drainage and Safety Switches
During cooling, the technician may inspect:
- Drain pan
- Primary drain
- Trap
- Condensate pump
- Float switch
- Secondary pan
Test Actual Drainage
A drain that looks open may still:
- Drain slowly
- Have improper slope
- Contain a partial blockage
- Fail under heavy condensate load
Test Safety Devices
An overflow switch should stop or signal the equipment according to the installation design.
Do Not Bypass a Drain Safety to Complete Diagnosis
The water problem should be corrected.
11. Verify Electrical Supply Voltage
A heat pump cannot be diagnosed properly without confirming that its electrical supply is suitable.
Qualified Testing Can Include:
- Outdoor-unit voltage
- Indoor-unit voltage
- Control voltage
- Transformer output
- Voltage under operating load
Electrical Problems Can Mimic HVAC Failures
Examples include:
- Low voltage
- Loose termination
- Failed disconnect
- Damaged breaker
- Control-transformer fault
Do Not Diagnose an Inverter Board Before Checking Its Power Supply
The board can only operate correctly when its required electrical conditions are present.
12. Measure Current and Electrical Loads
A clamp meter or manufacturer diagnostic system can help evaluate operating electrical loads.
Measurements Can Include:
- Compressor current
- Outdoor fan current
- Blower current
- Electric heat current
Current Must Be Interpreted in Context
Variable-speed equipment changes its electrical input according to:
- Capacity demand
- Outdoor conditions
- Indoor conditions
- Fan speed
A Low Current Reading Does Not Automatically Mean Weak Equipment
The system may simply be operating at low capacity.
An Abnormal Reading Can Help Locate:
- Motor problem
- Electric heat stage failure
- Compressor problem
- Electrical supply issue
13. Inspect Wiring, Terminals and Disconnects
A Technician May Inspect For:
- Loose connections
- Heat damage
- Corrosion
- Damaged insulation
- Improper field wiring
- Communication-wire problems
Electrical Connections Can Fail Intermittently
Heat and vibration can make a poor connection behave differently:
- At startup
- At high capacity
- During cold weather
- After extended operation
Visual Inspection Is Not Enough for Every Fault
Voltage-drop, continuity or other electrical testing may be needed.
14. Test Temperature and Pressure Sensors
Modern heat pumps depend heavily on electronic sensors.
Possible Sensors Include:
- Indoor air temperature
- Indoor coil temperature
- Outdoor air temperature
- Outdoor coil temperature
- Compressor discharge temperature
- Refrigerant pressure transducers
A Sensor Fault Can Be:
- Failed sensor
- Loose connector
- Damaged wire
- Incorrect resistance
- Control-board input problem
Compare Sensor Data With Independent Measurements
If the controller reports an outdoor temperature far from actual outdoor conditions, that discrepancy can help locate the fault.
15. Verify Indoor and Outdoor Fan Operation
Heat transfer depends on both sides of the refrigeration circuit moving air correctly.
Check:
- Fan command
- Actual fan operation
- Fan speed
- Motor feedback
- Physical obstruction
- Blade or wheel condition
An Outdoor Fan Can Stop Normally During Defrost
Context matters before declaring a fan failure.
A Fan Can Spin but Still Be Faulty
Problems can include:
- Incorrect speed
- Intermittent operation
- Motor overheating
- Electronic feedback error
16. Evaluate Compressor and Inverter Operation
Variable-speed heat pumps can provide extensive compressor operating data.
Possible Diagnostic Information Includes:
- Requested compressor speed
- Actual compressor speed
- Compressor current
- Discharge temperature
- Inverter fault history
- Protection events
An Inverter Fault Does Not Automatically Mean the Inverter Board Failed
Other conditions can trigger protection, including:
- Abnormal voltage
- High refrigerant pressure
- High discharge temperature
- Compressor problem
- Cooling or airflow fault
Internal Inverter Testing Is Professional Work
These systems can contain hazardous voltage and stored electrical energy.
17. Evaluate Refrigerant-System Conditions
When symptoms indicate a refrigeration problem, the technician may evaluate the sealed system.
Depending on Equipment, Tests Can Include:
- Refrigerant pressures
- Pipe temperatures
- Superheat
- Subcooling
- Discharge temperature
- Electronic expansion-valve position
- Manufacturer service data
Pressure Alone Is Not Refrigerant Charge
Pressure depends on:
- Indoor conditions
- Outdoor conditions
- Airflow
- Compressor capacity
- Operating mode
Variable-Speed Equipment Often Requires Manufacturer-Specific Procedures
A rule developed for a fixed-speed air conditioner may not be appropriate for an inverter heat pump.
If a Leak Is Suspected
Diagnosis may progress to leak detection rather than simply adding refrigerant.
18. Check Heat Pump Reversing-Valve Operation
The reversing valve changes refrigerant direction between heating and cooling.
Possible Symptoms of a Reversing Problem Include:
- No heating but cooling works
- No cooling but heating works
- Incorrect coil temperatures
- Abnormal refrigerant conditions
The Valve Itself Is Not Always the Cause
Also test:
- Solenoid coil
- Thermostat command
- Control-board output
- Wiring
Do Not Replace a Reversing Valve Based on One Symptom
It is a significant sealed-system repair and should be confirmed carefully.
19. Evaluate Heat Pump Defrost Operation
For winter icing complaints, diagnosis should distinguish normal frost from abnormal ice accumulation.
Evaluate:
- Outdoor coil condition
- Outdoor fan operation
- Outdoor temperature sensor
- Coil sensor
- Defrost initiation
- Defrost termination
- Reversing-valve operation
Observe an Actual Defrost When Possible
Useful information includes:
- Whether frost clears
- How the outdoor fan behaves
- Whether backup heat operates
- Whether a fault code appears
Heavy Ice Is a Symptom, Not a Diagnosis
Possible causes include airflow, sensor, control and refrigeration problems.
20. Test AUX and Emergency Heat
Central full-electric heat pumps may rely on resistance heat during peak heating demand, defrost or compressor failure.
Test:
- Thermostat call
- Heat stages
- Relays or sequencers
- High-temperature limits
- Current draw
- Blower airflow
One Heat Stage Can Fail While Others Work
The homeowner may notice:
- Slow cold-weather recovery
- Weak Emergency Heat
- Uneven staging
Unexpected AUX Heat Use Is Also Diagnostic Information
Excessive supplementary heating can indicate that the heat pump itself is not delivering expected capacity.
21. Check Communication, Multi-Zone Controls and Zoning
Modern systems can fail because components are not exchanging information correctly.
Central Communicating Systems
Check communication between:
- Thermostat
- Air handler or furnace
- Outdoor unit
- Zone panel
Multi-Split Systems
Check:
- Indoor-unit addressing
- Communication wiring
- Zone mode conflicts
- Local sensors
- Electronic expansion valves
One Zone Can Fail Without the Entire System Failing
This is valuable information for narrowing the diagnostic area.
22. Reproduce the Fault and Verify the Repair
A diagnosis is much stronger when the technician can reproduce the original symptom.
After a Repair, Test the Same Condition Again
For example:
- Restart heating after correcting a blower fault.
- Run cooling after clearing a condensate problem.
- Operate multiple zones after repairing communication wiring.
- Confirm defrost after correcting a sensor problem.
Clearing the Code Is Not the Final Test
The system should demonstrate normal:
- Startup
- Operation
- Airflow
- Heating or cooling output
- Shutdown
Record Final Measurements
Useful final data can become the baseline for future service.
Does Every Heat Pump Service Call Require Refrigerant Gauges?
No.
Gauge Connection May Be Appropriate When:
- Refrigerant performance is genuinely in question.
- A leak is suspected.
- A sealed-system repair has been completed.
- The manufacturer procedure requires pressure measurements.
Gauge Connection May Be Unnecessary for:
- Dirty filter
- Failed thermostat
- Condensate pump failure
- Loose communication wire
- Blower problem
Modern Systems Can Provide Electronic Refrigeration Data
Some communicating heat pumps allow technicians to read system sensors and operating parameters through manufacturer diagnostic software.
Unnecessary Refrigerant-Circuit Access Has No Diagnostic Benefit
Testing should be driven by evidence rather than ritual.
Common Heat Pump Diagnostic Tools
| Tool | Typical Purpose |
|---|---|
| Digital multimeter | Voltage, resistance and control-circuit testing |
| Clamp meter | Electrical current measurement |
| Manometer | Duct static pressure measurement |
| Temperature probes | Air and refrigerant-pipe temperature measurement |
| Psychrometer | Temperature and humidity measurements |
| Airflow instruments | Air velocity or airflow assessment |
| Refrigerant manifold or electronic probes | Sealed-system pressure measurement when required |
| Electronic leak detector | Locating suspected refrigerant leakage |
| Manufacturer diagnostic software | Fault history and real-time operating data |
The Tool Does Not Make the Diagnosis
Measurements need to be interpreted using:
- Manufacturer data
- Operating conditions
- System configuration
- The original symptom
What Technicians Test on Ducted Heat Pumps
Ducted systems require diagnosis of both equipment and air distribution.
Typical Areas Include:
- Thermostat
- Air handler or furnace
- Outdoor unit
- Filter
- Blower
- Indoor coil
- Static pressure
- Ductwork
- Condensate drain
- Backup heat
Airflow Measurements Are Particularly Important
Refrigeration equipment can be operating correctly while the duct system prevents adequate comfort.
Room-Level Symptoms Matter
If only one room is uncomfortable, check:
- Branch duct
- Damper
- Return path
- Register
before condemning central equipment.
What Technicians Test on Ductless Heat Pumps
Indoor Unit
Possible checks include:
- Filters
- Indoor coil
- Cross-flow fan
- Room sensor
- Coil sensors
- Drainage
- Electronic expansion valve
Outdoor Unit
Possible checks include:
- Compressor
- Outdoor fan
- Coil
- Sensors
- Inverter
- Refrigeration conditions
Controller Fault Patterns Matter
Ductless systems may communicate faults through:
- LED flashes
- Wired controller
- Remote control
- Manufacturer app
What Technicians Test on Multi-Zone Heat Pumps
A multi-zone system adds another diagnostic question: is the problem local to one zone or shared by the whole system?
If One Head Fails
Investigate that zone’s:
- Communication
- Fan
- Sensors
- Drain
- Electronic expansion valve
If Every Zone Fails
Investigate shared:
- Outdoor unit
- Power
- Communication
- Refrigeration circuit
Test Different Zone Combinations
Some intermittent faults appear only when several indoor units request capacity simultaneously.
What Technicians Test on Full-Electric Heat Pump Systems
In addition to normal heat-pump operation, test the electric supplementary heating system.
Important Questions Include:
- Does the compressor provide normal heating?
- Does AUX Heat stage correctly?
- Does Emergency Heat work?
- Is the blower providing sufficient airflow?
- Are heat-kit electrical circuits operating correctly?
Electric Heat Can Hide a Compressor Fault
A home can remain warm while using significantly more electricity because resistance backup has replaced normal heat-pump heating.
What Technicians Test on Dual-Fuel Heat Pump Systems
A dual-fuel service call can involve both refrigeration and gas-heating equipment.
Check the Heat Pump Side
Including:
- Compressor
- Outdoor fan
- Refrigeration operation
- Defrost
Check the Shared Airflow
The furnace blower also serves the heat pump coil in many systems.
Check Changeover Controls
Review:
- Outdoor-temperature sensing
- Balance-point settings
- Furnace lockout
- Heat-pump lockout
Gas-Furnace Diagnosis Requires Appropriate Gas Qualification
Combustion, gas pressure, burners, heat exchanger and venting are separate safety-critical areas.
How Are Intermittent Heat Pump Problems Diagnosed?
Intermittent failures are often the most time-consuming service calls because the system may work perfectly while the technician is present.
Useful Evidence Includes:
- Fault history
- Homeowner photos
- Videos
- Thermostat runtime history
- Outdoor temperature
- Time of failure
Look for Patterns
Does it fail:
- At high compressor speed?
- During defrost?
- After several hours?
- During rain?
- When all zones operate?
- After a power interruption?
Do Not Replace Parts Merely Because the Fault Cannot Be Reproduced
Use stored data and repeatable evidence where possible.
What if the Heat Pump Works Normally When the Technician Arrives?
This does not necessarily mean the homeowner imagined the problem.
The Technician Can Still:
- Review fault history
- Check electrical connections
- Inspect filters and coils
- Test static pressure
- Review sensor values
- Check thermostat history
- Look for evidence of water or icing
Sometimes the Correct Result Is “No Fault Reproduced Yet”
That is more responsible than inventing a failed component.
Create a Monitoring Plan
The homeowner can record:
- Error code
- Outdoor temperature
- Operating mode
- Zone status
- Noise or video evidence
when the symptom returns.
Safe Homeowner Checks Before a Heat Pump Service Call
- Check Heat or Cool mode.
- Check the thermostat setpoint.
- Check Fan Auto vs Fan On.
- Inspect the user-accessible filter.
- Make sure registers are not heavily blocked.
- Look for outdoor snow or loose debris.
- Check for visible indoor water leakage.
- Look for obvious ice without opening equipment.
- Photograph fault codes.
- Listen for abnormal sounds.
- Check the electrical panel visually.
One Observation Can Save Diagnostic Time
For example, telling the technician “the indoor blower runs but the outdoor unit stops after five minutes and shows this code” is considerably more useful than “it does a weird thing.”
What Should Homeowners Not Test?
- Do not open energized electrical compartments.
- Do not test inverter boards.
- Do not connect refrigerant gauges.
- Do not add refrigerant.
- Do not bypass pressure protection.
- Do not bypass float switches.
- Do not bypass electric heat limits.
- Do not repeatedly reset tripping breakers.
- Do not move communication wiring.
- Do not force the reversing valve.
- Do not alter defrost parameters.
- Do not randomly change installer thermostat settings.
Electrical and Refrigerant Work Require Training
Modern inverter heat pumps combine:
- Line voltage
- Electronic power conversion
- Pressurized refrigerant
- Moving machinery
inside the same system.
How Does Diagnosis Turn Into a Repair Recommendation?
After Testing, the Technician Should Be Able to Explain:
- What symptom was confirmed
- What measurement was abnormal
- What component or condition is causing the problem
- What repair is recommended
- Whether another defect contributed
Examples
Weak airflow: high static pressure caused by restrictive return ductwork.
Water leakage: frozen indoor coil caused by blower failure.
High electricity use: outdoor heat pump locked out while electric AUX Heat carried the load.
Outdoor icing: failed outdoor coil sensor preventing correct defrost control.
The Symptom and Root Cause Are Often Different
Replacing the symptom without correcting the cause can lead to another failure.
When Does a Second Heat Pump Diagnosis Make Sense?
A second opinion can be reasonable before a major repair or complete replacement when:
- The diagnosis was made without relevant testing.
- A compressor was condemned without supporting electrical and refrigeration measurements.
- A refrigerant leak was diagnosed without leak evidence.
- Several expensive parts are proposed at once.
- The recommended repair approaches replacement cost.
- The explanation is inconsistent with the symptoms.
A Second Opinion Is Less Useful When the Failure Is Obvious and Documented
Examples can include:
- Clearly failed blower motor
- Cracked drain pan
- Confirmed leaking coil
- Burned electrical component
Keep the First Diagnostic Information
Photos, fault codes and measurements can help the next technician understand what has already been tested.
How Much Does a Heat Pump Diagnostic Service Call Cost?
Diagnostic charges and repair costs vary because the time and testing required for a clogged drain are very different from an intermittent inverter, refrigerant or communication problem.
Bernoulli Existing-System Diagnostic Appointment
Bernoulli Heating and Cooling’s current diagnostic appointment charge for an existing heat pump is $135.
The diagnostic appointment is intended to identify the operating problem and determine the appropriate next repair step.
The $135 Diagnostic Charge Does Not Include:
- Repair labour
- Replacement parts
- Electrical materials
- Cleaning materials
- Refrigerant
- Additional repair materials
New Heat Pump Installation or Replacement
New heat pump installation and replacement estimates are free.
The $135 diagnostic charge applies to troubleshooting an existing system rather than preparing a new-system installation or replacement estimate.
What Should Be Documented After a Heat Pump Diagnosis?
A Useful Service Record Can Include:
- Equipment model and serial numbers
- Homeowner complaint
- Error codes
- Measured electrical readings
- Airflow or static-pressure results where relevant
- Temperature measurements
- Observed refrigerant data where relevant
- Failed component or identified condition
- Recommended repair
After Repair
Record:
- Parts replaced
- Repair performed
- Final operating test
- Relevant final measurements
Keep Service Records With Warranty Documents
They can be useful for:
- Future diagnosis
- Warranty history
- Repair-vs-replacement decisions
Heat Pump Diagnostic Service in Metro Vancouver and Fraser Valley
Bernoulli Heating and Cooling provides heat pump troubleshooting and diagnostic service across Metro Vancouver and Fraser Valley.
Depending on the complaint and equipment, diagnosis can include thermostat and fault-history review, airflow and static pressure, electrical testing, blower and fan operation, sensors, condensate drainage, defrost, supplementary heating and refrigerant-system evaluation where required.
The current diagnostic appointment charge for an existing heat pump is $135. Repair labour, replacement parts, electrical materials, cleaning materials and refrigerant are separate.
New heat pump installation and replacement estimates are free.
Call 604-518-4438 or email heatingbernoulli@gmail.com.
For local heat pump installation planning, review:
Heat Pump Service Call: Frequently Asked Questions
What happens during a heat pump service call?
The technician confirms the complaint, identifies the equipment, reviews controls and fault history, performs relevant measurements and determines the likely cause before recommending repair.
Is a heat pump service call the same as maintenance?
No. Diagnosis investigates an existing problem. Maintenance is routine preventive service.
Is commissioning the same as diagnosis?
No. Commissioning verifies that newly installed or modified equipment performs correctly.
Does every diagnostic call require every test in this guide?
No. Testing should match the symptom.
Should the technician listen to my description first?
Yes. The timing and conditions of the symptom can significantly narrow the diagnostic process.
Should I photograph the error code?
Yes.
Should I reset the heat pump before the technician arrives?
Avoid repeated resets. Record fault information first.
What if the system starts working again?
Stored faults, photos and operating history can still support diagnosis.
Can technicians see old heat pump error codes?
Many modern systems retain some fault history.
Are error codes enough to diagnose the repair?
Not always.
Why not?
A code often identifies a detected condition rather than proving which physical component caused it.
Does a sensor code always mean the sensor is bad?
No. Wiring, connectors or the control board can also be involved.
Does a pressure code mean the heat pump needs refrigerant?
No.
Does a compressor code mean the compressor is dead?
No. Electrical, control and refrigerant conditions can trigger compressor-related protection.
Should the technician check the filter?
Yes, especially for airflow, heating, cooling or icing complaints.
Can a dirty filter change refrigerant readings?
Yes. Restricted airflow changes coil and refrigeration operating conditions.
Should airflow be fixed before refrigerant charge is diagnosed?
Major airflow problems should generally be corrected or accounted for before charge conclusions are made.
What is static pressure?
It is a measurement used to evaluate the resistance the ducted blower is operating against.
What tool measures static pressure?
A manometer is commonly used.
Why measure static pressure?
It can identify restrictive filters, ducts, coils or other airflow problems.
Does every ducted service call need static-pressure testing?
Not necessarily, but it is highly useful when airflow, noise or distribution is part of the complaint.
Can a blower be running but airflow still be wrong?
Yes.
Why?
Dirty components, restrictive ducts, incorrect blower settings or a damaged wheel can reduce actual air delivery.
Does every blower have a capacitor?
No.
Do modern ECM blowers use the same diagnosis as older PSC motors?
No. Their motor and electronic control systems differ.
Should voltage be measured during diagnosis?
It is appropriate for electrical or operating faults and is part of professional HVAC electrical evaluation.
Why measure current?
Current measurements can help evaluate motors, compressors and electric heat stages.
Can current change with compressor speed?
Yes. Variable-capacity equipment changes electrical input with load.
Can a technician tell if AUX Heat is running?
Yes, through thermostat status, electrical measurements and system controls.
Why does AUX Heat matter during diagnosis?
It can keep the house warm even when the compressor is not providing normal heating.
Can excessive AUX Heat explain a high electricity bill?
Yes.
Should Emergency Heat be tested?
Where the system has Emergency Heat, its operation can be verified as part of relevant diagnostic or maintenance work.
Does every heat pump have Emergency Heat?
No.
Do ductless heat pumps normally have electric heat kits?
Most standard residential ductless systems do not use a central electric resistance heat kit.
Do technicians always connect refrigerant gauges?
No.
Why would a technician not connect gauges?
The problem may clearly involve controls, drainage, airflow or electrical components rather than the sealed refrigerant circuit.
Can gauges introduce risk?
Opening service connections should have a diagnostic purpose and follow proper refrigeration procedures.
Can refrigerant charge be diagnosed by pressure alone?
No.
What else is required?
Operating mode, indoor and outdoor conditions, airflow, pipe temperatures and manufacturer procedures can all matter.
What is superheat?
It describes how far refrigerant vapour temperature is above its saturation temperature at the measured pressure.
What is subcooling?
It describes how far liquid refrigerant temperature is below its saturation temperature at the measured pressure.
Does every heat pump use the same superheat or subcooling target?
No.
Can variable-speed heat pumps require different charging procedures?
Yes.
Can diagnostic software replace gauges?
Some manufacturer tools provide extensive electronic operating data, but the necessary method depends on the fault and equipment.
Can a technician see compressor speed?
Some communicating and inverter systems provide actual or commanded compressor-speed data.
Can a technician see electronic expansion-valve position?
Some manufacturer diagnostic platforms provide that information.
What is a reversing valve?
It changes refrigerant flow direction so the heat pump can switch between heating and cooling.
How is a reversing-valve problem diagnosed?
The technician can evaluate control signals, coil operation and refrigeration temperatures and pressures.
Should a reversing valve be replaced based only on no heating?
No.
How is a defrost problem diagnosed?
By evaluating coil icing, sensors, outdoor fan, reversing operation, controls and the actual defrost sequence.
Does ice on the outdoor unit always mean defrost is broken?
No. Some frost is normal during heating.
Can the technician force a defrost test?
Some equipment provides manufacturer-defined service procedures for testing defrost operation.
Can a dirty outdoor coil affect diagnosis?
Yes.
Can a failed outdoor fan affect refrigerant pressures?
Yes.
Can a failed indoor fan affect refrigerant pressures?
Yes.
Should coils be inspected before sealed-system diagnosis?
Yes when airflow or heat-transfer problems may affect the measurements.
Should condensate drainage be checked during cooling complaints?
Yes, particularly when water leakage or shutdown is involved.
Can a blocked drain shut off the heat pump?
Yes when an overflow switch is wired into the system controls.
Can a blank thermostat be caused by a condensate switch?
Yes on some installations.
Should the technician bypass the float switch to make the unit run?
The underlying drainage problem should be corrected rather than leaving safety protection bypassed.
Can wiring cause intermittent failures?
Yes.
Why would wiring fail only sometimes?
Heat, vibration and changing electrical load can expose marginal connections intermittently.
Can a power outage create useful fault history?
Yes. Equipment can store communication or power-related faults after an interruption.
Can the technician diagnose a heat pump that currently works?
Sometimes, using fault history, measurements and evidence from the homeowner.
What does “could not reproduce fault” mean?
It means the reported symptom did not occur during the diagnostic visit.
Does that prove there is no problem?
No.
Should the technician replace a likely part anyway?
Not without sufficient evidence when further diagnosis or monitoring is practical.
Can video help diagnose noises?
Yes.
Should I record the outdoor temperature when a fault happens?
Yes, especially for heating and defrost problems.
Should I record which multi-zone heads are operating?
Yes.
Why does multi-zone diagnosis take longer?
Technicians may need to distinguish a fault in one indoor unit from shared outdoor or communication problems.
Can one ductless indoor unit fail while others work?
Yes.
Can one outdoor-unit fault stop every zone?
Yes.
Can mode conflict look like a fault?
Yes on many conventional multi-zone systems.
What extra tests are needed on a dual-fuel system?
The technician may need to evaluate heat-pump operation, furnace operation, shared airflow and changeover controls.
Does a gas furnace require different qualifications?
Gas combustion and fuel-system work must be performed under the applicable qualification and safety requirements.
Can the furnace blower cause heat-pump problems?
Yes. In many dual-fuel systems it provides airflow across the heat-pump indoor coil.
Should both heating and cooling be tested after a repair?
Where conditions and manufacturer procedures permit, complete operating verification is useful.
Should the original symptom be reproduced after repair?
Yes whenever practical.
Why?
It provides evidence that the repair actually corrected the reported problem.
Is clearing the error code enough?
No.
Should the technician provide measurements?
For significant diagnostic findings, relevant measurements help document how the conclusion was reached.
Do I need a printed service report?
A written or electronic service record is useful for future repairs and warranty history.
What information should be on it?
Equipment identification, complaint, diagnosis, work performed and relevant test results are useful.
Should model and serial numbers be recorded?
Yes.
Should I keep invoices and service records?
Yes.
Can maintenance records help warranty claims?
They can be useful when warranty terms or manufacturers require evidence of installation or service history.
When should I request a second opinion?
It can make sense before an expensive compressor, coil, inverter or complete-system replacement when the diagnosis is uncertain or poorly supported.
Does a compressor fault automatically mean replacement?
No.
Does an inverter-board fault automatically mean replacement?
No.
Does a refrigerant leak mean the entire heat pump needs replacing?
No. Age, leak location, repair cost, refrigerant, warranty and overall equipment condition should be considered.
Can diagnosis show that the real problem is the ductwork?
Yes.
Can diagnosis show that the heat pump itself is fine?
Yes. Thermostat, duct, electrical or building conditions can create comfort complaints even when the refrigeration equipment operates normally.
Can a heat pump be incorrectly sized even if it has no mechanical fault?
Yes.
Can a service technician fix oversizing with a setting?
Some control adjustments may improve operation, but significant equipment oversizing cannot always be corrected through settings alone.
Can a thermostat problem look like a refrigerant problem?
Yes.
Can a dirty filter look like a refrigerant problem?
Yes.
Can high static pressure look like a blower failure?
Yes.
Can a sensor failure look like a compressor problem?
Yes, depending on the protection logic.
Why is systematic diagnosis important?
Several different faults can produce similar homeowner symptoms.
How much does Bernoulli charge for an existing heat pump diagnostic appointment?
The current diagnostic appointment charge is $135.
Does the $135 include the repair?
No. Repair labour, replacement parts, electrical materials, cleaning materials, refrigerant and other required materials are separate.
Does the $135 include refrigerant?
No.
Does every diagnosis require refrigerant service?
No.
Are new heat pump installation estimates free?
Yes.
Is the $135 charge applied to a new installation estimate?
No. New heat pump installation and replacement estimates are currently free. The $135 charge applies to diagnostic appointments for existing systems.