Heat Pump Repair
Accurate Diagnostics · Common Parts In Stock · All Brands Serviced
Our Approach to Heat Pump Repair
How a Heat Pump Works
- Outdoor unit — fan and compressor extract heat from outside air
- Reversing valve — switches the system between heating and cooling
- Line set — carries hot, high-pressure refrigerant indoors
- Indoor coil — releases heat into the airstream
- Warm air — the blower delivers it to the room
When your heat pump stops working or is not performing like it should, J&R Mechanical Services provides fast, accurate diagnostics and honest repairs. We fix the actual problem — not just the symptoms.
Heat pump issues can range from simple fixes like a dirty filter or tripped breaker to more complex problems like refrigerant leaks, compressor failures, or control board malfunctions. Our technicians diagnose accurately the first time so you get the right repair without paying for unnecessary parts.
We service all major heat pump brands. We carry common replacement parts to complete most repairs in a single visit. Regular heat pump maintenance can help prevent many common repair issues before they start.
If your heat pump is beyond repair or the cost of fixing it does not make sense, we will tell you honestly and help you evaluate replacement options.
Common Heat Pump Problems
The calls we see most: a unit that is icing over and never defrosting (often a defrost sensor, board, or refrigerant issue rather than "normal winter"), indoor heads blowing lukewarm air in heating mode, error codes flashing on the display, water dripping from an indoor unit (a clogged condensate line), outdoor units that rattle or grind, and systems that simply will not turn on after a power blip.
Winter weather adds its own failure modes. Outdoor coils take a beating from snow load and ice fall from roofs, small animals love the warmth of control boards, and units mounted too low get buried in a storm and starve for airflow. Our technicians see these patterns constantly, which is why our diagnosis starts with the likely culprits instead of a parts-swapping expedition billed to you by the hour.
Should You Repair or Replace Your Heat Pump?
Honest math: if your system is under ten years old and the fix is a sensor, board, motor, or condensate problem, repair is almost always the right call. If it is well past its rated service life, needs a compressor, or has a major leak on an older refrigerant, replacement usually wins once you count efficiency gains.
Our technicians are not commissioned, so you get that math straight. We have no quota pushing us toward the replacement answer — repairing your unit well is how we earn your next call.
Mini-Split Error Codes by Brand, and What to Check First
When a mini-split finds a fault, it usually says so with a code on the remote or a pattern of blinking lights on the indoor unit. The codes are not shared across brands, and they can change between model lines from the same brand.
Each table below comes from the manufacturer's own manual for one named model line. All five brands have models on Efficiency Maine's list of rebate-eligible heat pumps. Find the model number on your indoor unit's label and check that it matches before you rely on a code.
Check These Before You Call
- Make sure the breaker is on. After a restart, wait about 3 minutes. Many units, including the Mitsubishi and Carrier lines below, hold off restarting for 3 minutes to protect the compressor.
- Check the remote: batteries in the right way, the right mode, and no timer set to shut the unit off. In winter, use Heat, not Auto. Efficiency Maine notes that Auto can switch to cooling on a sunny winter day.
- Look at the filters and make sure nothing is blocking the air inlet or outlet on the indoor or outdoor unit. Close any open windows or doors near the unit.
- A heating pause of up to about 10 minutes on a cold, damp day can be a normal defrost cycle, not a failure.
- On a Carrier 45MAHAQ, "FC" on the display means forced cooling mode. The manual states it is not an error code.
Stop using the unit and call for service if water leaks from the indoor unit, the operation lamp keeps blinking, the breaker trips repeatedly, or you suspect a refrigerant leak. Mitsubishi warns that refrigerants may not have an odor, so a leak code matters even if you smell nothing. Carrier says to call a technician as soon as possible for its leak codes.
Mitsubishi Electric M-Series (MSZ-GX Wall Units)
If the operation lamp blinks, point the remote at the unit and press CHECK with a fine-tipped object. With "00" showing, two beeps means no error and one beep means there is one. Step through the codes; two beeps marks the code the unit has.
| Code | What the manual says it means |
|---|---|
| E6, E7 | Serial signal (indoor unit) |
| E8, E9, EC | Indoor/outdoor communication, receiving error |
| EE | Indoor and outdoor unit refrigerant do not match |
| FL | Refrigerant leakage abnormality of the indoor unit |
| P1 | Room temperature thermistor |
| P2, P9 | Indoor coil thermistor |
| P4 | Drain sensor |
| Pb | Indoor fan motor |
| U3 | Outdoor thermistors (discharge or defrost or fin) |
| U4 | Outdoor thermistors (circuit board or ambient or heat exchanger) |
| UP | Outdoor power system |
Fujitsu Halcyon RLS2 Wall Units
These units show faults by blinking the green OPERATION lamp and the orange TIMER lamp a set number of times, while the ECONOMY lamp blinks continuously. An optional wired remote shows a two-digit code instead. Newer Fujitsu lines, such as the RLS3H, may differ, so check your own model's manual.
| OPERATION blinks | TIMER blinks | Wired remote | Error |
|---|---|---|---|
| 1 | 1 | 11 | Serial communication error |
| 4 | 1 | 41 | Indoor room thermistor error |
| 5 | 1 | 51 | Indoor unit fan motor error |
| 6 | 2 | 62 | Outdoor unit main circuit board error |
| 7 | 4 | 74 | Outdoor thermistor error |
| 9 | 4 | 94 | Over current error |
| 9 | 7 | 97 | Outdoor unit fan motor error |
| 9 | 9 | 99 | 4-way valve error |
| 10 | 1 | A1 | Discharge temperature error |
Daikin Aurora R-32 Wall Units
When the operation lamp blinks, hold CANCEL for about 5 seconds, then point the remote at the unit and press it repeatedly. A short beep means no match and a long beep marks the unit's code. For E7 and L3 to L5, the manual lets owners switch off the breaker, clear anything blocking the outdoor unit, and restart. Other codes need service.
| Code | What the manual says it means |
|---|---|
| UA | Indoor/outdoor unit combination error |
| U0 | Refrigerant shortage |
| U2 | Main circuit voltage drop or overvoltage |
| U4 | Transmission problem between indoor and outdoor units |
| A5 | High-pressure control or freeze protection |
| A6 | Fan motor error |
| E7 | DC fan motor error (outdoor fan stopped) |
| F3 | Discharge pipe high-temperature control |
| L3, L4, L5 | Outdoor unit overheated inside and stopped |
Carrier 45MAHAQ Ductless High-Wall Units
The code appears on the indoor unit's display. The manual abbreviates the outdoor unit as ODU and the indoor unit as IDU. For its leak codes, the unit may run in TURBO mode and beep until the code clears, which the manual calls normal.
| Code | What the manual says it means |
|---|---|
| EC07 | Outdoor unit fan speed out of control |
| EH03 | Indoor unit fan speed out of control |
| EH0E | Water level alarm malfunction |
| EH60 | Indoor room temperature sensor (T1) error |
| EHC1 | Refrigerant sensor detects leakage |
| EL01 | Indoor and outdoor unit communication error |
| EL0C | System lacks refrigerant |
| PC03 | Pressure protection (low or high pressure) |
| PC0L | Low ambient temperature protection |
LG: Look Up the Code by Model and Serial Number
LG has models on Efficiency Maine's rebate-eligible list, including single-zone and multi-zone ductless lines. Unlike the four manuals above, LG's manual library is not browsable online — it only returns a manual after you enter the exact model and serial number from the nameplate on the indoor or outdoor unit. We were not able to open a specific LG model's fault-code table through that lookup, so we are not listing codes here rather than guess at them.
If your LG unit is showing a code or a blink pattern, write down the code (or count the blinks) and the full model and serial number from the nameplate before you call. That combination is what LG support or a technician needs to look up the exact fault.
Sources: Mitsubishi Electric MSZ-GX06/09/12/15NL operating instructions (DG79A0JKH01) · Fujitsu General ASU/AOU9, 12, 15RLS2 service instruction (archived copy) · Daikin FTX09/12/15WMVJU9 operation manual (3P686870-1, French edition) · Carrier 45MAHAQ owner's manual (45MAHA-01OM) · Efficiency Maine heat pump user tips · Efficiency Maine Residential List of Rebate-Eligible Heat Pumps (as of September 22, 2026)
Brand names and logos are trademarks of their respective owners, shown only to identify the equipment discussed. J&R Mechanical Services is an independent contractor and is not affiliated with or endorsed by these manufacturers.
Local & Independent
J&R Mechanical Services is an independent contractor — not a national franchise. Our technicians are not commissioned salespeople. We do the work you called us for, do it right, and earn the next call.
More Heat Pumps & Mini-Splits Services
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Heat Pump Repair FAQs
Why is my heat pump covered in ice?
Light frost on the outdoor coil is normal — the unit runs periodic defrost cycles to clear it. Solid ice that never clears is not normal, and usually points to a failed defrost sensor or board, low refrigerant, or blocked airflow. Shut the unit off and have it diagnosed before the ice damages the fan or coil.
Why is my heat pump blowing cold air in heat mode?
Check the remote is actually in heat mode and the filters are clean first. If those are fine, the usual causes are low refrigerant from a leak, a failing reversing valve, or a compressor issue — all of which need a technician with gauges to confirm.
How much does heat pump repair cost?
It depends on what has failed. Simple fixes like condensate clogs, sensors, or capacitors are typically inexpensive; board replacements and refrigerant leak repairs cost more. We always quote before we repair, so you can decide with the real number in front of you.
Do you service heat pumps you did not install?
Yes. We repair all major brands regardless of who installed the system.
Is it worth repairing an older heat pump?
Often yes, if the repair is minor and the system was installed well. Once a unit is well past its rated service life or facing a compressor or major refrigerant repair, replacement usually makes more financial sense. We give you both numbers and let you choose.
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