Heat pump

On left side of the control board will be the test terminals, short them with screwdriver and the diagnostic light will flash an error code

No power

Starter or breaker tripped possible faulty compressor start windings, a hard start kit can be used to make unit work but with my experience it only lasts a few months.
2 Flash high-pressure problems red wires run to HP switch

Water Condenser should have 10-degree difference between water going in and water going out.
Refrigerant charge could be over charged check subcooling.
Faulty high-pressure switch test switch at normal pressures it should be normally closed.
In heating mode possible low/no airflow over the Evaporator.
Faulty TXV bulb loss of charge or plug/stuck valve
My experience 1
Refrigerant 410a
cooling H-600 PSI L-50 PSI and dropping frost between TXV and air coil, trip on high pressure Heating H-350 PSI L-75 PSI cold between TXV and water condenser, trip on water coil low temperature Found TXV stuck closed I replaced both filter/dryers, TXV, vacuum to 500 microns, new refrigerant system works perfectly now H-350 L-150

My experience 2
Refrigerant 410a
H-350 L-125 high-pressure switch open. Faulty switch need to recover refrigerant replace high-pressure switch (one two red wires run to) and two filter/dryers. Leak test with 150-PSI nitrogen, Vacuum down to 500 microns. Recharge

3 Flashes low pressure/ loss of charge Blue & Brown wires to LP/LOC switch

Refrigerant charge lost due to leak

Most leaks will be found at the access fittings where we connect our gauges. I have found leaks at water condenser, Evaporator, and on copper line where they had rubbed against each other until it created a hole. If 0 pressure leak search with 150 Lb nitrogen repair leak vacuum all moisture out of system to 500 microns, recharge by weighing in refrigerant.

When arriving at a system you find it has 0 PSI Refrigerant pressure most likely the leak will be located on the liquid or discharge side of the system. Climate Master leaks are very hard to find in the past I have found them on the evaporator. Pressure tests may seem to hold due to the small leak, But if 0 PSI then you do have a leak. Look for oil stains anywhere on piping pressure test, refrigerant leak detector until you find the leak.

4 flashes Water coil low temperature limit grey wires to FP1 sensor

Cooling mode reduced or no water flows to water condenser.
Bad thermistor click here to see Temp/Ohm chart and compare. Temp/Ohm chart on page 11
Faulty TXV bulb loss of charge or plug/stuck valve
My experience Refrigerant 410a
cooling H-600 PSI L-50 PSI and dropping frost between TXV and air coil, trip on high pressure Heating H-350 PSI L-75 PSI cold between TXV and water condenser, trip on water coil low temperature
Found TXV stuck closed I replaced both filter/dryers, TXV, vacuum to 500 microns, new refrigerant system works perfectly now H-350 L-150

5 Flashes Air coil low temperature limit Violet wires to FP2 sensor

low refrigerant charge
faulty TXV
cooling mode reduced or no air flow.
Bad thermistor click here to check Temp/Ohm chart and compare. Temp/Ohm chart in page 11
My experience

Blower motor seized or low air flow

low refrigerant Refrigerant 410a high-240 low-55 superheat 77 subcooling 0
Found high service valve leaking – replace cores and caps. Recharge unit with 2lb 6 oz high- 320 low-120 superheat 9 subcooling 10

6 Flashes Condensate fault Yellow wire to condensate sensor

Blocked drain.
Always have Trap installed next to heat pump.
7 Flashes over/under voltage

Compare main power supply voltage and 24VAC before and during operation.
Thank you for visiting my blog I would appreciate any feedback I can get, Please leave a comment on whether my information has helped you. I am always interested in more topics to write so feel free to leave a comment asking about anything related to HVAC-R (Heating, Ventilation, air conditioning, refrigeration).

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