8 Causes Of Air-Source Heat Pump Failure



8 Causes Of Air Source Heat Pump Failure

January 12, 2024

1. Analysis of current fault causes:

A. Confirm the detection accuracy of the current transformer and confirm the adjustment of the thermal relay protection value.

B. The voltage is too low or too high, causing the compressor current to be too large.

C. The compressor wiring, AC contactor, and power terminal wiring are loose.

D. Insufficient water flow leads to excessive compressor load, which can also cause current failures.

E. The refrigerant system fails, causing damage to the compressor itself and causing compressor current protection.

2. Causes of exhaust probe failure:

A. Too little or too much refrigerant in the system will cause the exhaust temperature to be too high.

B. The system refrigerant is impure (refrigerant quality) causing the exhaust temperature to be too high.

C. The exhaust probe circuit is damaged or the resistance value of the temperature sensor head drifts, causing exhaust failure.

D. The heat pump throttling device (electronic expansion valve) is slightly blocked or the throttling device is incorrectly adjusted due to other reasons, resulting in excessive exhaust pressure and high exhaust temperature.


3. Causes of high voltage failure:

The high voltage protection of the unit operation panel is often caused by many reasons, and it is often troublesome to find the problem quickly and accurately. The causes of general high-voltage faults are as follows:

A. If a heat pump has been repaired, check whether there is too much refrigerant. It will not show up when the temperature is low in winter. In summer, it will cause excessive pressure and cause high-pressure protection.

B. The head and flow rate of the circulating water pump are too small and are not equipped according to the company's requirements (check the temperature difference between the inlet and outlet water during normal startup and operation of the unit. A temperature difference of 5-7 degrees is a reasonable range. A temperature difference exceeding 7 degrees means that the waterway is blocked or the water pump selection does not match).

C. The unit reports high voltage when it is turned on, which can detect whether the high-voltage switch circuit is damaged or the high-voltage switch body is damaged and cannot be reset.

D. Hot water unit: Whether the low water level probe of the water level probe is properly installed and the probe should be higher than the circulating water inlet; Cooling and heating unit: Make sure that the inlet and outlet water probes are placed reasonably and the temperature sensing is accurate to avoid inconsistency between the sensing temperature and the actual temperature (the probe is damaged or the temperature sensing temperature position is wrong), resulting in high voltage protection of the unit.

E. There is a scale in the condenser (casing, high-efficiency irrigation, plate heat exchanger), resulting in poor heat exchange and high pressure in the system. The use of groundwater generally causes this.

F. When the tap water is stopped, poor detection of the water pressure switch will also cause a high-pressure alarm (with automatic water replenishment and high-pressure protection).

4. The unit is not running:

There are several possibilities for this situation, which need to be investigated step by step. The specific troubleshooting steps are as follows:

A. Power failure, turn off the power switch and check the power supply.

B. The power wiring of the unit is loose. Find out the cause and repair it.

C. The unit control power supply fuse is blown, replace it with a new one.

D. Hot water unit: Check the high, medium, and low water levels. If the unit cannot detect the water level, it will not start;

Heating and cooling unit: Check the linkage and common terminals. If the linkage and common terminals are not connected, the unit will not start;

Installing the unit at low ambient temperature: The unit has a preheating function (the compressor icon flashes), but the unit will not start if the preheating time is insufficient.

5. The water pump is running but the water does not circulate or the water pump makes a loud noise:

On the premise that there is no problem with the waterway system if the water pump is running but the water does not circulate or the water pump makes a loud noise, there are various reasons. Common ones include lack of water in the waterway, air, etc. Therefore, we need to clarify the idea and troubleshoot the reason why the compressor does not start step by step:

A. There is a lack of water in the water system. Check the system water replenishment device and replenish water in the system.

B. There is air in the water system. Remove the air in the water system.

C. If all the water system valves are not opened, please open the water system valves fully.

D. The water filter is dirty and clogged. Clean the water filter.

E. The water pump itself is damaged and the impeller slips. Check the actual operating current of the water pump (in normal operation, the current is lower than the normal value).

6. The heating capacity of the unit is low:

A. There is insufficient refrigerant. Check the system for leaks and refill the system with refrigerant.

B. The water system is poorly insulated. Strengthen the water system insulation.

C. The filter dryer is clogged, replace the filter dryer.

D. The air heat exchanger has poor heat dissipation. Clean the air heat exchanger.

E. The water flow is insufficient, clean the water filter.

F. Check whether the fins of the unit's surface cooler are dirty or blocked.

G. The ventilation effect of the outdoor unit is not good, or the fan is not operating properly.


7. The compressor is not running:

A. Power failure, find out the cause and solve the power failure.

B. Secondly, check whether the compressor contactor is damaged and replace the contactor.

C. Check for loose wiring, identify loose points and repair them.

D. Sometimes it is the compressor overheating protection. Find out the cause of the heat and eliminate the fault before turning it on.

E. If the outlet water temperature is too high, the compressor will not operate. Reset the outlet water temperature.

F. The water flow is insufficient. Clean the water filter to eliminate the air in the system.

8. The compressor operates with loud noise:

A. The compressor only compresses gas but not liquid. Liquid refrigerant enters the compressor. Check whether the expansion valve has failed.

B. The compressor refrigeration oil is insufficient or the oil return is poor. Add an appropriate amount of refrigeration oil and check whether there is any blockage in the refrigerant system.

C. The internal parts of the compressor are damaged, replace the compressor.


+86 182-5318-3976

+86 182-5318-3976

+86 182-5318-3976


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