Heat Pump Frost/Ice/Freeze Up: Why and What-to-do?


frozen heat pump2 300x232 Heat Pump Frost/Ice/Freeze Up: Why and What to do?

heat pump frost up in winter

First of all, it’s completely normal for the out-door unit of your air-water heat pump to be covered by frost or light ice during cold winters. Before it becoming too heavy, your heat pump will go into the defrost mode to remove the coating of frost or ice.

When the defrost function does not work accurately any more, your air-water heat pump could be frosted/iced/freeze up abnormally and can not defrost well. Your heat pump will lost its heating capacity. The performance, why and what-to-do for abnormal frosting/icing/freezing are listed below:

 

 

Performance
Why
What to do
out-door unit bottom iced upwater outlet of drip pan blocked. icing up.dredge drip pan
evaporator partly iced uplocation of defrost sensor not rightdefrost manually; move defrost sensor to the right place
evaporator covered by frost/ice, no defrosting1. defrost sensor error or ambient air temp sensor errordefrost manually; change sensor
2. lack of refrigerantadd refrigerant
3. 4-way reversing valve failed or electromagnetic valve failed check valve
defrost not completely1. quit-defrosting-coil-temp set too lowchange the parameter. set quit-defrosting temp higher
2. coil defrost sensor put at wrong place, where frosting not the most seriouslyput the sensor at the place where frosting is the most serious
frost up too frequently1. evaporator not cleanclean evaporator
2. fan motor broke or fan not powerful enoughrepair fan motor or change or change a bigger fan
3. refrigerant not enoughadd refrigerant
4. throttle expansion valve small openingmake the opening bigger
5. evaporator not big enoughchange a bigger evaporator
frost up badly, fins all covered by heavy frost1. start-defrosting-coil-temp set too low, or defrost interval time set too long. Can't start defrost in timechange parameters
2. location of defrost sensor not right, not where frost is the most seriousput the sensor at the place where frosting is the most serious
frost not evenly distributed. somewhere heavy, somewhere thick1. refrigerant not evenly distributedadjust refrigerant distributor. refrigerant flow should match evaporating capacity
2. structure of fin-coil evaporator not goodchange evaporator or use a bigger fan
low-pressure protect when defrosting1. defrosting low-pressure test not delayed not delayed not enoughdelay and delay for enough time
2. throttle expansion valve blocked or opening too smallchange the valve or make the opening bigger
high-pressure protect when defrostingquit-defrosting-coil-temp set too high. not quit defrosting when high-pressure protectingchange the parameter
start defrosting while no frost on evaporatorstart-defrosting-coil-temp set too highchange the parameter

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