Winter comes, teach you to easily cope with 10 symptoms and causes of abnormal frosting of air source heat pumps!
Frosting and defrosting of air source heat pumps is a normal phenomenon. The unit has an automatic frost function to ensure normal heating and hot water for users. In the current mainstream defrosting method, there is no need to stop the compressor or switch the four-way valve during the entire defrosting process. The indoor unit does not blow cold air, and has little effect on the temperature of the indoor side, and the comfort is very good. Users can rest assured!However, there are also some conditions that cause abnormal frosting of the unit, which is the main reason for the malfunction of the air source heat pump. The abnormal frosting and icing of the unit are only the superficial symptoms of the unit's "failure". The frosting symptoms are different, the pathology is different, and the cause is different, and the shape and form of the frost are different.
Frosting symptom 1: icing on the bottom
Cause: The water flow in the water pan is not smooth, and the icing spreads to the evaporator. Solution: Deicing, cleaning the dirt, and the water outlet is unblocked.
Frosting symptom 2: Partial icing of the evaporator
Reason: There is no frost at the defrost sensor, and the defrost point is incorrect. Solution: Manually forced defrost, move the defrost sensor to the icy/frosted place
Frosting symptom 3: The evaporator is full of frost/ice and does not defrost
Reason 1: Defrost sensor and ambient temperature sensor fault solution: manual forced defrost, resistance drift, replacement of the sensor. Reason 2: lack of fluorine or system blockage solution 2: add fluorine according to the standard, and remove the blockage by welding. Reason 3: The defrosting and four-way reversing valve does not change direction; the solenoid valve of the bypass defrosting system does not work. Solution 3: Check whether the valve is energized; check whether the valve works normally
Frosting symptom 4: Defrosting is not clean and incomplete
Reason 1: The temperature setting of the exit defrosting coil is too low, causing the defrosting to exit before the frost is completely cleared. Solution 1: Adjust the defrost parameters, increase the exit defrost temperature, and observe that it can be completely defrosted. Reason 2: The position of the defrost coil probe is inappropriate, not in the place where the frost is the most serious. Solution 2: Adjust the position of the defrost probe and place it in the most severely frosted place.
Frosting symptom 5: frequent frosting in a short time
Reason 1: The fin heat exchanger is dirty or blocked by foreign objects. Solution 1: Clean the heat exchanger or remove foreign objects. Reason 2: The fan motor is damaged or the fan air volume configuration is too small. Solution 2: Repair and replace the motor or replace the fan with a larger air volume. Reason 3: The refrigerant charge is too small. Solution 3: Add refrigerant to proper pressure. Reason 4: Throttle expansion valve opening is too small. Solution 4: Increase the opening of the expansion valve. Reason 5: The area of the fin heat exchanger is too small. Solution 5: Require the manufacturer to replace the fin heat exchanger and increase the area.
Frosting symptom 6: The frosting is very serious, and the fins are all covered with thick frost layer
Reason 1: The temperature setting of the entering defrosting coil is too low, or the defrosting time interval is set too long, which makes it impossible to enter the defrosting action in time. Solution 1: Adjust the defrosting parameters, increase the defrosting temperature, shorten the interval, and observe that it can enter the defrosting action in time. Reason 2: The position of the defrost coil probe is inappropriate, not in the place where the frost is the most serious. Solution 2: Adjust the position of the defrost probe and place it in the most severely frosted place.
Frosting symptom 7: uneven frosting, thick frost on some parts, no frost on parts
Reason 1: The refrigerant flow is uneven, some pipelines have large flow, and some pipelines have small flow. Solution 1: The manufacturer is required to adjust the structure of the refrigerant distributor to match the flow rate with the evaporation capacity. Reason 2: The structural design is unreasonable. For example, the upper and lower height of the fin heat exchanger is too high, resulting in an excessive difference between the upper and lower face wind speeds. Solution 2: Require manufacturers not to make the height of the heat exchanger too high, or increase the air volume of the fan.
Frosting symptom 8: low pressure protection during defrosting
Reason 1: There is no delay in low pressure detection during defrosting or the delay time is too short. Solution 1: The low-pressure protection in the defrosting process needs to be delayed or extended. Reason 2: The throttle expansion valve is blocked or the opening is too small when it is reversed. Solution 2: Replace the expansion valve or increase the opening of the expansion valve.
Frosting symptom 9: high pressure protection during defrosting
Reason: The temperature of the exit defrosting coil is set too high, resulting in the high pressure protection still not exiting the defrosting. Solution: Adjust the defrost parameters, lower the exit defrost temperature, and observe that it can be completely defrosted.
Frosting symptom 10: the fins have defrosting without frosting
Reason: The temperature (or temperature difference) of the entering defrosting coil is set too high, causing malfunction. Solution: Adjust the defrosting parameters, increase the entering defrosting temperature (or temperature difference), and observe that the fins are frosted to an appropriate level before defrosting.
