Isn’t it amazing that the problem itself shows a sign that helps you to fix it? No kidding. Frosting direction can indicate possible causes if your transport refrigeration unit has such a problem. Follow Corunclima to figure out how to cope with it.

If the frosting starts from the compressor return air inlet to the evaporator, possible causes are:

1. The throttle valve opens too large. The appearance is the temperature and pressure of the return condensate are normal or slightly higher, and the frosting is gradually formed from the compressor return air inlet to the evaporator.

2. The evaporator cannot absorb heat normally, or the cold energy produced by the evaporator cannot be taken away. The appearance is the temperature and pressure of the return condensate are normal or slightly lower, and the frosting is gradually formed from the compressor return air inlet to the evaporator. After a long time, ice is formed from the compressor return air inlet to the evaporator and from the throttle valve to the evaporator, and the low pressure occurs at the end.

The troubleshooting measures are: check if the air filter is clean; check if the blower/fan spins normally; check if the evaporator is clean; check if there is a blockage in the air supply system; check if the belt is too loose.

If the frosting starts from the expansion valve to the evaporator, possible causes are:

1. The refrigerant is less (leaking). The appearance is that the temperature of the return condensate is slight higher but the pressure is not, and the frosting is gradually formed from the throttle valve to the evaporator.

2. The expansion valve opens too small. The appearance is the temperature and pressure of the return condensate are normal or slightly lower, and the frosting is gradually formed from the expansion valve to the evaporator.

3. Check the visual liquid mirror and the condition of the refrigerant. If the bubbling is fierce, it could be the system leakage; if the bubbling is none or few, the expansion valve maybe opens too small, or there is a blockage, generally there will be large temperature difference before and after the blockage.

Together with Corunclima, let’s enjoy the comfort brought by worry-free transport refrigeration unit and air-conditioning system for trucks, vans, and various types of vehicles!