If your air conditioner keeps icing over, the problem might be a bad thermal expansion valve. This valve is part of the refrigeration system in your air conditioner, and when it malfunctions, your AC won't be able to cool your house very well.
Your air conditioner might run all day and not cool your house, or it might freeze over and shut down. Here's a look at the important role the expansion valve plays in cooling your house and what an AC repair technician might do when the valve goes bad.
The Expansion Valve Cools The Refrigerant
The refrigerant in your air conditioner is always in circulation when the AC runs. However, during the cycle from the condenser coils to the evaporator coils and back, the refrigerant changes from a gas to a liquid and then back to a gas.
In order for the refrigerant to get cool enough to turn to a liquid and pull heat from your home, the system needs help from the expansion valve. The expansion valve reduces pressure on the refrigerant so it cools down fast as it circulates back inside your home through the evaporator coils.
A Faulty Valve Can Sometimes Be Repaired
An expansion valve can go bad due to age and wear and tear, but other times, the problem is moisture or debris in the line. When moisture gets in the valve, it can freeze due to the low temperatures, and the ice can block the valve and cause it to malfunction. The AC repair technician may want to solve the cause of freezing so it doesn't happen again with a new valve.
They might do this by adding a filter to control moisture and to keep out other debris that might get caught in the valve and cause it to malfunction. When debris and moisture are the cause of your air conditioning problem, the AC repair technician might clean and dry the valve rather than replace it.
A Bad Thermal Expansion Valve Can Be Replaced
When your AC malfunctions by icing over or failing to keep your home cool, the repair technician has to troubleshoot the issue since several things can cause the problem. If the expansion valve is identified as being bad, the repair technician can remove the valve and put in a new one. Switching the valve is a fairly quick and easy job, but that is only part of the process. The refrigerant has to be removed and refilled too.
Since the valve is part of the refrigerant circulation system, the refrigerant has to be drained to remove the valve. Once the valve is replaced, the refrigerant is filled and the temperature and pressure have to be brought to the proper range by adjusting the new expansion valve.