How to Replace an Air Conditioner Valve

What You'll Need
Wrenches (variables sizes depending on car, and screw sizes)

The car's air conditioner valve provides the variation in the coolant flow depending on the cooling demand. The more cool air that is needed, the valve opens wider to allow more coolant to go in to the evaporator. Once a sufficient amount of demand air is met, the valve opening closes to decrease the flow. A sensor bulb is mounted near the evaporator to monitor the cooling demand.  

If the air conditioning system is not functioning properly, it is a good chance that you may need to replace the valve. If you are doing any other major service to the air conditioning system, it is always good to replace the valve as well. It can get clogged with a lot of debris from the system.  When debris restricts the coolant flow, the oil that flows through the air conditioning system is also restricted. Although replacing the air conditioning valve is not expensive, not replacing it can cause a lot of issues with the air conditioning system and end up costing hundreds of dollars.

Step 1Unhook the Air Conditioning Lines

Unhook the air conditioning lines that go into the evaporator. 

Step 2 – Remove the Glove Box

Take the screws out and unhook it from the plastic latch. Removing the glove box will expose the evaporator.

Step 3Remove the Bold

Remove the bold that holds the low part of the evaporator. Next, loosen the water drain tube beside the bold.

Step 4Remove the Airbag

After making sure the battery is not plugged in, remove the airbag. Remove the remaining bolts. Unhook your airbag harness, pull airbag out by pushing the harness wiring up through the opening. Removing the airbag enables you to remove the bolt that holds the evaporator.

Step 5Remove the Evaporator

Next, remove the styrofoam casing that holds the evaporator.

Step 6 – Open the Evaporator

Remove the screws and clips, and open the evaporator. This should display the valve. You may clean the evaporator at this time also.

Step 7Remove the Valve 

This will require a couple of wrenches. Replacement valve may have what they call an “O ring.” You may apply lubricant to the O ring. It is never a good idea to reuse an O ring.

Step 8 - Reinstall the Valve

Reverse the order of the steps mentioned above. Once the evaporator is ready to be installed back in place, adjust the rubber seal on the engine bay before you tighten it up in place. 

Air conditioner valve is best serviced by replacement. Since these valves are low cost to buy, it is generally easier to replace these valves as opposed to cleaning them to ensure they are free of all debris. If the valves are not replaced, you can ultimately end up having to replace the whole compressor. Some expansion valves have an external thermometer or sensor referred to as capillary tubes. This external part of the valve is also exposed to damage.