Air conditioning valves on a vehicle can expand if necessary to allow more coolant to get to the evaporator. The valve can also retract to enable less coolant flow into the valve if it is not necessary. There is a sensor that controls the coolant flow in a vehicle. After many years of continued use, the A/C valve may malfunction and will need to change out faulty part with a new one. The process to do this task could vary slightly depending on the vehicle, but is generally the same.
Loosen the connections to the lines that run to the evaporator with an open-end wrench. This could take a little muscle if the connections are rusty.
Take out the screws that attach the bottom section of the evaporator with the appropriate type screwdriver. Remove the water drain tube with the open-end wrench.
Use the wrench to remove the airbag harness and feed it through the hole. Once the airbag is detached, loosen and remove the bolts that secure the bottom part of the evaporator. Lift up and remove the evaporator from the vehicle.
Remove the clips and screws that close the evaporator. Once the screws are free, lift open the evaporator so you can see the valve. Twist the valve with a wrench until it is free.
Apply an engine lubricant to the O-ring so you can install the new valve. Push the new valve into place and twist it counter-clockwise with a wrench so it does not move.
Reinstall the airbag and evaporator in the same manner that you removed them. Check the air conditioner to make sure it has remedied the problem. If it has not, you may want to have the vehicle inspected by a qualified mechanic. It may be a good idea to take the vehicle to a mechanic for an estimate before attempted work on it.
Necessary Materials
Screwdriver
Wrench
Lubricant