Automotive AC Repairing and Replacing – Replacing AC Schrader Valves

Use the following steps when servicing Schrader-style valves.

1. Remove the plastic service cap to determine which check valve style is used.

The service ports have plastic caps that need to stay in place except when service needs to take place. These caps prevent dust and debris from entering the service port in addition to serving as a secondary seal device for refrigerant leaks. Close attention should be used when removing the caps to see if any pressure releases when the cap is removed. If pressure is present when the cap is removed, then the check valve is leaking and will need to be

2. Choose the correct tool to remove the Schrader valve.

The tools needed to remove and reinstall Schrader valves are available at tool suppliers and parts stores. There are several sizes of valves, so it is important to use the correct size tool when servicing the

3. Install the correct tool into the valve and turn counterclockwise to remove the valve.

The Schrader valve service tool is inserted into the service port and lines up with the top of the assembly to allow for removal. This process can only be performed after the system has been safely recovered. Do not remove the Schrader valve when the system is charged with refrigerant because it will quickly vent out when the valve is

The socket-style tool is needed for the larger size Schrader valves. These valves are easily removed with light pressure on the ratchet. This process should be performed after the system has been safely recovered. If you remove the Schrader valve with the system charged with refrigerant, it will quickly vent to the atmosphere when the valve is

4. Match up the original valve with a replacement valve.
5. Set the new valve back into the opening and use the tool to turn the valve clockwise, being very careful to align the threads perfectly and prevent damage to the threads because of misalignment.

The Schrader valve is carefully inserted into the service port by hand. After setting the valve into the port, the tool is needed to carefully turn the valve clockwise to engage the threads. The ratchet is used to finish the tightening procedure, using care to not overtighten the

6. Tighten the connection to the correct tightness by using mild hand pressure. Use an in-lbs torque wrench if one is available to tighten to the exact specification. The torque value on the valve depends on the diameter of the unit. The range of torque is 3 to 6 in-lbs on the smallest-size valves up to 15 to 30 in-lbs for the largest-size valves. The specification for this torque can be found in a reliable source, such as a service manual or on an electronic database.

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