Automotive AC Repairing and Replacing – Replacing the Block-Style Thermal Expansion Valve

Replacing the block-style thermal expansion valve is much less invasive and does not require the removal of the duct box assembly. Below are the steps for replacing the block-style thermal expansion valve.

1. After recovering the refrigerant or verifying that the AC system is empty, remove the bolts that hold the line assembly to the valve.

After picking the correct Torx socket size, the fasteners for the thermal expansion valve can be removed by turning the ratchet

2. Remove the bolts that hold the valve to the evaporator core. These bolts are often very tight and can sometimes be seized, so lots of patience is needed to prevent a broken bolt. If the bolt seems to be seized, use a heat gun or small propane-powered heater to apply direct heat to the bolt to aid in the removal process.

The fasteners for the thermal expansion valve are often very tight, so extra care should be taken when removing them. It is advisable to firmly push the Torx socket into the fastener to cause it to grab the sides very

3. Remove the valve and match up with the new one TM to make sure you have the correct part.

Once the fasteners have been loosened with the Torx socket and ratchet, they can be removed by hand. The fasteners should be stored in a safe place to prevent them falling into a place that is hard to get

The thermal expansion valve is separated from the evaporator core by gently prying it away from the housing and pulling by hand. Sometimes it may be necessary to use a flat screwdriver to press against the valve to get it loose from the mounting

4. Install new gaskets or O-rings to the new valve and then install it back onto the vehicle.

The O-rings should be removed and replaced each time an AC component is serviced. A pick or similar tool is typically used to get under the O-ring to aid in the

The new O-ring should be carefully installed on the evaporator core inlet line. These O-rings can be installed by hand, but they should be closely inspected to make sure that it is not cut or damaged during installation. The O-rings should be lubricated with refrigerant oil prior to installing the new

5. Tighten all bolts to the correct torque using a torque wrench.

After installing the new thermal expansion valve into place, the fasteners are installed by hand. The last step of tightening the fasteners requires using a torque wrench, which helps attain the proper tightness of the fasteners. Correct torque on the fasteners ensures a quality repair that is not likely to leak or damage the

6. The AC system can be evacuated and recharged before being returned to service.

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