There are a number of locations where refrigerant can leak from a central air conditioning service. However, one location that commonly leaks is the service valve; this problem is especially prominent in older systems. If you are losing refrigerant in your system, then you should perform a tune-up on your service valve. Below is more information about this vulnerable component as well as how you can fix the problem:
Service valves - what they do and why they leak
The service valve is used for the purpose of shutting-off the flow of refrigerant between the outside condensing unit and indoor coils. The service valve also contains a Schrader valve, similar to that used on an automobile tire, for the purpose of attaching testing and recharging equipment. To operate the valve, a protective cap is removed and a plunger is moved up or down by turning a hex key; the plunger either blocks or permits the flow of refrigerant depending upon its position inside the valve body.
The service valve is prone to leak around an o-ring that surrounds the plunger. This leaking occurs either due to natural deterioration of the o-ring over time, or it can also occur if the o-ring is damaged when the refrigerant lines are soldered to the valve. Regardless of cause, you can correct this problem by replacing the o-ring. Here is how it's done:
Tools and materials needed
Replacement o-ring for your valve
Clean shop towel
Plastic bristle brush
1. Ensure that all refrigerant is evacuated from your system - before performing any work on your service valve, it is crucial that your air conditioner be completely free of refrigerant. Proper evacuation requires that an EPA-certified technician remove the refrigerant so none of it escapes into the atmosphere.
2. Remove the service valve cap - after the refrigerant is properly evacuated from the system, you will need to access the service valve by removing the protective cap. This cap is designed to protect the service valve from tampering and debris, and it can be removed by unscrewing it with a pipe wrench. Be careful not to damage the threads when unscrewing the cap, and set it aside in a safe location.
3. Remove the retaining ring - once you remove the valve cap, you will see the plunger and a snap-ring that prevents the plunger from being removed from the valve body. Remove the ring with a pair of snap-ring pliers.
4. Unscrew the plunger - after the retaining ring is removed, the plunger is ready to be unscrewed from the valve body. Insert an appropriately-sized hex key into the plunger's key socket and turn the plunger counterclockwise until it completely unscrews from the body.
5. Remove the o-ring and clean the plunger - first, slip the o-ring off the plunger and discard it. Next, soak the plunger in a small container of mineral spirits to remove any leftover residue from the o-ring or other debris. Scrub the plunger with a plastic bristle brush if soaking isn't sufficient to remove all particles. Wipe the plunger with a damp shop towel soaked in mineral spirits and allow the plunger to dry completely. Once the plunger is clean and dry, slip a new o-ring over the plunger and position it in its groove.
6. Replace the plunger - after the plunger has been reconditioned, inspect the inside of the valve body for debris. Use a damp shop towel to wipe down the inside of the valve if you see any residue. Reinsert the plunger, and use a hex key to lower the plunger into the valve body.
After inserting the plunger, install a new snap ring with a pair of snap-ring pliers. Use the hex key to adjust the plunger so it flush against the snap ring; this is its position for normal operation.
7. Replace the valve cap - as soon as you have reinserted and adjusted the plunger, you can replace the valve cap by screwing it on to the valve body. Do not overtighten the valve cap or you may damage the valve threads.