Rick's Free Auto Repair Advice

Fix an air conditioning leak

How to Fix an air conditioning leak

If your AC cools the air slightly but it’s not as cold as it used to be, chances are its low on refrigerant. Most AC leaks are caused by deteriorating “O” ring seals. Every joint in the system has at least one O-ring seal. These O-rings are specially designed to be compatible with refrigerant and A/C oil. You MUST replace them with the specific type of O-ring for your vehicle. You cannot use black plumbing style O-rings.
To disassemble a joint, you first have to have the system evacuated and have the refrigerant recycled. Once the system is empty, you’ll most likely need a special disassembly tool. And if the joint doesn’t pull apart, use a heat gun to warm the components. Do not get them hot, just warm.
Replace the O-ring with new parts and coat the new rings with the specific refrigerant oil recommended by the manufacturer. Then reassemble the joint.
Refrigerant can also leak from the compressor main seal. This seal is unlike any other type of automotive seal. It has two hard carbon faces that ride against each other under spring pressure. Running the A/C when it’s low on oil can damage the carbon faces and wear them, causing them to leak. A/C sealer will not seal this type of leak. Nor will A/C sealer stop a leak in an O-ring or a rubber hose. In fact, if you ever plan to take your car to a shop for professional A/C repair, you should avoid A/C sealers completely.
A/C sealer stays a liquid when inside the system and hardens when it’s exposed to air and moisture. So it hardens at pin-hole leaks (theoretically). But O-rings and rubber hoses flex which changes in temperature and that flexing breaks the temporary seal. That’s why it doesn’t work on soft parts. It’ll only work on leaks in metal tubing, the condenser, or the evaporator. But heed this warning about A/C leak stop products; once you add them to the system, your system is contaminated. A/C leak stop products damage professional refrigerant recycling machines. And don’t think you can hide the stuff from a pro. They test your refrigerant before they attempt an evacuation. If they find any trace of stop leak, they have to empty your system using a special container and send the refrigerant off for special recycling. And that’s gonna cost you about $200. So don’t use this stuff unless you know for sure you’ve got a leak in a metallic component. And don’t use it if you think you’ll wind up at a shop anyway.


© 2012 Rick Muscoplat

Posted on by Rick Muscoplat

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