So, my truck's a/c stopped working rather quickly. It was working well and last weekend the compressor stopped coming on. I took a multi-meter to the relay, it was good, fuses were good and when the accumulator switch was jumpered it came on so I added freon. It blew nice and cold for a day or two and then back to square one!

I started looking around for the leak before I put the dyed refrigerant in. When I untwisted the high pressure line service cap some freon escaped and there was a little oil under it and on the line.


My question is this:
Could that be the leak? There wasn't much oil but I know there's not much in the system to begin with. I definitely heard the freon escape but I'm just wondering how often those little service port check valves go out and whether just a little oil is a good enough indicator before I replace the line.

 

Common leak point.

The valve should be able to be removed with a tool similar to the ones that remove the valves in tires.

When you change it, you'll need to draw vacuum on the system to remove any water. 30 minutes should do it. Then refill it with refrigerant that has oil in it, that type is typically meant for recharging systems that have suffered a leak, so it's premixed in the correct amount.

It might not be a bad idea to replace the accumulator/drier as well. That device helps remove moisture from the system and keeps it nice and cool.

There is another product I might suggest: its called red angel ac stop leak. Its really good in that it doesn't gunk up the filters in ac repair machines like the stop leak in a can that you see in the parts stores in the cheaper brands. It ain't cheap, but it works darn well. I've only ever seen it as a straight liquid you have to use a dye injector canister for, but I heard recently that they make it mixed in a can with refrigerant. If that is true, that would be the type I'd get. Much easier to put in.

If you use that stuff, you wont need the extra oil in the other cans, and you can buy just the straight r-134a.