A/C o-ring kit (1 Viewer)

[tonkota]

I bought an o-ring kit to replace all the o-rings in my A/C system. The good news is that I just used the Harbor Freight vacuum pump to suck the system down to 25 inches. It's been holding now for a few hours. I'll leave it overnight and see where I am at tomorrow.

Now for the question:

Where do all of these o-rings go? I can count 8 places and there are more than 8 o-rings. Not all of them are round ones. Is there a diagram? The FSM doesn't seem to show where they go either.

 

[TX Cruiser]

You'll figure it out when you separate the lines. They send extras, ones you'll never need. Take the expansion valve for instance. If I were you, I'd do the opposite of a vacuum and find the leaks with a bottle of soapy water.

25 in hg is alright, but the more important thing is the pressure the system can hold, not the vacuum. The reason I say this is because the vacuum can suck the o-rings back in and leak under pressure when they get pushed back out. Change your schrader valves regardless.

The square ones pretty much have to be for the compressor manifold plates, but that's only two of them.

 

[tonkota]

How can a home mechanic pressurize the system? I don't want to waste refrigerant and I was told never to use compressed air.

I don't think I'll open the compressor to replace those o-rings.

Thanks for the tips!

 

[TX Cruiser]

The introduction of nitrogen into the system is the preferred method, but those that say compressed air is bad are probably the ones that don't vacuum the system down to boil the moisture out.

Hook the gauges up, remove the yellow hose from the gauge manifold, use your rubber tipped nozzle attached to your air compressor and place it where the yellow hose was, then open the valves on the gauge manifold, blow air into the system and bring the pressure up to 120-150 psi, then close the valves. Once you have pressure in the system, take a spray bottle filled with soapy water and spray away at every hose, line, fitting (remove the gauges to check the schrader valves too) condenser, compressor manifold, etc... Where you find bubbles, you have a leak.

EDIT: If your compressor has a bad habit of moving condensate from inside the tank down the line, I wouldn't use compressed air.

 

[Elbert]

I don't think the introduction of compressed air is the normal route to finding freon leaks? It may work...fine.
Standard test is to pull vaccum down in the 20's ....let vaccum pump for a hour or so...turn pump off, close valves and see if system holds the vaccum for an extended period. I don't think there's a whole lot of issues with vaccum damaging or altering the seal at teh "o" rings. This has been the standard procedure for 40+years... Generally you may also introduce some freon with a specali oil that has dye in it...you then use the black light to check for leaks. The vaccum method works very well without special tools.

 

[TX Cruiser]

Not always. I'd be willing to bet more a/c shops find the leaks with compressed air than any other method. Sniffers for evaporator leaks probably runs a close 2nd. I never understood why people use dye, I guess they can't see the oil?

 

[Elbert]

the dye makes it easy to see with a black light. It is hard to find without the dye depending on the leak. In the old days it was a sniffer and then dye/black light time. Some of the sniffers are not that good. You run the sniffer around all hte captured "o-ring" connectons and obvious areas... Sometimes you're lucky and the leak is obvious...ruptured hose, other common area...are the o-rings ...and any seal type areas.

 

[tonkota]

Thanks for the thoughts. I was replacing some of the o-rings last night. I have run into trouble with the larger line where it meets at the fire wall. The nut broke free easy enough, but when I got about 3 threads loose it began to get very tight. I stopped to think about it and haven't done any more. Any ideas? I hope the AL didn't gall.