2002 suburban 3.5

 

Refrigerant leak detection can be tricky. Typically a combination of visual observation, UV dye/UV light & goggles, electronic sniffer, even soap bubbles. If you have rear AC, then more places to leak.

In other words, I recommend having a real AC shop diagnose the leak (specify that); then you can determine if you have the skills and equipment to repair it yourself.

 

the only thing a diyer can do is charge the system and spray dishsoap/water solution on all the parts...hopefully, the leak is big enough to detect bubbles.

 

I myself also have UV light & goggles and an electronic sniff tool.

 

I have a mechanic that does any work that I am unable to do myself on my '01, and without the tools, leaky AC is one of them. Yet despite the fact that he does so much of this work, he struggled to locate the leak on my vehicle. It ended up being on the valve on the high pressure side, but with a leak so slow that I'd be well into winter season before it would drain the system.

 

You mean the high side service valve? The cap really does the real part of the seal there.

Or do you mean the rear expansion valve (for the rear AC) ??? That's tough to access.

 

The Schrader valve, not the cap, is what maintains the pressure in the A/C system. Saying the cap does it is like saying the plastic cap on your valve stems is what holds the pressure in your tires.

 

Most service valves leak a little. The AC experts on the dedicated AC forums say the cap is essential to help make a good seal. If you're an AC expert yourself, you may dispute and/or argue directly with them on their forums.

And most AC shraeder type valves are replaceable, and many can be switched out without losing refrigerant using the correct special tool. I haven't done this, but the experts say this, and I've seen such tools.


That's why I use metal tire valve caps on vehicle tires and my bicycle tires; they have with a good rubber seal inside them and seal way better than the plastic dust caps..

 

Not an AC expert by any means but I'm pretty sure that those dinky little plastic caps on the R134a systems will not withstand 300 PSI. The nice metal caps with o-ring seals on R12 systems may prevent a leaky Schrader valve from leaking.

 

My 2007 Tahoe had a leak at the low side charge port, the schrader valve must have gotten debris in it when I checked the charge. I was going to replace the valve BUT the 07's do not have a replaceable one WITHOUT evacuating the system.
I ended up putting some PAG oil in the valve and attaching the gauge set and I guess that allowed what ever was holding it open to get displaced as it has done fine since. This is probably a case of leave well enough alone, if it ain't broke don't fix it.. (I thought I was being pro-active by checking it, turns out I created the problem that didn't previously exists)