Finding Slow A/C Leaks

[Scamper]

Short version:

Had lost refrigerant a while back. Refilled, but that too was lost over several weeks. Added some dye and peaked around, saw nothing. Still leaked.

Pulled cooling unit and lo and behold, there was dye all around in there. Replaced evaporator and expansion valve.

Pulled a vacuum for 48 hrs to dry well before refilling, and decided to see how well it held a vacuum...it didn't. Over about 5 minutes it lost the vacuum almost completely. Fortunately, I didn't pump $50 worth of freon in it.

So I'm now wondering what else could be leaking, and can only come up with these possibilities:

-Condensor
-Receiver/Dryer
-Plumbing
-Low Pressure Switch

Any suggestions on how to find out where the culprit is? Or is it just easier to replace the condensor and receiver/dryer and be done with it, assuming that leaks in the plumbing and/or switch are unlikely at this point. Anyone else done this dance before?

 

[Rich]

You can fill it with non refridgerent gas with dye and look for more leaks. My guess is many shops would improperly use the normal refridgerent with dye and do same.

 

[Tools R Us]

That a big leak for an A/C system, a slow leak in the A/C world looses it's charge in months. I made an adapter to hook an air line to the fill line on my gauge set. For a big leak like this I fill the system full of air and look for the leak with soapy water from a spray bottle. You want a very foamy soap like dish soap.

 

[cabron]

Make sure to have a good light on it, these leaks can be very hard to see, even w/ soapy water.

 

[tucker74]

Hmm - this is interesting as I've got the same time of leak on my '94. I found dye around the drain at the firewall and assumed evaporator .... was going to replace that and the expansion valve and dryer (cdan mentioned you should always repace this too). If is was the condensor you would see something at the crossmember for sure - have you blacklighted all the exposed plumbing?

Tucker

 

[FJ809496TLC]

Pay attention to the refrigerant line connections. Pressurize line with dry nitrogen not air below the low side max pressure, use bubbles solution or if you have an electronic leak detector(best to use on small leaks), put trace of refrigerant in to the system mix with dry nitrogen. Be sure to vacuum system completely before recharging it.

 

[Scamper]

Tucker - The leakage around the condensate drain tube is undoubtedly your evaporater and/or expansion valve.

I have used a UV light to look for leaks everywhere I could get to, but with an installed system, this can be quite limited. For example, I'm not really able to see anything of the rear side of the condensor, and only limited amounts of the forward side. Likewise, the receiver/dryer is well tucked in there and not entirely visible without disassembly. So I'm not able to see or get at everything. For the same reason, I wonder about using a soapy solution with a pressurized system...

At present, I'm leaning toward just replacing the condensor and receiver/dryer, but would rather replace a problem part rather take the brute force and ignorant approach

 

[FJ809496TLC]

If you can access the evaporator housing and make a hole big enough for the tip of the electronic leak detector to get in, it should be able to detect it if there's a leak in that area. It can detect leak as small as an ounce of refrigerant per year.

 

[Tools R Us]

If you can access the evaporator housing and make a hole big enough for the tip of the electronic leak detector to get in, it should be able to detect it if there's a leak in that area. It can detect leak as small as an ounce of refrigerant per year.

They will sometimes detect it from the drain tube.

 

[FJ809496TLC]

They will sometimes detect it from the drain tube.

I agree.