Slow AC leak, 06 LGT

[SweetJustice]

TLDR: Replaced both coils. No bubbles anywhere. System still leaks down to not working in 3-4 weeks.

 

History as follows:

 

1. Local Subaru dealer diagnoses a leaky condenser coil, quotes $1400 to replace it. No thank you m'am! Bought an aftermarket unit off ebay for $80 and charged it with Redtek.

 

1b. 4 weeks later, no cooling.

 

2. Bought a UV light, figuring maybe the previous owner ran dye through it, or maybe I will. Pretty much the entire engine compartment fluoresces. Oh well.

 

3. Bought a fleabay halogen detector. It alarms on the floorboards. A-ha! Another $80 on ebay for a new evaporator coil, and I'm golden, right? It held 100psi overnight, anyhow.

 

3b. See 1b, above. 50psi static, 80/25 running. No cold.

 

4. Deep research into bubbles. Consensus appears to be: 250 mL distilled water, 25 mL Dawn (not Ultra!), 5 mL glycerin. Can confirm, it works very well in a bubble wand.

 

4b. Spray bottle time. Nothing. Sprayed the bejesus out of the compressor, as much of the condenser and its joints as I could reach, I even took the dashboard apart (*again!*) to spray the evaporator joint. Did the entire lengths of both high and low lines in the engine compartment. In desperation, I even sprayed the service ports. Nothing. Not a single bubble.

 

Advice welcomed! Do I just keep replacing components one by one until I figure it out? Should I do the lines next or the compressor?

[Max Capacity]

Most any local repair shop will be able to put a die in the system and look for the leak. Don't pay the dealership to repair your 11y/o car. call around to the car repair shops and ask them

[08SpecB_DE]

Did you replace all of the o-rings? Did you pull a vacuum after you cracked the system open? If you're in my area, you can borrow my gauges. I have an oil filler in-line on the low side so you can put some uv dye/oil in the system as well.

[cseagle08]

did you check for leaks while the system was running? Maybe the heating/cooling of the various lines is causing a crack to open and leak?

[SweetJustice]

did you check for leaks while the system was running? Maybe the heating/cooling of the various lines is causing a crack to open and leak?

 

Pulled down to about 400 microns, but it wouldn't hold below about 600-700. AFAIK, anything holding below 1000 means there's no more moisture, so I didn't worry about it. I chalked it up to old oil in the pump -- vacuum pump oil is hygroscopic.

 

It didn't occur to me to replace the o-rings though. I don't see a spec for them in the service guide. Do I just have to buy the o-ring kits from the dealer?

[SweetJustice]

did you check for leaks while the system was running? Maybe the heating/cooling of the various lines is causing a crack to open and leak?

 

Sadly, I didn't, at least not while fully pressurized. I did after it had leaked down to 80/20 psi, and didn't see any bubbles, and didn't get any action from my leak detector.

 

It's a good idea, I'll do it after I replace the o-rings.

[SweetJustice]

So I took my $75 to the dealer for a new set of O-rings. Took the whole damned thing apart again, replaced the O-rings, pulled a good vacuum for two days, and recharged...lasted a week before it was dead again.

[SweetJustice]

The story does have a happy ending, though: after tearing the last little bit of my hair out, I took the car to a shop downtown that has a reputation for being good with AC problems.

 

They washed out the engine compartment, did a dye charge, and found a leak at one of the condenser O-rings. He thought it was possible that I "rolled" one of the o-rings when replacing it, it's apparently something that just happens sometimes.

 

Anyhow, they replaced the o-ring (no charge, they apparently only cost about $0.07 each when you don't buy them from the dealer), and it's been good for six months now.