97' Impreza Outback A/C Leak

[palfer]

So this is the 3rd time in the last 12 months my A/C has quit.  After reading on this forum I replaced the O-rings at the compressor and a few other areas for good measure as well as the dryer.  Repeated the O-ring change at the compressor about 4 months ago and am now back again. 

 

Each time the hooked up a pump and pulled vaccuum which held and then I filled with freon.  I bought a sniffer and will see if that can find a leak that I can't see with U/V light.  I was thinking that maybe my replacement green HBNR generic O-rings might be the culprit.

 

Should I try to order these from the dealer instead of matching sizes?  Thoughts?

 

Thanks!

[idosubaru]

i've matched sizes countless times without issues, that shouldn't be the issue.

 

steps:

1. verify it's low.

2. find the leak

 

if i'ts at an oring - then maybe you need to check that fitting.  the hoses are prone to leaking too - check the hoses.

[1 Lucky Texan]

could be a hole in the condenser, or leaky schrader valves  too.

Edited November 25, 2015 by 1 Lucky Texan

[Rooster2]

My recent experience, a refrigerant leak turned out to be a pin hole leak in the metal tubing that connects to the bottom of the condenser. You never know where a leak can begin. As already advised, do a thorough job of checking everywhere for leaks with the sniffer and U/V light. Both are very good tools to find leaks.

 

I have replaced black O rings with green O rings with no issues. So, I would not think that is a problem.

[Loyale 2.7 Turbo]

I've had always Good results with A/C stop Leak + Leak Detection fluid:

 

~► http://www.ebay.com/itm/A-C-Stop-Leak-R-134A-Leak-Sealer-A-C-Leak-Stop-Seal-with-Leak-Detection-Dye-/281589833580

 

The Leak Detection Dye makes the job, easier... Kind Regards.

[Fairtax4me]

Bottom corners or the condenser like to corrode and can cause very small leaks. Also have seen corrosion around the o-rings where the lines attach to the condenser.

 

Sounds like a bad o-ring or corrosion around an o-ring since it holds vaccum. They get sucked in when the vacuum is on them, then pushed out when the system is charged.

[palfer]

So I finally got back to this A/C leak.  When I hooked up the gauges there was no pressure in the system.  I hooked up my pump and pulled a vacuum to see if it would hold.  When I turned off the pump and closed the gauge valves I lost the vacuum in about 15 seconds and it returned to zero. 

 

My next step was to try to put a small amount of refrigerant into the system along with some dye just to get the compressor working and pushing Freon throughout the system.  Well I ended up putting a full 12 ounce can into the low pressure side however the compressor never clicked on.  I shut of the engine and almost immediately the system was at zero on the gauges.

 

Am I on the right track in thinking that since the compressor never came on that the leak must be in hose between the low pressure Schrader valve and the compressor itself?  I put the sniffer on that part of the hose and it did indicated a leak, however it wasn't obvious under bright light.  I know those sniffers can give false positives sometimes so I wanted to get the group's thoughts before I invested in a low pressure hose.

 

thanks!

[porcupine73]

If it's losing vacuum that fast a mechanic's stethoscope might possibly be helpful. Just get somewhere quiet like in a garage if possible and after shutting off the pump move the end of the stethoscope around the hoses fittings shrader valves condenser etc and see if if you hear any slight noise of air. It might not work but I"ve had good results with the stethoscope in other situations; I was surprised how helpful it can be.

[Fairtax4me]

The compressor won't turn on because you have a HUGE leak! You can't get the system up to the minimum pressure to allow the compressor to turn on because its leaking out almost as fast as you can put it in.

Add some refrigerant to the system with the engine OFF and listen for the hissing sound as the refrigerant escapes from the source of the leak.

 

General source for large leaks is the condenser. Rock or a stick puts a hole through it. The bottom corners of the condenser tend to corrode because they get exposed to salt, dirt, water.

[palfer]

Thanks Fairtax.  No luck noticing anything upon adding more refrigerant this morning.  I pulled the condenser hoping I'd find something obvious based on the leak I have but couldn't locate anything.  It's certainly banged up but spent about 30 minutes combing it carefully and while plugging one end I blew compressed air into the other side, still no signs of a leak. 

 

Scratching my head at this point.  Don't want to guess and replace a part hoping, kind of stuck right now.

[idosubaru]

schrader valves and hoses are most likely.   they fail often and I'd suspect would be more likely to vary like you've experienced over time - leaking sometimes and not others based on heat cyling, engines, etc. 

[Rooster2]

Have you use the florescent dye in the system to detect a leak?? It has helped me in the past.

[palfer]

thanks for the responses.  Yes, I've tried to use the dye.  Problem is the leak is so substantial, I can't get enough pressure in the system to have the compressor kick on and distribute the dye.  Think I have two choices, start replacing components one by one and she if it will hold vacuum each time or give in and take it to a shop.  

 

Condenser is too bad but are there any aftermarket sources for the hoses/lines?  Costs from the dealer are outrageous.   

[Rooster2]

Have you use the florescent dye in the system to detect a leak?? It has helped me in the past.

Telling the rest of my past story..........I finally gave up trying to find the leak myself, so took to a shop, where they diagnosed with the dye. I asked to see where they found the leak, so they showed me. The shop wanted to replace the bottom tube that connects to the condenser, (where the leak was discovered) and the condenser. Total repair bill was pushing $600. I said "no thanks," paid them about $80 for the diagnosis. After looking best I could at the leak, it appeared that my problem was simply a pin hole leak in the tubing, and that is what it turned out to be. I went to a wrecking yard, and secured the tubing there from a Leggie like mine. Swapped the tubing with new O rings on both ends. Added a half can of 134 to the system, then vented out 134 to get rid of some of the atmosphere and possible water in the system. Didn't feel good about venting intentionally to the atmosphere, but that is what happens when you have a leak anyway. So, what the heck. Then added 2 cans of 134. A/C has worked great ever since, and that has been 3 years ago.

 

Bottom line........you may want to go to a shop, and get their diagnosis only, then do the work yourself, and save some money.

[Loyale 2.7 Turbo]

... Bottom line........you may want to go to a shop, and get their diagnosis only, then do the work yourself, and save some money.

 

That is Good Advice, I've done exactly the same in the past.

 

Kind Regards.