AC system not holding pressure… where to start?

[zcostilla]

2005 LX470 and the air worked fine until about two weeks ago, when it started running weak. Was meaning to get to looking at it, but one of the fine joys of being disabled is finding that sweet convergence of feeling well enough to do the work, having time to do it, and weather to cooperate since I don’t have a garage in this hot and muggy (and buggy) South Carolina summer. Anyway, yesterday the warmer temps had me initially suspecting an over pressure cutting off the compressor, but when I checked it, it had a whopping 2 or so PSI. Last evening I used a can of refrigerant from Advance Auto that included stop leak and let it run, and got it to 35 PSI and it was back to freezing me out inside the cab, but when I checked it this morning it was back down to 10 PSI. I filled it again and will continue to monitor it, but I suspect that something is going to need replaced.

So is there a usual suspect that I need to begin with, or is this best left to a shop since I don’t have a vacuum pump and have minimal HVAC experience? I need to get it fixed before heading to Myrtle Beach next week.

 

[awesomeissquid]

To investigate you would have two options. First would be to look over all the lines to see if you can spot an oily spot where the refrigerant and oil has leaked out. Since that is sometimes not obvious, you would then add some UV due to the system so you can track the leak down with a UV light.

Since you have trip coming up so soon I would probably take it to a shop for at least the initial diagnosis. From there you can decide if you want to do the repair or have them do it.

I believe a common spot for issues is the rear AC lines and that most just cap them.

 

[ceylonfj40nut]

Harbor freight has an electronic nose thats cheap that can detect a freon leak. Saved me many hours of closing in on the leak. Especially in the dash leaks. Beeps when it finds the source.

 

[Gnarwgn]

Based on what I've learned so far this summer - common culprits include the rear high pressure line (pinhole leaks develop at the 3 clamp locations), and any connection point in the system where seals eventually fail.

I'd agree with the previous comment that if you have a trip coming up, take it into a shop to at least get diagnosed if not repaired. You can burn alot of time chasing an AC leak...I hear. Haha.

 

[OEMGUY0720]

Last evening I used a can of refrigerant from Advance Auto that included stop leak and let it run, and got it to 35 PSI and it was back to freezing me out inside the cab, but when I checked it this morning it was back down to 10 PSI.

Symptom indicates pressure loss hence a leak in the line. Could be a tiny hole in the line, could be a leak in the evaporator and/or expansion valve. I would recommend using a refrigerant with a dye and trace it with a UV light. This eliminates the guessing game. Fix the leak and observe again.

If you are able to feel the ac is venting biting cold, this also should tell you the compressor is doing its job and is fully operational. 98% positive your AC has a refrigerant leak somewhere. Good luck and keep us posted.

 

[zcostilla]

Well the system is still reading good, 37 PSI today, more than 24 hours after I topped it off. Hopefully it was just a seal that needed some reconditioning and the stop leak will have addressed it. I’ll definitely keep checking it and schedule an appointment if it ever starts to drop. And I’ll take my gauge with me to Myrtle Beach in case I have to throw in another can if it acts up to buy time to see a mechanic.

 

[fyrftr007]

So what are the components for the rear AC? I have a GX470 but am in contact with a FS 2004 LC 100. The owner says the AC doesn’t get cold.
I have experience with AC systems, but I am not certain what all is included with the rear climate control on these 100 series.
didn’t intend to hijack the thread, but with the issues mentioned it seems relevant.

 

[zcostilla]

So what are the components for the rear AC? I have a GX470 but am in contact with a FS 2004 LC 100. The owner says the AC doesn’t get cold.
I have experience with AC systems, but I am not certain what all is included with the rear climate control on these 100 series.
didn’t intend to hijack the thread, but with the issues mentioned it seems relevant.

Not sure at all. My issue was up front. I didn’t even check the rear AC.