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2005 Mustang sat for 4 years - A/C is system is empty

Posted: Sat Jan 25, 2020 7:45 pm
by aja8888

New guy here with an inherited 2005 low mileage (62,000) V6 Mustang. It's running now with new tires, etc., but the A/C is not working. The car sat in a garage for 4 years and was not started or driven. Low side pressure was checked by me with a hand held gauge and reads zero. I am assuming the system is void of freon. Plus, the compressor does not kick on. According to the previous owner, A/C was operating when parked 4 years ago.

I'm an old guy (over 70) but have spent my free time working on cars since I was a boy. I have never messed with auto A/C systems but I am tired of hearing about high priced shops needed to fix this stuff.

I'm going to pick up a set of gauges and a vacuum pump and see of the system holds a vacuum. From there, my questions are related to where to get the correct dye check/kit and once I find the leak(s), what should be the next steps (besides replacing parts)? Pull another vacuum and hold for awhile? Recharge? What about oil addition?

I guess what I really need is a strategy to attack this issue with the correct procedure.

Thanks in advance for any guidance you can provide.

Re: 2005 Mustang sat for 4 years - A/C is system is empty

Posted: Sun Jan 26, 2020 11:54 am
by B52bombardier1

My guess is that an o-ring seal dried out from sitting so long. The compressor oil tends to separate from the refrigerant after a while thus allowing the o-ring to leak. So don't be surprised to find a leaky o-ring.

You might try adding a can of refrigerant with oil mixed in already to see if you can revive the system. Of course, do this after pulling it down to a vacuum to eliminate air and moisture from the system. Your receiver-drier / accumulator might already be saturated with moisture so consider changing that out.


Re: 2005 Mustang sat for 4 years - A/C is system is empty

Posted: Sun Apr 19, 2020 5:00 pm
by atikovi
If it was my car, and I have had some sit for longer than that, I would run the pump 15 minutes and see if it's got a vacuum down to 30 inches. If so, shut off the pump for another 15 minutes and see if it holds that vacuum. If it does, vacuum another 2 hours or so and then charge to specs. If the seals were dry and shrunken, just using the a/c will circulate oil to the seals swelling them enough to make a tight seal. Chances are that may be enough to solve the problem, and even if only last a season and you have to top it off every year, that would be fine for me.