1991 Mustang GT w/ R12 - need help

Friendly format provided to inquire about automotive a/c systems.
Archived Forum

Moderators: bohica2xo, JohnHere, Tim

fastsvo
Posts: 16
Read the full article
Joined: Wed Aug 24, 2022 3:55 pm

Re: 1991 Mustang GT w/ R12 - need help

Post by fastsvo »

So the car is not a bad as originally thought. I drove it yesterday and at idle I engaged the AC (MAX AC) and slightly raised the rpm and it started to blow slightly cold air, still no where close to be even considered cold. So it has more Freon in it than I thought.

Pulled it in and started to poke around with a HF leak detector and I got some weird results to the point, where I don't trust it (the Tif would not go off on these areas). Spraying soapy water did not net any results either. At this point, it maybe just the schrader valves are leaking and just needs a recharge.

Some videos of me playing around with the HF tool:

https://photos.app.goo.gl/G3GBq1JdR2Bz8jGt6
https://photos.app.goo.gl/bMaM6Nvtwrs2zudq5
https://photos.app.goo.gl/N95s3As4RS4WVjHp7

All this time, I was thinking the front seal was leaking on the 6P148a, but with 62k miles, maybe that's not the culprit here. Below is a link to the pic of the underside of the compressor and I believe all the dirt is being slung by a leaking power steering unit/line.

https://photos.app.goo.gl/8xEX2nCVYBmFayyw6

Thanks!
tbirdtbird
Posts: 893
Joined: Sat May 02, 2020 1:48 pm
Location: Texas

Re: 1991 Mustang GT w/ R12 - need help

Post by tbirdtbird »

Looked at vids.
What I see overall is overall jumping around with diagnostic attempts.
1. Plastic bag or shower cap not put over comp with belt off overnight to determine shaft leak as suggested. In the trade we do not guess.
2. Hoses are 30+ years old and look very porous and brittle.
3. I cannot comment on the quality/reliability of a HF sniffer, but you have the sensitivity turned up way too high.
4. High side schrader yet to be snugged as suggested.

The car sat for a period of time, allowing the shaft seals to dry up. Mileage is irrelevant here.
When considering your next auto A/C purchase, please consider the site that supports you: www.ACKits.com
fastsvo
Posts: 16
Joined: Wed Aug 24, 2022 3:55 pm

Re: 1991 Mustang GT w/ R12 - need help

Post by fastsvo »

1. I actually did perform the bag test and did not get any response from the leak detector, nor was there any oil inside. though after driving the car yesterday, I have not performed this test again and I think I should.

2. Yes, they are old and I have been considering replacing everything.

3. I am glad you mentioned this. I was going back and forth with 50% to 100% sensitivity. Only at 100% was I really getting those questionable responses. How would you go about it?

4. Coming soon!
tbirdtbird
Posts: 893
Joined: Sat May 02, 2020 1:48 pm
Location: Texas

Re: 1991 Mustang GT w/ R12 - need help

Post by tbirdtbird »

Yes, I would test comp seal again.

We almost never use 100% sensitivity. Maybe 60-80% at most.
Readings need to be reproducible. You need to sniff at the bottom of fitting since refrigerant is heavier than air. If you keep getting a hit on the hoses, they look pretty brittle and porous to me.

Thread is getting lengthy. Can't recall, did you sniff the evap drain tube under the car?
Evaps are famous for leaks
When considering your next auto A/C purchase, please consider the site that supports you: www.ACKits.com
fastsvo
Posts: 16
Joined: Wed Aug 24, 2022 3:55 pm

Re: 1991 Mustang GT w/ R12 - need help

Post by fastsvo »

Yes, I have tested the evap drain hose twice and got nothing from both tools.
Post Reply