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I have a leak and i cannot find it....

mrvmax on Sat June 07, 2008 5:31 PM User is offline

Year: 1996
Make: ford
Model: f350
Engine Size: 7.3
Refrigerant Type: 134
Country of Origin: United States

My a/c stopped working (only blew warm air and the compressor would only cycle on for a couple seconds and then go back off) so when I checked out all the lines/connections I had a lot of oil where my high side fitting was. I found the high side fitting leaking so I replaced it and the o-ring. I also lubed the fitting with nylog. I replaced all the o-rings I can find, at the compressor, drier, pressure switch and connection to the condenser. My vac pump will not pull down lower than 26" after about 10 minutes of use. If I close the gauges then the vacuum starts dropping instantly indicating a leak. I checked my gauges are there are not any leaks on them. I was going to replace the drier so I decided to pressure up the system with 20psi of air before I replaced the drier so I could find the leak. I soaped all connections and I cannot find any leaks. No fittings are bubbling when I add a soap/water solution. When I pressure it up it held 20psi but I cannot hold vacuum. Any ideas on where I may be leaking? Any problem areas? I am trying to figure out how to isolate each component (evap, condenser) to check separately. Any ideas?

Chick on Sat June 07, 2008 8:07 PM User is offlineView users profile

did you check the front of the condenser for any oily spots? Sometimes a stone can cause a leak, also need to check the evaporator, and if you have a steel accumulator with the "blanket" on it, remove the blanket and look for rust.. That should start you off...

Email: Chick


Freedoms just another word for nothing left to lose

mrvmax on Sat June 07, 2008 9:53 PM User is offline

I have soaped down the entire drier ( a little rust but no leaks). I also pulled off half the cover to the evap and soaped that down, I did not see any bubbles (of coarse I couldn't see half of the evap since I didn't pull the whole cover off). The evap looked in good shape. I would think that with 20 psi I could see a leak but I cannot find any. I also soaped down the entire compressor and I do not see any leaks. I guess I'll have to check the condenser better, I'll try and soap the entire condenser (I mainly checked the end of the tubes). The only place I found oil was on the high pressure fitting so I though that was it.
I tried evacuating again and I could only get down to 26". When I isolated the gauges it dropped down to 12" within 10-15 seconds. I still have a leak but I cannot find it to save my life. I used the o-ring kit I bought at AMA a couple years ago for my Toyota Corolla. Are the o-ring sizes that much different that I really need o-rings for Ford? I notice that the Ford kit is part number CP3012 and the Toyota is CP3008. Since I changed out all the o-rings I thought maybe I put the wrong sizes in causing my leak.

Travis on Sun June 08, 2008 12:15 AM User is offlineView users profile

I think you used the wrong orings.

1993.5 Single Turbo Toyota Supra 714RWHP
1985 Suburban
1997 Pontiac Grand Prix GTP

chris142 on Sun June 08, 2008 12:26 AM User is offline

Originally posted by: mrvmax
I would think that with 20 psi I could see a leak but I cannot find
No way. It's off pressure is very close to the ambiant temp. I test them @ 150-200 psi.

mrvmax on Sun June 08, 2008 8:21 AM User is offline

What is the highest pressure I can use when I pressure up from the low side? Today I plan on pulling my grill so I can see the full front side of the condenser. If my leak is not there it will have to be the evap. That is a pain to get to but I may pull it.

mk378 on Sun June 08, 2008 12:44 PM User is offline

I agree probably a wrong o-ring that shifts and opens up a leak under vacuum, but seals (fairly well anyway) against pressure. Compressor shaft seals might do this sometimes too.

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