Engine Size: 250
Refrigerant Type: R12
Ambient Temp: 68 F
Pressure Low: 0
Pressure High: 0
Country of Origin: United States
I posted last year about a Ford Granada I bought in August, 2010. Before buying the car, I checked the A/C and saw that it wasn't blowing cold. After buying the car, I pushed in the schrader valve and found that there was no R12 in the system. I performed a leak check and when the vacuum held, I charged in some R12. The A/C went to 42 degrees immediately. Earlier this year the A/C was blowing 47 degrees so I added a little more R12 but still got only 47 degrees. This Tuesday the A/C wasn't cold at all. I again pushed in the schrader valve and found no freon. I did a vacuum check and pulled 28 inches. After 30 minutes the vacuum was down to 27 inches. Another 30 minutes and the vacuum went to 26 inches. Eventually the vacuum went to 0 inches. I replaced the O rings at both ends of the low and high side pressure hoses, expansion valve, and compressor, a total of 9 O rings. The old O rings were fine but I replaced them with new ones anyway. I put everything back togtether and the slow leak is still there. Since working on my 1978 Ford Granada beginning in 1980, I never had a slow leak. The vacuum always held. Can anyone suggest how I can find this slow leak?
either dye it up or use a sniffer. Most common leak left to check is compressor shaft seal. Pressurize system and place a shower cap or plastic bag on front of compressor overnight. Stick sniffer in there next morning and see if it detects a leak. Instead of wasting R12, troubleshoot with r134. If you have access to nitrogen, use a trace of refrigerant and nitrogen to pressurize system.
You siad you replaced all orings but did you clean the fittings with dental floss and superfine sandpaper?
If you still have the 1979 drier on there (NOT a good idea) it may not be R-134a compatible. Just to clarify, testing with R-134a means you put a few ounces in to get maybe 50 psi of static pressure. Do not run the compressor, unplug it to be sure it will never run. Leaking down to zero is not a slow leak.
Thank you Dougflas and mk378 for your input. I have a 1978 Ford Granada with an identical A/C system. I will remove its compressor and install it into the 1979 to eliminate the compressor as the source of the leak. If the leak turns out to be the evaporator, I won't go into the dash to remove it. As I stated in a previous post, the last time I worked on the A/C on the 1978 Ford Granada was in 1997. I installed a rebuilt compressor I bought from Kragens, a new drier, and a new expansion valve. I put in new oil and charged in R12. To my amazement, the A/C blew as cold as 15 degrees continuously. It got so cold my teeth would chatter. When it was 90 degree outside I never felt the heat inside the car.
I decided not to remove the A6 compressor from the 1978 Ford Granada because the system is gas tight and still cools to 40 degrees (before slowly increasing to 50 degrees). Instead, I bought a nitrogen tank and nitrogen and pressurized the leaking AC system to 125 psi. I put a handful of soap bubbles around every hose fitting, the filter/drier, metal tube that connects to the expansion tube, and under the expansion valve. I watched and saw no bubbles created by escaping gas. The next thing I want to do is immerse the front of the compressor under water. Will I damage the compressor if I try doing this? I want to check for leaks from the input shaft seal. If this is a bad idea, I'm going to charge in some R12 (I only have 14lbs left from a brand new 30 lb cylinder I bought back in 1997) along with UV dye and check for leaks with a UV light.
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