Engine Size: 250
Refrigerant Type: R12
Ambient Temp: 68
Pressure Low: 0
Pressure High: 0
Country of Origin: United States
I originally posted this problem in November, 2011. I bought a used 1979 Ford Granada in October, 2010. I noticed that the A/C didn't blow cold before I bought the car. I pushed in the Schrader valve and saw no refrigerant. When I got the car home, I performed a vacuum test and the system held 28 inches of vacuum for an hour. I charged in R12 and the system blew 42 degrees cold. Last year around October there was no cooling. I again checked the Schrader valve and found no refrigerant. I performed another vacuum check and found the system would not hold a vacuum. I checked and replaced every O ring but stlll no joy. I then connected a nitrogen tank and pressurized the system. I put a handful of soap bubbles at every fitting but couldn't find a leak. A couple of responders suggested an input shaft seal leak at the compressor. They suggested injecting dye and pressurize with R12 but I didn't want to waste any refrigerant. I finally bought a new rebuilt compressor and the system is once again gas tight. I pulled 28 inches of vacuum and it holds hours later. I will next install a new filter/drier and charge in some R12 and hopefully I will once again be able to drive this car with air conditioning.
Seal replacement would have been a whole lot cheaper, but glad to hear the system is all good now. Hopefully the rebuilt compressor was good quality, or you'll end up cursing having replaced an otherwise good compressor, save for the leak.
Thanks for the follow-up.
I looked into trying to replace the input shaft seal myself but decided not to after adding up the cost of the special tools and parts needed. I also don't have the experience I felt was needed to attempt the job.
I had to remove the condenser to remove and install a new filter/drier. I didn't have to remove the condenser in the 1978 Ford Granada when I removed the filter/drier. I went ahead and cleaned the condenser while I had it out of the car. I charged in 3.5 lbs of R12 as measured with a digital postal scale. My compressor requires 4 lbs but I wanted to see what the system will cool to with only 3.5 lbs. I placed my R12 cylinder on the scale and it measured at 14.3lbs. The scale is accurate to .2 oz. I connected the gauge set and revved the engine while watching the postal scale. When I saw close to 10.8 lbs on the scale, I stopped charging. As I was charging the system, I kept watching the small temperature gauge. It went to 45 degrees only. The car always cooled to 42 degrees with the original expansion valve, compressor, and filter/drier before the input shaft seal failed. I did everything in the garage and the temperature in the garage was probably 68 degrees F at the most. I'll go out tomorrow and see if the A/C gets any cooler.
I sure wish I know what I did back in 1997. The bearing of the rebuilt compressor I installed several years earlier failed. It made a terrible screeching sound whenever I turned on the A/C. I bought a new rebuilt compressor, a new expansion valve, and new filter/drier. The A/C cooled to 15 degrees continuously! I had to turn off the A/C after a few minutes as my teeth would chatter. I don't know what I did differently. I put in mineral oil, ran a vacuum test, and charged in the R12. I didn't do anything differently today.
If the system calls for 4 lbs of R-12, then by all means charge 4 lbs. A half pound of refrigerant can make quite a difference.
If the system cooled down to 15F, then the thermostatic switch is bad or misadjusted. The evaporator will freeze up. Does the compressor ever cycle, even on the lowest blower setting? I don't seem to remember the Granada or Monarch using a POA for evaporator temp control.
Speaking over evaporators, after some 35 years, it's probably a good idea to clean debris from the evaporator coil and case. A good flushing out can do wonders, especially if this was a smoking vehicle.
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