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By Richard - Sunday, April 19, 2020 5:00 AM
In 2004, I bought a 1971 D300 Dodge truck . It was just a C&C and had not been on the road for some years. Only 60k miles showing. I did learn that it had been a dump truck and ordered with every option in the book --A/C. ,carpet interior, tinted window, 383 4bbl V8 --the works. I spent some time and $$$ --had it painted, 10 ft. steel body made, dual stacks installed, and a Spicer aux. fitted. Then I sold it. Fall of 2018, 14years later, I bought it again (not from the guy I sold it to) with 4k miles added The A/C had not worked when I bought it in 2004. The heater core was shot and finding one that was for A/C proved impossible. A few months ago, I decided to use the A/C as an air pump. All the A/C hoses were long gone. I hooked the compressor to 12v and it started pumping!!! So air tank, hoses , on/off switch, pressure gauge in the cab, etc fitted and time for the BIG test, It pumped up to about 8 lbs, then the compressor clutch started to slip! It "chirped" and would not pump any higher. SO MY QUESTION AT LAST Should I replace the A/C clutch. Not a big or expensive job, but I now have more $$$ invested then I wanted to---not too difficult with old trucks. I did check the clutch clearance and it is only about .005 when about .020 I think is normal, OH, I have not fitted a one way valve yet--got one but not correct fitting--don't know if this matters or not. Thoughts???, and thanks.
By Geoff Weeks - Sunday, April 19, 2020 11:59 AM
RV-2 compressor? A/C compressors have no oil control ring and no cooling fins or coolant lines. They will pass the oil into the compressed air and seize when oil get low or the piston will seize when they get hot enough to expand in the bore.
Add to that it may have a EPR valve in the intake of the compressor. Its propose is to maintain the pressure in the evaporator at a pressure that keeps the evaporator from freezing over, around 30 psi for R12.
With the EPR in the intake it will restrict the flow because the inlet is blow 30 PSI
If you want air, put an air compressor on, don't use an A/C compressor. when it runs, the returning refrigerant is around freezing and carrying some oil with it. It cools and lubes the compressor with cool oil, Warm air, and no oil will mean the compressor will not last.