A/C question for 1987 Chevrolet Silverado R10

[lilred87]

I just dropped a reman 350 on my 1987 Chevrolet Silverado R10. I installed a new AC compressor, accumulator, and condenser. I'm trying to find out how much freon and oil is used for my truck. Also what type of oil?I will be using r134. Any help is greatly appreciated.

[Puzzled]

Help anybody, got a 86 gmc 1ton dually, developed a ac blower problem, won't blow on 1 low or 2med or high when switched on will blow on high if you thump the relay but when you drop back to med position it quits blowing again, back to high rethump the relay and blows again on high i have replaced blower motor, relay, resistor and cleaned and relocate ground no change in problem anybody have any idea whats wrong with this boat anchor

[DieselSJ]

Originally Posted by lilred87

I just dropped a reman 350 on my 1987 Chevrolet Silverado R10. I installed a new AC compressor, accumulator, and condenser. I'm trying to find out how much freon and oil is used for my truck. Also what type of oil?I will be using r134. Any help is greatly appreciated.

Charge of R134 is roughly 85% of the charge of R12. If you went to a different style condenser, then you would have increased your system capacity. You will probably need to charge based on pressure and vent temps. Use the oil recommended by the compressor mfg. IIRC I used 8oz of PAG46 in mine, but as I went through different compressors it seemed that each MFG wanted a different oil. Be sure you flush the factory fill of oil out of the compressor so that you get an accurate oil charge. Pour half of the oil into the accumulator, some into the ports of the compressor (then rotate compressor slowly by hand to coat the parts, then the remainder in the high pressure hose coming off the compressor.

[chengny]

Add PAG 100 oil in quantities as below and close the system up.

•Compressor- (1 ounce)
•Evaporator - (3 ounces)
•Condenser - (1 ounce)
•Accumulator (2 ounces)

As DieselSJ suggests:

When an R-12 system is retrofitted to 134a, the general rule of thumb is that the refrigerant capacity/charge should be reduced to 80-90 % of the original capacity.

The original GM spec for these trucks was 56 ounces of R-12. So, if we take 56 ounces of R-12 and multiply it by .85, we get a 134a charge of 48 ounces.

[RUN GMC]

40.5 oz is what I used 4 oz of oil and 18 oz & 2 12 oz r-134 cans plus a little left over in one to see the sweat on the metal part of the hoses.......the 18 oz freon can i used had oil in the mix......

[DieselSJ]

Originally Posted by chengny

Add PAG 100 oil in quantities as below and close the system up.

•Compressor- (1 ounce)
•Evaporator - (3 ounces)
•Condenser - (1 ounce)
•Accumulator (2 ounces)

As DieselSJ suggests:

When an R-12 system is retrofitted to 134a, the general rule of thumb is that the refrigerant capacity/charge should be reduced to 80-90 % of the original capacity.

The original GM spec for these trucks was 56 ounces of R-12. So, if we take 56 ounces of R-12 and multiply it by .85, we get a 134a charge of 48 ounces.

I agree with everything above, but don't assume that PAG100 is OK. Use whatever oil is recommended by the compressor mfg. For example, a quick google search says to use PAG150 in a GM HR style compressor. However, the docs that came with my compressor said to use PAG46.