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Question about capacity of modified system

rt707 on Fri July 02, 2010 1:35 AM User is offline

Year: 79
Make: Ford
Model: Ranchero
Engine Size: 351m
Refrigerant Type: R12
Country of Origin: United States

Hello everyone, Ive totally rebuilt the A/C system on my Ranchero and now have a question about its refrigerant capacity. Here's what ive done, New 10 cu. in rotary compressor in place of original York, new parallel flow condensor, all new barrier hoses made by me, new receiver/drier and new TXV. Only original components are STV/POA and evaporator. Should i just charge via the sight glass now or charge it to the original system capacity of 4lbs 8oz? I will be using R12. Thanks for any and all help.

bohica2xo on Fri July 02, 2010 3:32 PM User is offline

Refrigerant charge with the sightglass is fine. Bring the engine rpm up to 2000, and clear the glass with the cabin fan on the highest setting.

The bigger issue is the oil charge. Hard to say what is "enough", and too much will hurt performance. The proper method is to charge a generous "guess", then obtain a liquid sample from the system while running. The sample is weighed, the refrigerant is recovered. The remaining mass is oil.

The goal is 6% to 10% oil by weight in circulation depending on the compressor manufacturer.

I do know that the OEM York charge will be a lot of oil for a PF condensor & sumpless compressor. It may not cool great, but it will not kill the compressor...


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