A/C question

[73pony]

I will have access to a set of R12 gauges Friday evening as well as some R12. Does anyone know the correct high and low side pressures for a 73 with factory A/C? I know the total freon is 1 lb 12 oz of R12. I just need what the pressures should be with the engine running and A/C on. I just want to know what the high and low pressures should be at 80 degrees ambient outside temp. Or if there is a chart some where that would be great. Thanks. Jason.

 

[piper62j]

I will have access to a set of R12 gauges Friday evening as well as some R12. Does anyone know the correct high and low side pressures for a 73 with factory A/C? I know the total freon is 1 lb 12 oz of R12. I just need what the pressures should be with the engine running and A/C on. I just want to know what the high and low pressures should be at 80 degrees ambient outside temp. Or if there is a chart some where that would be great. Thanks. Jason.

If you have the original York style R12 compressor, it should hold 1 3/4 lbs. of refrigerant. Normal low side (suction) is 10 - 20 psi and high side (discharge) is 180 - 225 psi. The ford factory manual says it takes 1-3/4 lbs 0f R-12. If you need to put in oil a York compressor takes 10oz. and a Tecumseh 11oz. I did find that you should never let the high side get more than 240lbs while charging.

 

[73pony]

Thanks. That is the pressure range I was thinking it should be. Just wanted to check. It is the original AC system it works but does not cool very well at all.

 

[piper62j]

You may want to replace the receiver dryer before the recharge.. They do get contaminated even though the system is sealed.. Also, perform a complete evacuate and flush once before charging for the last time.. It will insure complete removal of any moisture or contaminants in the system.. If the system oil smells like rancid oil, flush out all the old oil and replace it.. Great, cheap insurance.