1986 Porsche 911 AC Issues

[Jay McGrath]

I had a schrader valve leak and slowly lost R12 to the point the AC was barely cooling. I fixed the leakage problem and at this time was at the point I was not going to put R12 back in for several reasons: cost, environmental and ease of obtaining it today. I have read a lot about a R12 replacement using hydrocarbon refrigerant called Enviro-Safe which cost about $5/can. I won't debate the pros and cons about using this refrigerant, only that it works. I called Enviro-Safe and spoke to their technical personnel and I liked the fact that you only had to use 1/3rd of amount of Enviro-Safe compared to R12 (13 oz vice 39 oz).

With R12 I was barely getting a 25 degree delta T (temperature) between ambient and the center dash temperature. With Enviro-Safe installed which is colder and more efficient that R12 I am getting 38 degree delta T 88 degree ambient (80% humidity) and 50 degree center dash temperature.

My compressor pressures with Enviro-Safe are Low - 40 PSIG and High - 240 PSIG with R12 pressures were 35 PSIG and 225 PSIG. I don't have any history as to what the original AC performance was when the car was newer, but I am told I am lucky to have what I have. I spoke to my local Porsche Independant repair shop, and he told me that they normally shot for 25 degree delta T as sufficient for these older Porsches.

My question, is is 30 to 38 degrees delta T fine with these cars or should I shot for approximately 30 degrees center dash temperature vice the 48 degrees I am getting now?

[flightlead404]

I have most of a 30lb can of R12 in my hangar is someone wants to make me an offer, and pick it up of course

[Bigtoe32067]

Did you evacuate the system before installing the enviro safe?
Tony