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Still learning

Turbofiat on Sat June 25, 2011 8:12 PM User is offline

My custom A/C system on my FIAT Spider is still working great.

Still some questions. The A/C guy over in the valley I talked to told me I could charge the system myself if I had a vacuum pump. He said he had no idea of the volume and his guess was as a good as mine. He said the least he has ever charged a system with was 24 ounces. So that was what I ran with.

I added two 12 ounce cans of R134a. The only thing I could do was monitor the pressures and temperature. I found 12 ounces verses 24 ounces makes no difference in temperature or pressure. So I stopped at two cans.

The temperature coming out of the vents is never below 45F. No matter if it's 95F outside or 70F outside. I can aim my heat pen at the evaporator and sometimes it will show 28F but mostly 34F. That seems to tell me the thermostat is working. Otherwise if it was lower, the evaporator would freeze up. Correct?

Why is R12 so much desirably than 134a? It's twice as expensive but does it work any better? I still have three cans of R12 I've been holding onto since the 90s. If I had added R12 instead of R134a would the air coming out of the vents be colder than 45F?

45F is while the car is moving. a 12X20 condensor was the largest I could fit on this car. I have the radiator fan set up to run whenever the compressor is engaged so at idle the air coming out the vents is more like 50F.

mk378 on Sun June 26, 2011 2:15 AM User is offline

If you have an evaporator temperature switch or sensor, it's going to cool until that is satisfied and then cut off the compressor. As long as the refrigeration system works well enough to do that, it doesn't matter what kind of refrigerant you use. The vent temperature is determined by the switch.

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