A/C repair & restoration options

[Pete_89T2]

Originally Posted by jackhild59

Couple of things: as macz said Freeze12 is not HC.

My mistake, confusing Freeze12 with "envirosafe" and a few other products being sold with names similar to Freeze12 that are HC gas based. Point I wanted to make is be careful with alternatives - some may work very well, but have unintended safety risks that aren't worth it

Originally Posted by jackhild59

Next your charge is either very low or it is contaminated. You cannot tell the % charge from the pressure.

You can estimate % of charge remaining from a static pressure test, based on the ideal gas law, but it's a rough estimate. Quick ideal gas law reference:

http://en.wikipedia.org/wiki/Ideal_gas_law

The gist of it is the A/C is a sealed system, so volume is a constant, and the mass/# of gas molecules is supposed to be a constant, assuming no leaks. That leaves pressure & temp as your only variables, and these two are directly proportional. Since I was reading a high static pressure, it means I still have the majority of R12 in my system. Would need to consult with a temp vs pressure characteristic curve for R12 and know the exact mass of the original R12 charge to estimate the percentage remaining though.

Originally Posted by jackhild59

The low side pressure switch cuts the compressor out at +/- 18psi, so that 6 psi number is troubling.

This is interesting, and I probably should take a second look at the electicals... Didn't think I had an issue there since the clutch was constantly engaged while the A/C was on, turning the compressor. Does the pressure switch cut out the compressor ABOVE 18psi or does it cut out below that threshold? If it's the latter, at 6psi, my compressor shouldn't be running at all.

Originally Posted by jackhild59

I think your plan to evacuate and recharge is a good one. Put *exactly* 2-12 oz cans in. Factory charge is 26 oz. 24 is as close as you can get,'unless you find some really old 14 oz cans that sometimes show up on eBay.

Yeah, I'm crossing my fingers on a couple of ebay auctions for the R12, but I might just have to spend the bucks on a "buy it now" deal -- seems someone always outbids me at the last minute on the damned auctions!