240 A/C...where to start?

[dougburgy]

OK...new update!

I've borrowed a vacuum pump and manifold gauge set from autozone so I could pull a vacuum and see if it holds. They take deposit, but give money back when returned! Free tools, and decent quality, love it! Lots of good videos online for this...look for Erick the car guy vid on finding leaks. That one showed me exactly how to use this equipment. Very simple really. I bought the 134a retrofit adapters from autozone for my r12 service ports (finding manifold gauge set with r12 fittings hard to do). Only $10 for those. I used some oaty thread sealing compound after cleaning r12 threads with wire brush and acetone...just to make sure I get a good seal. Also, the adapters come with red loctite type product to make this a permanent things...the thread compound should give me the ability to remove and go back to r12 ports if I want (probably won't though).

I pulled a vacuum for 40 minutes. Went down to 30" quite quick (about 10-15 minutes max). You then turn off manifold gauges, and turn off vacuum pump. You are looking for your system to hold this vacuum. This is how you can determine if system has a leak. After 1 hour, it was still right at 30". Yeah! Even after 10 hours (over night), it was still at a solid 25". Super Yeah! So I know my system is essentially leak free. I could put in part of a can of leak seal as preventative to condition o-rings, etc...but not going to at this point.

I've already checked to make sure compressor kicks on (when jumping low pressure switch) and has no bad noises. I had to hook up the wires, that were in engine bay (from hot firewall wire to one of the wires that go to low pressure switch, then the other wire from low pressure switch to wire that comes from AC clutch). Basically two connectors were undone by previous owner. York compressor low on oil, so I bought a quart of mineral oil (not switching mine to 134a) to top it off. Volvo factory manual I found online (pdf) shows how to check compressor oil and top off as needed. Don't run long when checking to make sure it works....don't want to burn it up in case low on oil like mine. Just a few seconds should tell you.

Parts on the way: New receiver/drier ($18), new expansion valve ($19), Refrigerant can tap ($7), 3 cans of Enviro-safe 12a refrigerant to re-charge. I will used Autozone tools again after new receiver/drier and expansion valve installed. I will then pull vacuum for at least 2-3 hours to boil off all moisture from system. Then I will let system come back to atmosphere (enviro-safe 12a not to to be charged under hard vacuum) and charge through yellow hose of manifold gauge set through LOW side (blue). Envirosafe also has dye in the refrigerant so I can find any leaks if they happen going forward. Autozone also has loaner tool for nice UV light/glasses leak finder setup. If it leaks out over weeks/months....i will add a can of enviro-safe stop leak (great reviews, but only for small leaks...system should hold at least some vacuum for a while) possibly instead of opening system and digging into o-rings job. I'll cross that bridge when I come to it...of course I'll already have new o-rings at drier and expansion valve (under dash).

After I get the above done, and test it out, I will report back.

Another brand other than envirosafe products for R12 replacement is Redtek 12a. Both environmentally safe for ozone, etc (even more that 134a). I looked at both but chose enviro-safe for great reviews and because it's much cheaper. Can get either from Amazon...and many, many reviews from people that love it big time for reviving old classic R12 systems that are now blowing very cold (much colder than the 134a it's reported).

[dougburgy]

UPDATE:
Vacuumed system, replaced drier, replaced expansion valve, checked it holds vacuum (very well, nearly 30" overnight) to ensure it's leak free. Hooked up manifold gauge set, charged system.

Result, poor cooling, but some. Low side pressure is higher than ideal (around 45-50 psi), and high side pressure is way low (around 50 psi) at 2000 rpm with ambient temps around 60 degrees (night time work). From the volvo manuals, I should be around 30 psi low side, and well over 100 psi on high side even with low ambient temps. From the troubleshooting guides in green books, this is telling me "defective compressor". I have no reason to doubt this conclusion, however disappointing it is. But, I'm only about $80 in on this project, for an AC system I knew nothing about. Was hoping for a good ending, but it looks like I'm a new compressor away from a good ending. If anybody thinks there could be another reason for low high-side pressure that would be worth looking at before buying new compressor...please chime in!! Thanks, Doug