Best approach for fixing inop R12 A/C system

PlayingWithTBI said:

That's fine but, when you're driving around in the heat of the day, shut it off for a few minutes to go shopping or eat lunch, come out and restart it with A/C on, it'll spike way over 430 PSI. I did that and it blew the high pressure switch out of the back of the compressor - sounded like a shotgun going off. Luckily enough I had another compressor with a smoked clutch so, I changed the clutch out of this one (since the snap ring groove was blown out too), and installed the other one's clutch. Have been running it for a few years now, after I wired in the HP switch so it worked like it's supposed to. Not just close the recirc door. The original R4 compressors came with a blowout valve so it'd let a bunch of refrigerant out to prevent blowing a hose or ruining the compressor. You just had to replace that valve and charge it back up I'm sure EPA just loved releasing all the R12 into the atmosphere

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The compressor I took off had that blow off valve. I would think it would blow the high side hose before it would explode the compressor. I'll have to research the overpressure switch.

PlayingWithTBI said:

That's fine but, when you're driving around in the heat of the day, shut it off for a few minutes to go shopping or eat lunch, come out and restart it with A/C on, it'll spike way over 430 PSI. I did that and it blew the high pressure switch out of the back of the compressor - sounded like a shotgun going off. Luckily enough I had another compressor with a smoked clutch so, I changed the clutch out of this one (since the snap ring groove was blown out too), and installed the other one's clutch. Have been running it for a few years now, after I wired in the HP switch so it worked like it's supposed to. Not just close the recirc door. The original R4 compressors came with a blowout valve so it'd let a bunch of refrigerant out to prevent blowing a hose or ruining the compressor. You just had to replace that valve and charge it back up I'm sure EPA just loved releasing all the R12 into the atmosphere

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This probably won't surprise you guys, and I'm not saying it's great for the environment but most of the refrigerant changes come about because dupont loses their exclusive patent, so they have the next one ready, convince politicians this new one is more environmentally friendly an bam, new regulations, "ban" the old one they secure another 10 yrs or so as a sole supplier. It's pretty much already happened with 134 in OE stuff an it's all 1234yhf(hfo) now. That ones time will be up shortly. At least they haven't banned 134a yet but it was 5.98 last summer, now it's 9.98 for 12 oz....

You are supposed to reclaim 134 still and hfo can be vented to atmosphere but it's also much more flammable. Make that one make sense

Yeah,when I ordered my manifold gauges they sent me a set for 1234yf so I researched it. Seems the freon itself is not that flammable until you add the oil. I pictured a high side hose blowing out on a hot exhaust. Uh,no,I'll pass on that!

someotherguy said:

I don't own a vacuum pump or A/C gauge set and not sure if they're a wise investment for me at this time, though I'm not necessarily against owning these tools. With 4 vehicles to maintain, it's not out of the question.

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I have a set of Blue Point gauges that I bought back when I was a dealer tech. They sat on my shelf for years, but the first time they save you $200 they pay for themselves. One of my kids wrecked his car, and after putting everything back together he wanted to fix the A/C. I bought a cheap single-stage vacuum pump from Amazon and with the gauges we got his A/C blowing ice cubes.

Erik the Awful said:

I have a set of Blue Point gauges that I bought back when I was a dealer tech. They sat on my shelf for years, but the first time they save you $200 they pay for themselves. One of my kids wrecked his car, and after putting everything back together he wanted to fix the A/C. I bought a cheap single-stage vacuum pump from Amazon and with the gauges we got his A/C blowing ice cubes.

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I installed one of those under dash units in a 79 Malibu that came with no A/C. I used factory engine brackets and an R4 and had to have the hoses custom made. That thing literally blew chunks of ice.

Scooterwrench said:

Yeah,when I ordered my manifold gauges they sent me a set for 1234yf so I researched it. Seems the freon itself is not that flammable until you add the oil. I pictured a high side hose blowing out on a hot exhaust. Uh,no,I'll pass on that!

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At work the cabinets on the hfo filling equipment are constant positive pressure ventilation an monitored in case of a leak. Anything detected over 15% in that cabinet automatically triggers the fire alarm an calls the on site FD. Turning off the power to the cabinet does the same thing, an yes they hate me

I am not going to give you advice but I will tell you what I have done more than once. I have replaced R12 with 134A by performing a simple flush nothing fancy. Since it sounds like you will need a new compressor then replace it with a 134A compressor with high pressure switch and a new orifice valve for 134A. I would really advise a dual stage vacuum pump (Harbor Freight for $139.95) and a set of gauges as it is a good investment and almost impossible to do a good job without these items. Take care of them and they will be with you for many years. I never replaced the drier or condenser (or compressor) unless they had a problem. These converted systems ran for many years without a high dollar complete change out of the system. I did add about an ounce of oil over what was needed or came with the compressor. Pull your vacuum down to at least 1000 microns or 500 if it will and hold it there for at least an hour. Your drier will give up its moisture during this time.

Its not illegal to purchase r-12, just to manufacture it. Any 609 certified auto a/c tech can procure and install it, and there are also “r-12 replacement” refrigerants that you can use (not sure what’s in them but I had used them in the past after r-12 was pulled from the shelves) that I had success with…just sayin. If you get your compressor running and can do a sat vacuum leak test then that could still be an option for you.

Is your system still charged?

My thread on Suburban part numbers isn't comprehensive but may help.