air conditioning

[scottinAZ]

Ok, so its almost that time of year here again in AZ, and the AC needs to be working. I have the full system installed in the car, and electrically tested, however it has a leak somewhere. It is still set up for R12, and has the Behr/Bosch compressor in it still. No signs of leaks or failure of the compressor, but I have read that this type of compressor is incompatible with R134A. Without going too deep into the system, I want to convert and recharge the system with 134A, as I can do it myself without a license, and if I blow a line, or the compressor turns to shit, Im not out much. I am familiar with the procedures of a retrofit, so that isnt the issue.

Now for the questions.

1) does anyone know why the original type compressors are incompatible with 134A?
2) one of the pressure switches on the reciever dryer is no longer used, do I need to jumper the wires together, or leave them open circuit?

I will do a full retrofit if I need to, if and when the rest of the system is proven good, but im not gonna drop 500 bucks into a retrofit kit if the condenser or evaporator is shit (without knowing it first)

also anyone with experience on the retrofit compressor kits, I would like to know where you sourced it from, cheapest I have found is about 450 bucks, and uses a sanden 508 compressor. I see that it needs a new bracket, but I dont see the provisions to adjust the belt. pics, and or a decent description including how complete and trouble free would be nice. I can part shit together on my own, I dont need to pay someone for a half assed "kit" to do it for me :D

[jlevie]

There are several R12 replacements other than R134a that are compatible with any system designed for R12. Freeze12 being one that has worked well for me.

Both the low and high pressure limit switches in the receiver/dryer should be connected and used. Off hand I don't know if those are NO or NC contacts.

[scottinAZ]

ok, to electrically test the system, both switches need to be jumpered out, so they would be NC type switches. According to realOEM, there is only one switch available, as both references are to this part number. This tells me that one of the switches is redundant, and can be removed, the question is what one is it? I will most likely have to do some more research on this, as if I jumper the high limit, and its the low pressure that is no longer used, a detrimental condition could be created.

Im not too hot on the R12 analogs, as some contain butane or other flammable substances, not to mention I no longer have my R12 gauges. I DO however have R134A gauges readly avaiable for my use, and several pounds of the refrigerant.

[scottinAZ]

ok, well I did what I said I wouldnt do, and I used Freeze 12 in the system. I first pulled a good vacuum on it (27+") and it held with no problems, so I was naturally reluctant to open the system unneccisarily. Charged with refirgerant, and with the idle set to about 1500-2k rpm, Im running 30 freaking degrees out the vents.

I can be happy with this, but even if the system shits itself, It now has some leak detector dye in it to help with the repairs (if needed), and the system has been cycled to ensure operation (no surprises like a plugged condensor, or blown evaporator)

I think I'll hold off on the full conversion until the compressor craps out (still the bosch/behr unit with viton seals) as the Freeze 12 is a 134a blend, and this will supposedly eat the rubber in the compressor seals. I guess time will tell.

To be honest, Im a bit surprised at the performance of the system, considering that it was sitting nearly empty for god knows how long, and the general design of the system, being from a country that doesnt get that hot.

As for the switches, they are both currently hooked up. the freeze 12 runs a similar pressure curve to the original R12, but when I convert, I will replace the high limit switch with one more suitable to the pressures of 134a. All things for another time, but for now, I can go and freeze my balls off in style at least

[u3b3rg33k]

I put duracool R12a into mine (which is still set up for R12), and it works like a charm. It's not terribly expensive, either.

[scottinAZ]

it was the same price as 134, however, I had to find my AC cert, as it IS regulated by the fucking EPA. oh well, it was a bit of a pain in the ass to find it, but hey, at least I had the damn thing. (havent worked as a pro tech in about 10 years)