| Message |
Save yourself a huge headache and use an R12a refrigerant in the R12 cars. Any of these refrigerants are full compatible with the mineral oil present in your system. Cooling is equal to or possibly better than R12. Redtek or Duracool, etc. Cooling with the R12 Condenser is marginal when converted to R134a. The new-style R134a condenser is NLA from Nissan. I'm talking TT here, NA you may be able to get away with using R134a and still have adequate cooling. The R12 mineral oil in your system is not miscible with R134a refrigerant, having small amounts circulating in the system with R134a and PAG or POE oil isn't a huge issue. But, if you have any moisture in the system, Hydrofluoric acid can form and attack system components. Find someone with a set of R12 gauges or get a set from Amazon, etc and see what you have for system pressure remaining. Check the compressor to make sure it is free and not seized, check the clutch coil to make sure it isn't open.
Legally, you shouldn't combine R12 with R12a, the R12 must be recovered first. Good luck finding a guy with an R12 machine willing to recover your system if you have pressure remaining in the system.
Maybe an aircraft maintenance outfit, as we still use R12 in some small aircraft systems. I personally have an R12 setup as well as an R134a unit.
Replace the receiver/dryer no matter what. You should replace all the system orings with the green ones, as that is usually the issue with the Z32 system, leaking orings at the compressor, or the firewall connections. Just replace them all, including the one on the receiver/dryer pressure switch and prelube them with whatever oil you are using in the system. Be very careful when breaking torque on the aluminum fittings to the evap and condenser, they can become bound with corrosion and just rip the threads out of the fittings or twist the tubes when disconnected. PB blaster, etc sprayed on all fittings for a couple days before attempting to disconnect can help. I have had some success with heating the connections with a heat gun also (not a propane torch).
Other major leakage area is the compressor shaft seal, which is available and can be replaced with special tools.
Replace the valve cores on the service ports. FYI, the Z32 use an oddball HP fitting which needs an adapter to connect to it, I've never been able to find a quick-release fitting to mate to it.
No matter what refrigerant you use, don't use the "conversion" fittings as they are mostly garbage and leaky. If you can, identify the system refrigerant with a label on the AC sticker on the hood or near the service ports for the next poor bastard...
Pull a full vacuum on the system for min of 1/2 hr with a proper vac pump, not a venturi POS. I use a micron gauge and you can see the moisture boiling out of the system on it. I usually pull the system down for an hour.
Leak check the system to ensure you have a good leak-free system. Sometimes I've noticed that an original compressor shaft seal will have a small leak under full vac using the micron gauge, but it will be OK under pressure when the system is charged, YMMV. You can also charge the system with dry nitrogen if you have problems finding a leak. We frequently do this on aircraft as some cracks will draw closed under a deep vac.
Most R12a cans say to not discharge into a deep vacuum, not sure why, maybe separation of the long-chain molecules when it flashes to a vapour? I use an Imperial-Eastman Kwik-Charge adapter and charge with liquid (upside-down can) into the system with the engine off until there is a base charge, then fire up the car and see if the compressor will cycle. R12a will not fully clear the sight gauge of bubbles when fully charged, that isn't an issue.
DO NOT use any refrigerant with system seal/stop leak/seal conditioner/etc in it. You will absolutely have problems in the future if you put any of that crap into the system, UV die is OK. When you replace the dryer, check and see how much oil you can pour out if it and replace that amount before charging.
If you do decide to flush the mineral oil out and convert to R134a, it is helpful to purge the system with dry nitrogen a couple times to clear out all the residue of the oil and solvent.
Also, replace the pressure switch on the dryer with the proper R134a window (binary) switch from a 94+ car to ensure the system works correctly under low and high pressure conditions.
I didn't mean to write a novel, but it's a slow morning at work and this question comes up once in a while.
FWIW, I have an AC cert in Ontario, work on AC systems both in automotive and aircraft.
Best of luck.
|
 |
