PFF - Pennock's Fiero Forum, PDA Edition

AC R12 recharge (Page 1/1)

saving_rossi

SEP 07, 09:51 PM

My fiero has not been converted to R134a. I have multiple parts for both an R134a conversion, but I also have $300 worth of R12.

I have a new accumulator and r134 fittings, and r134. I don’t have the seals or the orifice, but my car spent most of its life in a heat controlled garage so there is likely no leak. The AC blows, just not cold. I know the compressor is running too because I can hear the belt start to spueak a little.

I don’t think I want to convert to R134, but I am still open to it.

If I just recharge with R12, I don’t need to replace the accumulator right? Or the seals?

Additionally. I am actually missing one can of R12 because it exploded. I left it in my car and then immediately got sick, so I didn’t notice the heat wave. I technically might not have enough to fully charge the system. Does it matter though?

I know this is so many questions. Thank you to anyone who read this and replies ❤️

RWDPLZ

SEP 07, 10:14 PM

Even if the car is kept in a climate controlled garage, the seals are likely on the verge of failure just due to age of the rubber, now at or approaching 40 years old, depending what year the car is. Best to verify first pressure in the system, and see if it still contains refrigerant. If the system is empty, easy to start. If it still contains R-12, given the current price of R-12, some A/C companies may be willing to recover it for you no charge.

What year and engine? That would determine which system it has, DA6/HR6 or V5 compressor.

quote

If I just recharge with R12, I don’t need to replace the accumulator right? Or the seals?

If the system is just slightly low, adding R-12 might get it functional again, barring any issues with old rubber seals failing. The accumulator contains desicant that removes moisture from the system, if it isn't fully saturated by now, it might be okay. If you open the system for service, it absolutely needs to be replaced. The bag in the accumulator containing the desciant could rupture and spread it into the system, including right into the compressor suction port.

Total Fiero R-12 capacity is 2.5lbs, most R-12 cans were 12-14oz, how much it needs depends how low it is.

First step is to hook up a gauge set and see what the pressures are on the high and low side. R-12 gauge sets are still readily available on eBay. Check against a static pressure/temperature chart

https://www.hudsontech.com/...emperature-Chart.pdf

If empty, convert to R-134A. If slightly low, top off and check operation, or have recovered and convert to R-134A.

Dennis LaGrua

SEP 08, 03:13 AM

Recharging with R-12 will be expensive and doesn't solve the problem if you have a leak Converting to R-134a is worthwhile, but you will need a new accumulator, orifice tube, adjustable low pressure cutout switch and replacement green O rings. Most of the old 525 mineral oil also must be removed and replaced with Ester oil. The system evacuated and tested before recharging. If done correctly, the conversion is worthwhile. My 87GT A/C system blows cold on the hottest days.

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" THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

Brian A

SEP 08, 11:03 AM

The problem with R12 is that it is both a greenhouse gas and an ozone depleter. R134 is "only" a greenhouse gas.

I cite this to say that it is critically important that you ensure there is no leakage in the system before recharging it. That your compressor operates is not a test of system functioning properly. If the system has bled down to 0 psi, you definitely have a leak somewhere. Once the leaks have been fixed, pressurizing the system to about 100 psi and confirm it holds that pressure for 24 hours or so.

If you are converting to R134, yes the accumulator will need to be changed, the whole system flushed and the compressor oil would need to be changed. Opinion varies regarding the necessity to change evaporator valving (orifice tube, expansion valve etc.). (It's good "hygiene" to change the accumulator any time you open up the system regardless of the type of refrigerant).

My experience with commercial shops is that they won't come near R12 anymore. There is too little demand, few technicians have licenses to use it and there are too many legal liabilities for them.

Here is a good book regarding vintage automobile air conditioning systems:
Just Needs a Recharge: The Hack Mechanic Guide to Vintage Air Conditioning

Dennis LaGrua

SEP 08, 11:41 AM

I have found that when recharging most of the old mineral oil sits in the condenser. If a small bit remains thats OK. Not a big fan of running flush through the system as it could remove the old oil barrier coating inside the lines. I just blow out the open hoses with compressed air, install all the new parts and then take the system down to about 29" hg with my vacuum pump. If the vacuum holds for few hours then I'll vacuum again and then recharge with the right amount of R-134a. I would avoid using R-12 . Its next to impossible to find, very expensive and its bad for the environment. An R-134 conversion done correctly will provide cooling even in 98* weather.