whether to convert from R12 to R134 - what is needed? (Page 1/2)
sledcaddie MAY 27, 09:26 AM
Just bought a 1988 GT, V6, 5 speed, 12K miles. Very well maintained car. I am going to have the A/C system checked. Looking at the fittings, it is still R12. If the system doesn't hold vacuum, should I convert to R134? The most recent articles I searched in Pennock's are from 2014. If the conversion is done, can the existing compressor be used? Some have suggested that OEM compressor will work with either freon. Some have suggested replacing the accumulator. Should anything else be replaced? Your thoughts please. Thanks for any experienced input.
Dennis LaGrua MAY 27, 10:18 AM
The proper R12 to R134a involves evacuating the system of any remaining R-12 and mineral oil, replacing the accumulator, orifice tube and any leaking O rings. Then the system is vacuum pumped to 29in HG and should be held there for 30 minutes. If the vacuum holds then recharging with the proper amount of Ester oil and R-134a can begin. This is the abbreviated procedure. For the detailed charging procedure, there are many You Tube videos on it.

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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
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RWDPLZ MAY 27, 02:03 PM
The 88 GT comes with the better HR6 compressor. At this point however, the compressor and seals are 30+ years old. I would at minimum replace the front shaft seal and switch seals if not the entire compressor. I would also replace all the o-rings except the two at the condenser, unless they are leaking. Accumulator is a must due to the desiccant, and orifice tube is also cheap insurance. Original switches can be reused if the connectors are not broken, or converted over to the newer style.

Here's a parts list:

http://www.fiero.nl/forum/Forum2/HTML/000652.html
FX MAY 27, 03:24 PM
...You can get R12 on eBay...I changed over to R134 a couple years ago with just evacuating the system and, installing hose adapters, and nothing else. Cooling is adequate, but will be colder with the changes mentioned...Being that I can get R12 now, I'm thinking about going back to it...Colder...
RWDPLZ MAY 27, 03:52 PM
Most reputable sellers will require proof of EPA Section 609 certification in order to purchase R-12, which isn't difficult to get at all. You should still re-seal the entire system if you do go the R-12 route, including the high and low side schrader valves (accumulator will come with a new low side). This would be the way to go if you want to keep that 12k miles car all original looking, and don't mind spending more to do it. This is of course the worst time of the year to buy R-12.

https://www.epa.gov/mvac/se...rtification-programs

ASE and Mainstream have the best online certification systems IMO

https://www.ase.com/Tests/cfc.aspx?mcid=lp.gm

https://ww2.epatest.com/epa-609/
theogre MAY 27, 04:52 PM
Plus Most selling "R-12" on Ebay and elsewhere are sell crap known as "Freeze-12" and other names containing a mix of refrigerants including Propane, Butane, and others that have problems and Illegal for Vehicle use.

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Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

The Ogre's Fiero Cave

sledcaddie MAY 27, 06:08 PM
Thanks for all your responses! I will have the system sucked down to check for leaks first. Of course, i don't have that kind of expensive equipment. On a previous 88, when the compressor seized, there was some company that sold a kit to convert to R134, along with a new compressor. I'll have to check my records. I've read several responses on this forum over the years that recommended sticking with R12. I'll balance all my options. First, I have to replace the 32 year old Goodyear Eagle-4's...this Friday! They're not weather-checked, but I don't trust them.
sledcaddie MAY 27, 06:11 PM
[QUOTE]Originally posted by RWDPLZ:

" Accumulator is a must due to the desiccant, and orifice tube is also cheap insurance. "

Why is the accumulator a "must"?
RWDPLZ MAY 27, 07:15 PM
It contains a bag of water/moisture absorbing desiccant. The purpose is to absorb moisture in the system. Once the system has been opened (or just due to age), the desiccant becomes saturated, and the bag containing it may actually rupture and spread throughout the system, as well as no longer absorbing water, that can combine with the hygroscopic refrigerant oil, cause corrosion, freezing in the evaporator or orifice tube, etc.

See also

https://macsworldwide.wordp...ur-mobile-ac-system/

https://www.flowdry.com/new...itioning-systems.htm

Not Fiero but almost identical:



This is why the accumulator comes with plugs on the inlet and outlet. You want to add oil and install it in the car as the last step before you draw a vacuum on the system to check for leaks and add refrigerant.
sledcaddie MAY 27, 08:12 PM
Thanks, RWDPLZ. That was very informative. I've worked on cars my whole life, and never knew what was inside those, and what their purpose is.