Georgia Fiero Club Forum
All Things Fiero => Tech Tips, Tech Questions => Topic started by: NoMad on May 02, 2019, 04:11:07 pm
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So my Alaskan blood is still running a bit too warm and it isn't even summer yet :o !
So the AC in the formula fastback is not cold at all and so it is really a major issue I need to tackle.
With that in mind, I have read hours of PFF threads all saying to do different levels of equipment replacement or not for 134a conversion. Others swear R10 is still viable. All of it is leaving my head spinning.
Has anyone local done the repair/swap to 134a route? Anyone have a handle on a shop with R10? Do I really need to gut and rebuild the whole system? Is less better? I know there are supporters of all methods but hoping someone local can offer some insight.
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Actually, the old stuff is R12. But you can convert to R134a yourself, and not have to mess with R12, which only authorized repair places can work with. At the minimum, you will need conversion fittings, a new accumulator and orifice tube, 100-weight ester oil, and a vacuum pump (assuming that your compressor is OK). A properly converted system will give you plenty of cold. I have a vacuum pump to loan out to paid members.
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If you are replacing a compressor, most require a new accumulator and orifice tube to activate your warranty. My compressor from Four Seasons had paperwork that specified 150 PAG. Oddly, instructions said to not use PAG to lubricate the seals and O-rings because it causes corrosion. I have a bottle of Nylog Blue that is used by HVAC people, both automotive and commercial/residential, for lubing seals and O-rings. It doesn't dry out like other lubricants and it prevents leaks. A 30ml bottle will lubricate every Fiero on the road today. It's available if you want it.
I may be telling you something you already know, but the whole system needs to be evacuated of all the old refrigerant and oil. The conversion for a Fiero uses exactly 36 oz. (3 Cans) of R134a). Four oz. should go into the accumulator and 4 oz. into the compressor. My compressor said it had 3 oz. in it when it arrived, but we drained it and added 4 oz. to be sure. With the system on MAX, the temperature should drop 40* below outside temp.
On and Off pressures are different for R12 and R134a. The R12 cycle switch on the accumulator can be adjusted for the R134a but it's much easier and relatively cheap to just buy a cycle switch for R134a and you know it's set properly. No guesswork. Or grab one off a junk yard car.
Don't be tempted to get one of the variable or Smart VOV orifice tubes. They're expensive compared to a standard tube. Mine caused the system to overpressure, then the installer had to rip the tube apart to get it out because it lodged in the hose.
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Charlie, I think you left out the part about 8 oz of oil......
Yes, I have converted mine over. There is 1 oring near the front that is amost impossible to get to without dusmantling almost the entire front end. My car I left it as it was.
If I remember correctly, you need 80% of the r12 charge (40 oz) for r134a which works out to 32 oz r134a, a bit less than 3 cans. I used a 40# bottle and a scale.
I got a new compressor through RockAuto and the paperwork said for the warrenty to be in effect proof of purchase of AC flush must be provided with any claims. Flushing the lines isnt too bad with a pressure can and compressed air. Also, a 15mm stubby wrench makes removing the compressor much easier.
I think took me about 4-5 hours total. Please keep in mind that I am not a professional mechanic, nor do I play one on TV
Scott
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I included it above. 4 oz. in the compressor and 4 oz. in the accumulator.
I had frequently heard that 30 to 32 oz. R134a was the proper amount, too. Somewhere I found a capacities chart for the Fiero and it listed it as being something like 45 oz. of R12. RWDPLZ is my go-to guy for AC info and he also told me that it was 36 oz. for R134a. My installer used gauges and put the 32 oz. in that I told him, but it didn't cool well, so I put the rest in and it did work better.
I guess it's best to use the gauges if you have them, along with a thermometer stuck into the center vents.