nakol128

So I have a 1991 F150 that is still has an a/c that runs off r12. I bought a retrofit and recharge kit, but i was wondering if i need to vacuum my system. I know that if r134a is mixed with r12 it can completely destroy my whole system. The reason I ask is because I read somewhere that if your a/c doesn't cool at all there isn't any r12 left at all. (and mine doesn't cool at all.)
Also, if I do need to vacuum my system, any ideas where I can get a vacuum pump? And do I need a specific one? How expensive are they? Oh,...someone told me I can rent vacuum pumps for free from auto zone. Is that true?

skizriz

If there isn't any R-12 left at all, that means it leaked out somewhere. The R-134A will also leak out.

I always advise taking it to somebody that is qualified to work on AC. As you stated, do it wrong and you wreck your system. Then your $200 repair turns into a $1200 repair.

2010FX4F150GILROY

It can be worse than that, you can have R12 left in the system. The system has a cutoff point that says if it does not have a given pressure it will not lock the compressor. However it still will have some R12 and mixing the two is bad for your system They sell leak detector you can charge your system with it and how bad its leaking.

9F150Lariat4XOwner

I had a retrofit kit that I used on an 02 camry. The manufacturer of the kit said vacuum. I had no cooling, so I thot it all leaked out, but no. I didn't vacuum the system and Locked the compressor up because of it. Your truck, but my advice is to have it vacuumed.

bajaman

I've done 5 different cars, converting them to R134a over the years. As others said...it is critical to find out WHY the leak occurred in the first place. Once repaired, you can either re-charge the system with the much more efficient but more expensive R12 or....do the conversion. I always replace the dryer, that in my book is a given. You need to find out if your compressor is compatible with R134a, often you'll simply need to drain the oil in it and replace it with R134a compatible oil. Sometimes you DO have to change compressors. I also replace most of the 'O' rings that are easily accessible, though a lot of people adhere to the "if it ain't broke, don't fix it" theory on that. R134a doesn't cool as good as R12, so don't be upset if you see about a 5 degree difference in the coldness of the air coming out.

9F150Lariat4XOwner

Yup, what he said. Much better tech answer than mine. G/L to you.

Just call me Sean

iTrader: (1)

Don't half ***** the a/c or you won't be satisfied with it. It already isn't going to be as efficient since you're using freon it wasn't designed for.

Most likely there is no freon in it because it hasn't worked in years, but you do need to make sure it's empty. Change the accumulator and orifice tube, blow out the lines with compressed air, add oil to the system and make sure the compressor has oil too, vacuuming is a must. If the system hasn't worked in a while then most likely the compressor isn't any good, they are junk brand new (a/c guy told me so ).

Kattumaram

Ford FS10 compressors ran R12 and mineral oil, but will run with R134A and PAG-46 lube oil.
PAG is not compatible with R12 and will not mix with mineral oil used in R12 applications.
PAG may be used in clean systems if the system contains less than 5% residual mineral oil; otherwise, use polyol ester oil of the same weight.

The R134A charge should be 85% of the recommended R12 charge and will produce evaporation temperatures about 3F higher than R12 at the same pressure. R134A is slightly less efficient than R12, but not enough to make any noticeable difference aside from the slightly higher evaporator pressure temperature.

Whatever is done pull a vacuum of at least (-)28inches on the entire system for about an hour to guarantee all moisture is extracted from the system. System leakage can be detected during the pull down.

An excellent vacuum pump can be fashioned from a refrigerator compressor. Fabricate and attach a suitable hose fitting to the suction side of the compressor....it'll pull down to better than (-)28inches. (I have a little 100 watt compressor from a 5 cu.ft. freezer that works like a charm.)

Don't turn the compressor on its side or the internal works will fall out of the vibration damping system and screw up the compressor.

bajaman

lol.....sounds like you know this from experience?

Ryan Jarvis

So I have a 1991 F150 that is still has an a/c that runs off r12. Where do I find a retrofit kit for it to convert it to R-134a.