so if you are going from r-12 to r134a you need to do a complete evac Freon, oil the works and get the r134 high and low side pieces

and check if the compressor works

 

the freon evac'd itself about 8 years ago via a leak.

 

I have a massive leak in mine. I just bought the truck. It is a 1990 sr5 v6. How do I even tell if it is r134a vs r12? I am more of a drivetrain junky. Never messed with a/c.

 

One of the under hood stickers tells you what the A/C system uses.
I can't remember the change over year.

The leak has to be located and fixed, then a vacuum pulled on the system to get all the crap and and to verify no leaks.
Then add R134 and some PAG oil.
Yo have to change the HI/LOW side fittings as noted above.

 

One of the under hood stickers tells you what the A/C system uses.
I can't remember the change over year.

The leak has to be located and fixed, then a vacuum pulled on the system to get all the crap and and to verify no leaks.
Then add R134 and some PAG oil.
Yo have to change the HI/LOW side fittings as noted above.

93 has 134a

 

If unsure if it's been converted, look at the fittings. R12 uses small screw-on fittings. R134 looks like a short fat mutated air compresser quick disconnect.

You'll probably have to change the compresser. Sitting for 8 years, exposed to atmospheric moisture and oxygen, nothing to circulate lube. moisture reacting with residual refrigerant to make flouric acid (IIRC...one of the nastier ones anyway)

If you want to be cheap though (and risk wasting the first refrigerant charge) just replace the R/D, pull a vacuum, then fill it up and see if it works.

 

i was going to just fill it with 134a and some leak detector and see what works and what doesn't and also see if i can find the leak. if i do replace the R/D how do i pull vacuum on the system?

 

i found the leak, it was the valve on the high side. i just replaced the valve stem on both the high side and low side valves, put about 2.5 cans of R134a in there and it's working great and blowing cold! i didn't change or replace anything else. a/c hasn't been used in 8 years but everything was still functioning.

 

Now we start betting on how long it works :clap:

You use a vacuum pump meant for AC work. If you don't vacuum the air and moisture out before putting refrigerant in, the nitrogen won't do much but reduce efficiency. the moisture, oxygen, and refrigerant will react to make a very strong acid (hydroflouric?) which will usually kill the compresser first then everything else.

 

Now we start betting on how long it works :clap:


You use a vacuum pump meant for AC work. If you don't vacuum the air and moisture out before putting refrigerant in, the nitrogen won't do much but reduce efficiency. the moisture, oxygen, and refrigerant will react to make a very strong acid (hydroflouric?) which will usually kill the compresser first then everything else.

i appreciate the words of encouragement. :clap:

i guess we shall see and i will keep everyone updated. that being said, if it does go out again and i have to replace parts that are over 20 years old it doesn't seem like i'm losing anything. if my a/c gets me through the summer i'm happy and i can replace everything over the winter at my leisure, i needed a/c now and i got it and i didn't have to spend any money, i'd say that's a win.

 

Is the A/C still working? Lol!

 

My 94 had R12 and was had no pressure when I got it. Replaced a few O-Rings
and had a pro install 134A.
Been working for 3 years!