Ok, It's 97 degrees with 90% humidity here in the SE and I can't take it any more with out the A/C in city traffic. I have a 89 F-150 which has been a complete restoration project. Body work, paint, new trans, alot of engine work but have not fixed the A/C and it hasn't worked for at least 10 years. Would like to convert to 134a but from what I have read it can be a real problem if not done correctly. Sounds as if the whole system needs to be replaced when you go that route. The original problem was the evaporator leaked. So would it be better to replace the evaporator and possibly the compressor and recharge with the R12? And does any one know how difficult it is to get to the evaporator. Can it be removed from the fire wall side or through the dash side? Thanks for any opinion on this matter.

 

the whole system doesnt need to be changed. you can just retrofit the system...read up on it.

 

If the system has been open for that amount of time everything that is metal has now been subjected to moisture which creates corrosion. Add in the fact the hoses are over 20 years old. I would highly suggest new lines, compressor, receiver/drier, evaporator, condenser, and orifice tube. Just like you said, a new system.

You could piece meal it with a new evaporator, receiver/drier and orifice tube but you really run the risk of having those hoses leak like a sieve or blow out completely. With all new components you can charge with whichever refrigerant you choose.

BTW... the evaporator should come out the firewall side. It's not really that bad.

 

All I had to do on my 87' was evacuate, replace the seals, refill to specs. Each truck may end up being a slightly or vastly different story.

 

I agree each situation is unique. My suggestion for a complete rebuild is based on the theory of "Do it once, do it right". The OP has already put a lot of time and money into their truck. Why not finish it with an A/C system that will work for another 20 years?

 

I could not agree more!

 

If you are replacing the evap core and the compressor, the only other thing you need for it to last a long time is the manifold hose assy. R134a has smaller molecules than R12 and will leak thru the hoses your truck came with, even if they were new, but since they are so old, it's gonna be worse. I did this conversion on my '91 about 3 years ago and it is still working and I have not had to add any R134a. I replaced the compressor and the manifold hose assy and the drier and then flushed the other lines.

Now, one other thing I should have done to make it totally perfect is to replace the condensor with a newer one made for R134a. You need more condensor area for R134a and I cheaped out and kept mine in place, thinking I was gonna add an electric fan to make up the diff. Well, I never did add that fan, so at idle, my air goes up to about 55 degrees. Otherwise, the system works great as is.

I'll get around to it one day if it ever needs to be refilled, but so far, it is staying full.

 

I think if you really tried, you could in fact, agree more!

 

Removing the evaporator out from the enginge compartment side is a cakewalk, if need be.

 

Good point on the condenser. It is well known when converting from R-12 to R-134a the condenser becomes the weak link. The OP has stated they live in the southeast with high temperatures and humidity it will quickly prove once again the shortfall of this conversion without considering the need of a proper condenser.

Several options I see here. First is sticking with R-12. It's still available, the price has come down from the first initial shock when production was ceased in the US. Second is consider a drop-in replacement such as Auto Forst, Freeze 12, etc. They all work very well. Third if you really want to go with R-134a look into a custom parallel flow condenser. They are readily available and would make the R-134a conversion a much better performer.

 

Thanks for the replies. I believe i'll keep the truck a while so im going to replace the whole thing and go to 134A and be done with it. The truck will end up being passed through 3 generations of the same family. Maybe more. Again appreciate all the good responses.

 

how many 12 oz cans of oil and freeze 12 would be required to fill a completely discharged a/c system on a '93 f250?
id like to find out soon,as iv got an order on amazon,that i can still add to,likely only within another hr.
thanks!

 

Freeze 12 is lighter than R-12. The documentation I see states to charge to ~90% of the R-12 rating. For your '93 that would be 44 oz. X 90%= ~40 oz. Oil charge is around 7 oz. total. If you are not changing the compressor, you should not need to add oil. If you are unsure of the amount of oil already there it would be wise to disconnect the compressor, then drain the oil out to measure it.

 

4 12 oz cans,and 1 can of oil is what i need to order then.thanks man!

 

Anytime