I picked up a 1990 F250 460/E4OD with 70k miles on it about 6 months ago. When I bought it, the AC wasn't working. I put a can of R134 in it, and it blew cold for a month. I'm assuming it leaked out. Put in another can and it blew cold for about two weeks. The last can lasted 3 days. So, I'm ready to fix it. I put in a can with the UV dye in it and I still can't find the leak.

I'm planning on replacing the orifice tube and accumulator/dryer.

Should I replace all the O-rings? Replace some of the lines? Which are the most common to fail?

Should I try with the can of UV dye one more time?

I'm thinking of ordering the parts from rockauto. Is there a better place to get them?

thanks
Austin

 

Your truck was originally an R12 system, so if it hasn't been "converted" for R134, it's a good time to do it.

Chances are, it's never been worked on, so O-rings are probably leaking. Hoses for R134 are of a barrier type, to prevent leakage of the smaller-molecule R134.

If you want a 100% guaranteed correct fix, you should replace everything. Compressor, Accumulator, orifice tube, hoses, condenser, and evaporator. Sounds like a lot, but it's probably a total parts cost of $400. To me, it's worth it to have reliable AC.

At the very least, replace hoses (which come with new O-rings), accumulator and orifice tube. Flush the condenser and evaporator. Remove the compressor, and empty it, but do NOT flush it. At this point, you can pour 4 oz. of Ester oil into the compressor, and 4 oz. into the accumulator. Assemble everything, pull a vacuum for at least an hour, and make sure the system holds a vacuum. If it holds vacuum, there's no leaks. If it doesn't hold vacuum, then you've got more leak checking to do.

Best way I've found to check for leaks is to partially fill the system, and use a refrigerant leak detector (kinda like a sniffer).

There's no such thing as a common component to fail, really.

*edit, forgot about parts sourcing*

I just recently bought a compressor, accumulator, lines, and orifice tube from an eBay seller, techchoiceparts. Although the first compressor the sent me was defective, they honored the warranty, and I was very satisfied with their service and parts.

 

Thanks Bob,

I just placed an order at rockauto and get everything but the compressor. They only had two different lines. One was the line set that attaches to the back of the compressor and one was what they were calling the liquid line. I don't know if that is all the lines or not. I ordered a new condenser as well. That should give me the increased area to work well with the R134. I also got a set of Orings, the red Orifice tube, and the dryer/accumulator. I will try and find 8oz of ester oil locally. Do you think they have it at oreilleys or autozone?

I will report on how well it turns out. I already have a vacume pump and a line set from when I installed a custom AC kit on my 1970 F100.

thanks
Austin

 

Yeah any parts store should have compressor lube.

 

Yep, those are all the lines. And as mentioned, yes, they'll have Ester at any parts store.

 

Just finished installing all my new AC stuff, and realized I was wrong about the amount of oil. On my underhood label it states 11 oz. 8 oz. was for another car I worked on. Sorry!

To be sure of how much you need, check your underhood label, or a service manual.

 

How do you know that the compressor seals aren't leaking? UV Dye needs a black light to see where the leak is.

Craig

 

^^ This. You need to use a UV light and yellow glasses to have any chance at finding the small leaks. Took me an hour to find the smallest trace of dye in the evaporator drain of a Grand Cherokee. Condensers and evaporators are the most "common" things to leak, while compressors are the most common failure item. Do remember that you need to pull the system into a vacuum and let it sit for a while to remove all the moisture and air. Moisture is the main enemy of A/C systems since it causes rapid corrosion. Air will decrease the efficiency and raise system pressures.

 

Your correct but I have used a black light & it would show up but easier your way. The other thing is after you put about 4 bottles of UV dye in if the leak is as bad as he says 3 days green will start showing up. But putting R134 in an R12 system may of damaged the compressor because mineral oil doesn't travel with synthetic R134. Just depends if there was enough oil in the compressor to keep it lubed.

Craig

 

Thanks for the help guys. You are correct in that I'm not positive it isn't the compressor seals leaking. Maybe I will throw one more can of R134 w/ dye in there. yes, last time I did use a black lite and the yellow glasses that come with the kit. I didn't find anything. Today I'm going to be driving a bunch in hot weather with the kids in the truck, so another can won't hurt....maybe. My parts are supposed to show up Saturday.

My only hope is that it ISN"T the evaporator because besides the compressor, that is the only part that isn't getting changed.

Thanks
Austin

 

So, about 7.5 years later, did you solve the leak problem by changing out the parts? Did you need to change the Evaporator? How long was the process and was it difficult. I am about to change my components out too. Start new and things can only get better.....
PJ