Ok, I replaced my compressor on my 1988 F-150, 400,000+ miles, this time I changed comp. evap. condencer, orfice tube, and dryer with compressor, pulled vacum then filled with 134. Pressure is fine, but does not cool good when at idle, going down the road it is fine, but if I stop it is not cool. While stopped I can rev up the motor a little and it will cool, it is a new compressor not rebuilt, anyone have this problem?

 

Sounds like yiou have an air flow problem.. Your fan clutch in good shape?

 

Yea new also, I am thinking the compressors on newer trucks may pump faster, with a smaller pulley, or more CFM to move freon faster, what yall think.

 

Hey any thoughts?

 

it sounds like your fan aint moving fas enough at idle, that usually happens if you have a diesel truck! have you considered putting an electric fan?

 

R134A operates at a higher pressure than R12. Newer vehicles that use R134A were designed with a larger condenser to get rid of the extra heat generated by the higher operating pressure.

Some vehicles retrofit to R134a with acceptable cooling temperatures. Other vehicles don't cool as well as R12.

Take the open book test at EPA Certification by Mainstream Engineering
Then you can purchase R12 legally.

 

Yep - your system was designed to work with R12. When you converted it without fully understanding the implications, you shouldn't be surprised when it doesn't work as well as it did before.

 

I would add an electric pusher fan up front and wire it to run
when the comp. is active

 

You said you replaced your condensor, did you put one in that was for a 1988 truck (i.e. R12) or for a 1994 truck (i.e. R134a)? Sounds like you put in another R12 condensor.

The R12 condensor does not have enough area for R134a use and it will perform just as you describe. Mine does the same, I converted to R134a and cheaped out on the condensor thinking I would just add an electric fan set to run with the a/c compressor as mhg suggests. I just haven't gotten around to it yet.

So, you either need to replace the condensor again with one for an R134a truck (1994-96) or add an electric fan that is powered when the compressor is on. If you replace the condensor you will need to also replace the liquid line as your existing hose will not attach to the R134a condensor.

 

Thanks for all the replys, one more question, how about too much feon, I have heard if there is a over charge it will not cool as good, anybody heard this? Oh, I ran water on the condenser to see if that would help still not cooling at idle.

 

An overcharge will cause reduced cooling at all speeds. It is better to be undercharged than overcharged.

 

Hey, thanks again for all the help, I'll let yall no what I find.