I've searched a lot of forums and can't seem to find a clear answer on this.
I converted my 1992 f150 to r134 from r12. As you probably already know it doesn't cool very well when it's hot out. I replaced just about everything except the condenser and evap.

Does anyone recommend changing the condenser to something larger? I believe I read somewhere that 94-95 f150s have a condenser better suited for r134?

 

doesnt matter. I'll bet you put too much freon in the system. R134 works on the lower pressure. you need just enough to pacify the low pressure switch at 2,000 rpm.

the more low side pressure you have the hotter the system runs.

I've heard that the low pressure switch for a 134 system is lower than a r12. although I've converted many r12 systems I;ve never changed the low pressure switch.

Only thing I;ve ever changed in the dryer and only one time. Just make 100% sure you're not adding any Freon W/OIL..... too much oil and the system wont get cold either. as the oil cannot dissipate the heat. you ONLY need what oil is in the compressor and if you put a new compressor on they are pre-filled with oil and NO additional oil is necessary.

How i charge a 134 system. i rig a light in the cab to the low side switch so it is on when the compressor is engaged. I try to fill the compressor in the early morning hours around 6 am but you can do it any time of day and preferably in a shaded area.

then from a near empty stand point add a can with the can upside down (valve on bottom) add until the compressor stays on then raise the rpm to 2,000-2,500 rpm then add until it stays on.

then drive the vehicle as normal and watch the light you rigged up and see if the compressor cycles. use a temp gauge in the vent to watch temps out the vents.

at 60 mph the compressor shouldnt cycle while maintaining speed. it may however cycle if taking off from a light and the rpm gets up but should hold steady once at highway speeds.

you will find a "sweet" spot where once you get the perfect fill it will get pretty cold and even at idle it will hold the temp. one side or the other it may not work at optimum.

I fill all of mine this way and I have had NO issue getting an AC unit down to 32°-28° with normal driving and years of use on worn components....

 

Thanks for the detailed info. I think May have added to much r134 in my attempt to make it "colder." I'm going to try it again but do exactly as you described above. I'll post back my results to help future converters. I may ask you some questions as I go. ;-)

Btw. This forum has been invaluable to me in working on my truck!

Thanks again for your help.

 

Have you tried flushing out the condenser?