This will be the first summer I have had this truck so I decided to get the A/C straight. Some idiot tried to put a a/c clutch on it before I got it and screwed the snout all up so i bought a new compressor. I put on a new dryer an orfice tube an flushed the system.

I pulled a vacum for an hour or so and it held fine. When i tried to fill it up the first time it would not take but half a can an was freezing up after the orfice. I opened it back up an the orfive tube was nasty with rust. Changed it out and flushed again an put 3 cans in it.

My pressures look good , Low at 20-25 and high at 190 with out side temp 70 an at idle. I can get the temp down to 50 at idle but it seems to warm up when driving 4-5 degrees. This is opposite of how it should work. Am i missing something?

 

Did you put any new oil in the system? it needs to be properly lubbed.

 

yep, pag 40 in compressor an dryer

 

The low pressure figures you posted are very low, you should be reading around 50-55, at least that's how my system was filled at an A/C shop.

 

For r134? I have all ways put A/c systems at 20-25psi an they work great. Thats why I am stumped on this one. I have only worked on R134 systems and those are the correct pressures so I wonder if the pressures are different for r12 to 134 conversion, hmm.

I have read that some poeple run 35-45 but that would mean that I would have to add some an that seems high to me but I will might grab another can an see. What temp does your a/c put out?

 

I can't give you a temp reading right now, might try it in the next days, but my system seems to need an even higher charge.

 

You need to make sure that your compressor is cycling. It has a "deice" switch that kicks the compressor out at about 20* and back in at about 45*. This eliminates your chances of the evaporator freezing up. Check it.

Next your pressures seem to be a little low, but not bad. Possibly the 70* ambient air temp. I like to see in the 220psi range for the high side. One thing to check is start it up, let it run and then shut the engine off, with gauges hooked up and watch the pressures. The high shouldslowly fall and the low should slowly rise. After a few minutes they should be equalized. If they take very long to equalize, then you have a restriction in the system somewhere, better find it.

Other than that, start there and see what it leads to. If your orifice tube was rusty that doesn't sound good. Another option is change the orifice tube to one with a slightly smaller orifice, that will cool better and faster.

The main difference in freon is the R12 is a larger molecule than the R134 therefore the R12 can carry heat better, or faster, making it more efficient. The smaller molecule R134 moves through the system faster and makes it harder to shed the heat, due to spending less time in the condenser. A smaller orifice will enable the freon to cool longer in the condenser and let it shed heat. All things to consder good luck.

 

What should be the low pressure I should have Warhorse?.

 

I am using the red orfice tube. i think red is for 134 an the blue was r12.. I flushed the system an I think it just knocked some rust loose from the system being open for a couple of months an thats why the 1st orfice tube was clogged. Thanks