AC IS HAUNTING ME

[KennedyHill]

I am trying to figure out the a/c on my 86 C10. I bought the truck in Alabama and drove it 8 hours to Louisiana with the ac running, but it was not cooling very well, but was running. Two days later it locked up. After evacuating the system, cleaning out all the lines, evaporator, and condenser, I replaced with new compressor. Charged system with 51 oz of R134 and added 8oz of oil (conversion had already been made from R12) (I found the 51 oz number from another thread, so I went with it).

System never cooled well, although it was too cold outside for me to get a good test. I was waiting for warmer weather to adjust. While driving the other day, the brand new compressor locked up! ‍

one thing I noticed while charging the system, the compressor was engaged all the time; even before I charged it. Why? Doesn’t it have a switch to operate this function?

I checked the high pressure switch. When unplugged compressor clutch disengaged; plug it in it engages again.

What about a thematic switch (I’m not sure what it’s called), but isn’t there supposed to be a switch that tells the compressor “I’m cold enough” and it switches off? I’m referring to the switch that has a wire that pokes into the evaporator. I can’t find it on my unit.

I just don’t know what to do. Any help would be welcomed and appreciated. Thanks.

 

[KennedyHill]

The name of the part I’m looking for is Evaporator Temperature Sensor; I think. Does my 86 have come with one? I see where the mounting position for the switch is on the evaporator housing, but there is no hole for the probe and no switch.

 

[fast 99]

Should have a low pressure switch on or near the dryer. 51oz sounds like too much. If it is a PU [not a dual system suburban] my specs show 3 1/4 lbs for R12 or 52 oz. 51oz is way too much refrigerant converted to 134A. Should be filled to 80% or 41 oz.

Did the directions on the compressor say it was dry? If it was your close on oil however if already filled 8 oz is probably too much. The directions should say one way or the other and ask that it be drained before installation. Otherwise, you won't know how much oil is in the system. Too much oil will reduce cooling.