MPClark did pass the time by typing:
> Alright, I went back to check all of that. After letting the engine and
> A/C run for several minutes, I checked the pressure to be just about
> 40. Then I felt the lines: the two going into the cab are slightly
> warm, the one going into the compressor is also slightly warm, and the
> line coming out of the compressor is too hot to touch. It's confusing
> me because whether there is a leak or not, the pressure is where is
> should be, so low pressure shouldn't be a problem I would think.

The compressor output line will always be hot. The return line from
the condenser (little radiator in front of your radiator) will be cooler.
That line runs back to the accumulator/expansion valve and after that should
be cold, that runs into the cab where it goes through another coil called
the evaporator, then back into the engine bay and to the compressor.

If you grasp the line going from the accumulator into the cab it should
be darn cold/freezing. The line coming out of the cab to the compressor
should also be cold (nearly as cold as the line going in, but not quite)

When checking pressure or filling you need to have the compressor
running all the time, you do that by jumpering the lowside cutout
harness with a bit of wire.

40psi is "normal" for about 75deg outside temp.

General charge chart.
F Lowside psi
65 25-35
70 35-40
75 35-45
80 40-50
85 45-55
90 50-55
100 50-55
105 50-55 (this is where r134a peters out)

The shops measure from the high side.. BE CAREFUL,
high side is HIGH.

F Highside psi
60 120-220
70 140-240
80 170-260
90 200-300
100 230-340
110 270-390

Your description tells me it's low on gas. But don't add a whole can.
only add a bit at a time till the system starts cooling down.

One of these helps for the low side work
http://tinyurl.com/7fsmc


--
DougW