98 jimmy A/C

The A/C won't work on my 98 jimmy. Automatic controls.
fuses good. jumped pressure switch and compressor clutch engaged. replaced switch. same problem. have pressure. The schrader valve in the accumulator at the low pressure switch leaks, but i don't imagine that should effect the operation. I added some pressure because the manual I have said to test at 50 psi, and the clutch cycled on and off continuously every 5 seconds or so. Plugged orifice?

is it low on fluid

nope

With compressor jumped and running post back you low and high side readings at idle and at 2K.

With a ac recharging gauge set.
Like one of these.
http://www.ackits.com/merchant.mvc?Screen=CTGY&Store_Code=01&Category_Code=DIY

Low side should be close to 30 lbs.
If it is dropping under 25 lbs the switch will cycle or shut off compressor.

As far as the Schrader valve leaking. you can buy a tool to tighten it at Advance Auto for under $5. Looks just like for a tire valve stem, just longer, mabe a slightly different size. That was the only problem with my ;94 p'up. If the valve leaks, you are losing the refrigerant.

I only tested the low side before (somebody had a death kit available), but the swith would shut off at 45psi on the low side. Also, it immediately began to lose pressure rapidly upon the compressor engaging. I'll get a real guage and post back, but as far as the schrader valve goes: it's the valve on the switch, so it only lost coolant when I changed the switch.

Make sure you have a good pressure gauge.

The switch should stay on until the pressure drops down to around 26 lbs on low side.
Then kick off and waits a minute or two until the pressure gets back up around 40-45 to kick back on.
And then stay on until the pressure drops down around 26 again.

A fast cycle is usual low gas charge.