Terry Bell

I've had this truck since it was brand new, so any problems I've had have been easy to diagnose and repair.. with a 1/4 of a million miles on the dash it's still running strong..

At the moment however I am having an issue with my A/C. It's got a full charge of R-134a and will blow cold.. but ONLY if I jumper the low pressure switch connector and bypass the switch on the accumulator.. if I leave it plugged in, it will only blow cold after the engine heats up and only if im doing city speeds (30-40mph)

But like I said.. if I use some wire or a paper clip and jump the connection on the low pressure plug.. it blows cold all the time

So, New LPS? Or is the problem elsewhere

Bern

Because the clutch engages with the low pressure switch bypassed.
This also means you bypassed the problem.
possible faulty switch.
More likely low refrigerant charge. Was the system pulled down to 29" of vacuum then charged to the correct charge capacity


As the underhood temperature rises so will the temperature in the accumulator.
The hotter the refrigerant gets the higher the pressure will be in the accumulator.
So with the engine and refrigerant heated up the pressure will be high enough to switch on the compressor clutch.