Question about R4 "Pancake" AC compressors

[gmbellew]

How would one go about adjusting a low pressure switch?

pop off the electrical connector to accumulator and there is an adjuster that looks like a slotted screw.

from the 1990 manual (your year may be different)

 

[R Carnella]

I'm convinced any R4 you can buy today is junk and will not last. Sanden is the only real solution.

 

[SirRobyn0]

Well I'm running a retrofitted system with an R4 compressor. It was done before I bought it so who knows what was or wasn't done or how it was done. It works fine.

Use ester oil, not pag, pag won't work with any mineral oil left in the system.
As a general statement it seems to me the biggest thing about retrofits in general that they don't want to cool as well at idle as R12 meaning they need more air flow across the condenser, so if your not already running a serve duty fan clutch now would be a good time to install one.

At the shop we have had good luck with ACDelco new A4 units as well as GM Genuine. IMO up grading the compressor is not worth while.

 

[Rusty Nail]

Yep! That Sanden, that's what I want too. 'tis the right swap to get uh huh.

 

[Vbb199]

You can get a gmt400 low pressure switch for your truck. Just a thought.

Its like a 92 or 92 suburban low pressure switch i think

@Bextreme04 recommended it to me i think.

I did it. It operates at r134a pressures and should fit right into your air dryer.

@CheemsK1500

My bad there, 95 and up would be what you'd need in a gmt400 pressure switch.

My bad.

But someone already chimed in on adjusting it