How to check the a/c pressure switch

[Cool81z28]

My a/c compressor lately has occaisionally not been kicking on. I can go under the hood and tap on the pressure switch and jiggle the wires and then it will kick on. When it kicks on it blows nice and cold like it should.

Its got 42 lbs of pressure when it kicks on so I know its not low on freon.

I replaced the dryer and expansion valve about 6 months ago so I'm pretty sure that is not the problem.

I would like to test the pressure switch with a multimeter to see if it is the problem or maybe in the wiring.

My question is should there continuity through the switch or not when the system is properly pressurized?

[Rob Bell]

Re: How to check the a/c pressure switch

Since it's kicking on when you tap it, it's most likely the switch. You can also jump the connectors on the wiring harness and if the system runs, then you know it's the switch. This must mean that the switch should have continuity when pressurized.

[Cool81z28]

Re: How to check the a/c pressure switch

That make sense. Thanks.

[kristen]

Re: How to check the a/c pressure switch

just had the same problem in my malibu. it ended up that the blower motor was crapping out on me.

[Cool81z28]

Re: How to check the a/c pressure switch

just had the same problem in my malibu. it ended up that the blower motor was crapping out on me.

If its not my pressure switch I'll check that. How does the blower motor affect the compressor not engaging though? I didn't think they would be related.