AC pressure switch

NOMADW8

MEMBER
1994 FORD F-250
5.0L
V8
2WD
AUTOMATIC
132,000 MILES

AC compressor clutch does not engage when AC is switched on from inside truck.

I pulled electric supply wire plug off of the AC pressure switch and short circuited the plug with a piece of wire. Compressor clutch engaged and spun.

I do not have an AC pressure gauge.

So it seems either the system pressure is too low to activate the pressure switch or I have a bad pressure switch.

How can I test the pressure switch in order to isolate my problem?

Thanks.

Terry

1 Reply

ASEMASTER6371

MECHANIC
52,797 POSTS

Good afternoon.

You are right on point with the checking.

It is a normally open switch and needs pressure to close the switch. It must have a minimum of 20 lbs of pressure in the AC system for it to close.

Use an ohmeter to check continuity or the switch. It should read OL at rest. Then apply 20 lbs to the bottom of the switch and retest. If it stays OL then it is bad. If it reads 0 then it is working and you have a AC system issue.

Roy

https://www.2carpros.com/articles/car-air-conditioner-not-working-or-is-weak

https://www.2carpros.com/articles/air-conditioner-how-to-add-freon