A/C Clutch not turning
 

On my 2002 SC2 3 door the A/C clutch is not turning. There is no power (12v) to the compressor connector. I've checked under hood and interior fuses and swapped out the relay.
I have R134a with gauge and it was low and bumped it up to full. The fan works fine and the A/C interior light is on. I could jump 12v to compressor as a quick test but decided to replace the A/C sensor switch first. But I can't find the right part - eeech - and again I could use some help.

I'm searching "A/C pressure sensor switch" with a few variations.
Advance Auto returns "GM Genuine Parts Air Conditioning Clutch Cycling Switch - Part # 15-5720. Does Not Fit your 2002 Saturn SC Series"
Auto Zone has "Santech A/C Switch MT1618". This looks right but have no idea if it fits my car.
RockAuto - has no part that comes up

Please help all of us cut through this fog with the right part, Thanks!!
Why is something which should be so easy so difficult?

I'm not an a/c guy, but I THINK there's two different switches. You have a low pressure switch and a high pressure switch. I THINK. Maybe you need to be specific on one or the other?

For the first and second generation S cars, the high pressure and low pressure switch are combined in a single switch that sits in line in one of the refrigerant lines towards the front of the car.

Do you have 12 volts from one of the leads to chassis ground? The switch basically acts as a pass through so if the pressure is too high or the pressure is too low the switch goes open and the 12 volts no longer continues on to the compressor.

I doubt that would have changed this.

Haven't heard of a compressor cycling switch for an S car before so I don't think that's it. Should be labeled as a high pressure low pressure cut off switch. I will do some poking around and let you know what I find.

In the meantime, please ensure that you have 12 volts at one or the other connector wires because if you don't, the issue is electrical and has nothing to do with the switch in which case there's no need to chase one. Could be a broken wire, could be a fuse Not making good contact with the terminals because of light corrosion, could be melted contacts underneath the relay on the fuse box where it plugs in and the wire attaches. All kinds of great stuff that is not obvious. Please check that now so I don't go on a wild goose chase for nothing.

Thank you

And what is the system pressure? The low pressure switch will trip around 25 to 30. I've never had the high pressure switch trip so I don't know where that goes but the system takes two with a small cans to fill it. If you've had any more than that it's overcharged but I doubt that is the issue here if it was empty.

Derf, I disconnected the clamp to the pressure switch. There are 2 pins - dark green and light green. With the A/C on there is 12+V on the light green wire. There is no voltage on the connector to the compressor. The R134 is at 35 lbs. - in the Green on the gauge.

I'd like to change that pressure sensor switch but not sure of the right part.
Can I jump 12v directly to the compressor to see if the clutch turns?

As always, thanks for the assist!

Sure you can jump it. I believe a static of 35 is low enough to trip the low pressure switch. Static when off should roughly be the same as the ambient temperature.so I would say at least 50. That is high enough to not trip the switch. A fully charged s car a c system should, when operating properly, show 220/30 ish.

OK.....made a jumper and put 12v to the compressor. The clutch engaged just fine. So, if I have 12v into the pressure switch and no V out to the compressor but a 12v jumper spins the clutch I would say replace the pressure sensor switch.

But I don't know the part. Please help.
Advance Auto has "GM Genuine Parts Air Conditioning Clutch Cycling Switch - Part # 15-5720. But is says that it "Does Not Fit your 2002 Saturn SC Series"
Auto Zone has "Santech A/C Switch MT1618". This looks right but have no idea if it fits my car.
RockAuto - has no part that comes up

Derf I hate to ask you to run this down but I'm running out of options. Any suggestions would be helpful As always thanks for the assist.

Or your switch is fine and the system is not sufficiently charged.


I'm assuming that you jumped the connector to that sensor in order to turn on the compressor to add refrigerant.

No, you haven't added any refrigerant because you didn't know whether or not the clutch engaged until just now.

So before you change the switch you can't identify, add some refrigerant to the system. You may see yourself a whole mess of trouble because it may work fine and just be low.

I'm not trying to be difficult, I'm trying to save you a lot of work You may not need to do.

I have looked into the parts somewhat I need appears in 2002 they added a device that periodically cycles the compressor on and off probably to save gas and improve gas mileage. I'm willing to become familiar with this but only if I have to. Please post a picture of the device you believe is the high low pressure switch. Not just from the top but also from at least one side so that I can see the shape of the outside of it, and a bit of a wider shot so I can see where it is in the entire refrigerant system. Thanks.

Ok will take pics tomorrow, it's getting dark. I'm using the A/C Pro R134 with gauge and it says charged in the green 35-40 lbs. I jumped 12v from the battery directly to the compressor briefly - the clutch spun lightning fast.
To me it looks like a real easy job to swap that switch and just add some refridge. If it doesn't fix it oh well I know that's not the problem but it sure looks like it.
Anyway I'll send pics tomorrow - Thanks for your time Derf.

.

The system needs to read 35-40 with the compressor running.

Thank you Andy.

​​​​​​See post 5.