coolant temp sensor

[meandmit]

I was checking to see why my a/c doesn't work, (new purchase, 1995 MM) it seems the compressor clutch isn't engaging when you push the switch, on following the schematics I noticed the coolant temp switch is included in it's path and on my switch it's contacts are gone (gutted) and the wire tie wrapped out of the way. Isn't this switch for the fuel injection and not the a/c? I'm confused.

[meandmit]

36053606

[crvtec90]

The temp sensor for the computer is on the top of the thermostat housing. That broken one is on the side.

Its either a normally closed switch or normally open switch. Its job is to stop current to the clutch if the engine temp gets too high. That being said, does the connector have a jumper wire in it ? You might try jumping the harness side connector and see if the clutch comes on

Is there power going to the clutch ?

You sure its fully charged? There are also pressure switches that stop compressor operation if the refrigerant charge is too low.

If you unplug the compressor clutch you can check to see if it even works at all by running a jumper wire from the battery.

[meandmit]

no power to clutch so checked fuse first, then started at dash switch, cleaned with contact cleaner it was hit or miss, then checked diagram and followed wires to temp switch, that's as far as I got to this point, just wanted to check how it came into play with the a/c. So the switch I have in the picture is not for the fuel injection just the a/c. Car runs great...The second picture has the white connector that I assumed connected to that broken switch, it's 2 prong 2 wire, it's just below the radiator water bottle.

[meandmit]

checked for freon with gauges 100 psi each side, then hot wired compressor to battery, still no go

[DroppedMitsu]

If you hot wired the compressor and it didnt turn on then the comp is done. And 100psi is too much on the low side , should be around 30 or so

[meandmit]

so I guess it's time for a compressor, dryer & orifice tube...anything else....time for some side jobs

[camoit]

Before you swap out the compressor, did you get it to engage? If it is not running then the PSI will be the same on each side. Just remember never to try to charge an AC system from the high side when it's running. It will explode the can. Also never slug the compressor with liquid on the low side when charging. Only vapor can go into the low side. The only time it's OK to charge with liquid is when filling an empty system under a vacuum. Then it's done on the high side with the system off. For a quick refresher please see the manual section under UTI training, look for transport AC. It's all the same just bigger.It's better to be safe then sorry.
If the clutch won't engage when jumping a hot wire directly to the clutch wire then you need to swap out the clutch, not the hole compressor. You say it has pressure that means it's not leaking. Get it spinning first then we can work up from there. Then you can see how it's working by the psi on the high and low side. Get a clutch kit and a puller for it.

[meandmit]

good points, where would one find just the clutch (used) I only see compressors offered?

[camoit]

Used? well pick and pull if your lucky. The clutch won't be that much. The electro magnet is what goes out first. Normally. Try pep boys or some place like that. I can't see it being more then 40 bucks total. They fit about 100 different applications.

[meandmit]

The reason I said used was because no one, and I mean no one offers a compressor clutch, the lowest I found on a compressor was RockAuto @ $285.79. I checked the auto parts web sites, googled it, yahoo'ed it etc. natta...

[camoit]

It's out there, you just need to find a place that can order it. I found a site but it's out of the country. I'll look around a bit and let you know. I bet someone like polar ac can find one. http://www.polarbear-air.com/

Is it a round compressor or a square one? R4 or or York.

OH ya another test, not running. Is to put 12 volts to it and push the flex plate of the clutch and see if it sticks. Also you can use a volt home meter to see if it has an open circuit. If you push it and it wants to engage then you need to re-shim the clutch. AKA put in a thinner spacer shim .

[meandmit]

The compressor is round, it's a Mitsubishi model # MSC90C. I'll do that test on the clutch and let you know what I find out. thanks

[DroppedMitsu]

Was looking in the manual and the top sensor on the thermostat housing is for the a/c. The one broken on your manifold is the temp sensor for the ecu and t bttom one is for the gauge.

[camoit]

Called polar bear and,,, bad news. the compressors for ALL MM trucks using the round style compressor are going to be Re-manufacture only. If you have the square York type parts are available but the other ones, the compressors are going the way of the dinosaurs. At some point we will need to get aftermarket kits and swap out the compressor and mounts. Just one more part to be obsolete soon. There data base checks all across the country and there was 210 left.

[meandmit]

I tried the clutch test...dead, doesn't do a thing, notta. I can't believe no one offers a clutch, I'd hate to have to buy a compressor just for the clutch...guess I'll keep looking

[pennyman1]

go to the starquest forums and ask for someone who removed the a/c to get the compressor with clutch - if you are lucky find the small sanden compressor with mount - same as all the new cars - I lucked out and found the bracket after looking for 15 years and bought 2 of the old large sanden compressor brackets on ebay before that