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Mike S.
Mike S., ASE Certified Technician
Category: Oldsmobile
Satisfied Customers: 7298
Experience:  25+ years experience and ASE Certified.
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94 Ciera; compressor & condensor fan does not run at all when

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94 Ciera; compressor & condensor fan does not run at all when ac is switched on. Is it the relay(?, or a low pressure switch(?) or something else?

I assume you mean blower motor fan. Does the blower motor fan come on when it's on heat?

The only thing I see in common between the 2 is they share the same fusible link A. For the wiring diagram, click here and test on each side of that fusible link with a 12 volt test light or voltmeter. It should be hot all the time.

No, actually I looked at that too fast. That fusible link doesn't power the ac clutch. Check those fuses and then onto the relays if the fuses are ok, so let me know.
Customer: replied 3 years ago.

Hello Olds 442 :)


Fuse would be the first step; then the AC relay would be the 2nd step. Neither the AC Compressor Clutch or the Condensor Cooling Fan will come on (the blower fan works fine; all speeds & settings).


Where is the AC Relay? (94 Cierra). Their are four relays on the passenger side, between the radiator and headlight, not far from the Compressor.


If the Relay is good, is it possible a low pressure limit switch is stopping the AC Compressor from coming on? Thanks!





Ok, then they do share fusible link A. Does the primary cooling fan work? Is there a lid or anything that shows what relays are what? I'll see if I can look that up.

What engine?
Customer: replied 3 years ago.

3.1 V6. 100k. Stock. Not clean; but stock :)

Here, this shows the location of all 3 relays.


Mike S. and other Oldsmobile Specialists are ready to help you
Customer: replied 3 years ago.

Under the hood? Hmm! That is interesting! I do not recall seeing this under the hood (but I know it makes sense). I was looking to buy this car for my niece; and I did not see this typical black box. So I need to follow-up; I am suprised I missed that.


Could part of this problem be a low pressure limit switch?

It's hard to say. I don't know if that would cause the cooling fan no to work. I would need to find a wiring diagram that shows how that is wired. So, this is a car you are thinking of buying? Is the seller allowing you to do these tests and replace an parts?
Customer: replied 3 years ago.

Yes. But I really was trying to get a general idea if this car is worth the money. If the AC repair can be completed for $150; no problem; I will buy. If the AC repair costs $500... I will still buy, but at a lower price. The car is quite nice... and I tried to find an on-line schematic that would help me diagnose trhew problem, but I could not find one.

I think you are right about the pressure switch. I think thier is a threshold delay on the switch. For example, it thier is no pressure in 15 seconds, the compressor disengages.


If the compressor works, and the issue is a bad relay or a fuse, and only a recharge is need, this car seems to be a good value.


Based on your experience w/ E-platform GM cars, what is your best guess on the root cause of the failure. Recall that the Seller was quite surprised that the AC system dod not cycle on (and I think he is telling the truth).


Please share your closing thoughts on this AC issue. I am very satisfied with your help! You have been great!!!


Did you at least press on the schrader valves and see if there was any pressure?

Since he was truly surprised, a bad electrical part. A fuse, fusible link or relay. If it were low on a charge or even leaked, he would have known.

Customer: replied 3 years ago.

That is a great observation! I did not press on the shrader valve! I looked right at it (the cap was missing at valve by firewall; and no dirt in valve area) but I did not press on it! I should have! What a great idea!


This has been a great discussion! Thank you very much for the great advice! The only thing that really has me puzzled is why I did not see the black box with the fuses and relays in it. Maybe it was under the dash(?)... I did not look under the dash.


By the way :) I worked at GM's Oldsmobile Division in Lansing Michigan; we built "442's" there (Cutlass) untill 1984 and also 88's and 98's years before. Back in 66 and 67 we built Toranados there. It was a great place to work; but GM's mgmt and materials were lousy (and I was in mgmt :)


Thanks again for a great discussion! Blessings to you and your family!

Scott Wheeler - Charlotte, NC

Rom 8:28 :)



Those were the days!