Fan will not come on and overheating
11-15-2003 | 04:26 PM
#1
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Joined: Nov 2003
Posts: 2
Fan will not come on and overheating
91 Camaro rs with a 305. The engine keeps over heating and the cooling fan will not come on. I turns on with the a/c being on but won't otherwise. Changed out the fan switch on the head and the temp sensor on the front. Am I looking at a thermostat problem?? Or a bad water pump maybe?? Still doesn't make sense why the fan will not turn on. Any ideas!!??? There is good coolant in it and the rad is good as well. No leaks anywhere.
11-15-2003 | 04:41 PM
#3
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Joined: Dec 1969
Posts: 1,150
From: Phila., PA
Test the fuction of the temp sensor by taking the single wire off it and grounding it. That will activate the fan relay and the fan should come on. If not, then the problem is in the wiring somewhere. On a single fan system the ECM only controls the fan when the A/C is on. Under normal conditions the switch in the pass. side head is the only thing that turns it on based on engine temp.
The temp switch in the head can vary. On a single fan system the switch turns on around 215-220* and is the ONLY thing that signals the fans to come on (besides turning on the A/C). On a dual-fan system the ECM controls the fans and that temp switch is the "switch of last resort" if all else fails it turn them on around 235-240. SO....... it's important you have the correct temp switch for your application.
The temp switch in the head can vary. On a single fan system the switch turns on around 215-220* and is the ONLY thing that signals the fans to come on (besides turning on the A/C). On a dual-fan system the ECM controls the fans and that temp switch is the "switch of last resort" if all else fails it turn them on around 235-240. SO....... it's important you have the correct temp switch for your application.
11-15-2003 | 04:45 PM
#4
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Joined: Nov 2003
Posts: 2
If the relay was bad then the fan would not work at all correct?? But it does come on with the a/c but I notice the a/c is cycling on and off every few seconds. I will try ground out the wire and see if that helps or not, but this one has got me stumped. The guy at napa said there was two different switches and the one we got had the correct threads and connector on the end but the end that goes in the head was bigger than the old one. The new one is very fat and the old one was alot more skinny looking (sorry for the technical jargon!
) It idles fine for a few minutes then goes right into the red and no fan.
) It idles fine for a few minutes then goes right into the red and no fan.
11-15-2003 | 05:50 PM
#5
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Joined: Mar 2002
Posts: 2,446
From: Yelm, Wa USA
if the whole system seems to work (good relays what have you) Try hard wiring your fans to your battery then turn on the key if they both come on then its a wire problem from the relay to the fan. If they dont come on then its most likely the fan themselves or a wire problem someone in the system.
I had the same problem all my relays were good, new thremostat, everything but the car still over heats. We just ended up hard wireing the fans the the battery
I had the same problem all my relays were good, new thremostat, everything but the car still over heats. We just ended up hard wireing the fans the the battery
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