problem with cooling fans not coming on


Asked by Jul 18, 2007 at 12:13 PM about the 2003 Chevrolet Impala Base

Question type: Maintenance & Repair

cooling fans don't come on,when driving,replaced fans,replaced water pump.and temp sensor 3 times,still not working... but if I remove 1 wire from temp sensor fans come on but temp gauge show zero..Now air conitioning won't work check all fuses and relays all good! but can remove relay from air condition compressor and jump it and air works! what show I check  or do now...

22 Answers


Sounds like the relay for the cooling fans is bad. This is a common problem. Removing the wire from the temp sensor puts the fans into stay-alive mode, and they run constantly as you found out. Have the relay replaced and you should be fine. As far as the AC, it is most likely related to your cooling fan problem. In order not to increase engine heat, the AC is determining that it has to stay off to keep the engine cool. Solve Job 1 and you should have Job 2 in the bag.

37 of 37 people found this helpful.

bull ...these cars have problem with bcm ,,,and ecm's with one car the ac compresser comes with ac off ...and over heats cooling fans will not come on !!!!!

28 of 28 people found this helpful.

Aflores1955, what did you finally do to fix this issue? Was it the cooling fan relay? I have the exact same issue on my Silverado, and everything you described to try, I tried and it behaves just like your car does. If you can let me know.

20 of 20 people found this helpful.

I too am having same issue. I have replaced all three relays, ECT, fan assy (due to one fan burnt out), had BCM and PCM checked (both good), all wiring checks good, all signals at correct places but still no fan activity except for 10 seconds every couple of minutes.

29 of 29 people found this helpful.

I replied to "Fan Problems" on this page you can read what I did for my 2000 imp, I replaced nothing but just cleaned contact points on fuses and relays(note that they all checked out good beforehand). My fans hadn't worked at all for two years, then voila! Might work for you.

22 of 22 people found this helpful.

02 impala, fan fuse kept burning out. ac fan still working but cooling fan fuse kept burning up as soon the fan start up.

34 of 34 people found this helpful.

#1 fan fuse blows when I turn the ac on in 2001 Monte Carlo SS

15 of 15 people found this helpful.

Try removing all fan relay's coat them with dielectric grease, plug them back in and this should work.

7 of 7 people found this helpful.

From were you replace cooling temperature sensor??if its autozone or o reilly u are having a big headache if my opinion is good 100% it would work if you buy it from the dealer cost around 40 dollars but it works

4 of 4 people found this helpful.

I have a 2000 malibu Ok im having almost the same problem my ac comes on when I start the car blows hot air.. for 3 min n but my fans still dont come on and slowly my ac cuts off...I dont have relay 10 or 6 would that stop it from wrking

6 of 6 people found this helpful.

Your a/c could possibly have a leak...check for freon leaks...maybe with soap bubbles ??? :)

1 of 1 people found this helpful.

09 impala fan came on high and stays on the whole time I'm driving but A/c don't work ... where is the relay switch so I can clean and electric grease and see if that works first

18 of 18 people found this helpful.

Make sure the PCM is well grounded. Fan and relay circuits route thru PCM to ground in order to operate. If not well grounded, fans won't operate. Check PCM ground wire- usually black/white wire- to make sure it is grounded to negative side of battery.

5 of 5 people found this helpful.

i agree with Kenair , check computer grounds

1 of 1 people found this helpful.

Had this same issue with my 04 impala and I tried all suggestions listed here with no luck. The fix was to purchase a used ECM from ebay and take to dealer and get it programed to you car. Fan Work now and also AC works.

2 of 2 people found this helpful.

kereynol, what did you do to end up fixing this issue? I haven't been able to fix my 2006 imp yet either with this issue.

2 of 2 people found this helpful.

I have a 2001 monte carlo, the fans don't come on until is almost in the red zone on the temp Guage, I've replaced the rad, water pump, thermostat, and both rad lines. Still over heats because the fans Dont turn on. How do u fix this?

8 of 8 people found this helpful.

First thing I'd look for is DTC's. Then check fan motors. You can "hotwire" them. If the motors work check the relays. If all that checks out, look up cooling fan relay control circuits on the web. Seems this basic problem has been happening for a few years. Also on GM's there are at least 5 inputs and 6 conditions that control operation of the cooling fans.

1 of 1 people found this helpful.

Almost forgot to tell you to bleed all the air from the cooling system.


I have 01 and my fans aren't commimg on and ac is not getting as cold as it should I have cleaned both boxes and different sensors and still nothing but I can take a piece of wire and put it from ground on battery to one connector on 2nd biggest relay on bottom and only one fan comes on so any help plz

1 of 1 people found this helpful.

If memory serves correctly; there are 5 or 6 different control inputs to the body control computer. The body computer switches the relay ground circuits on or off depending upon the various input values. If the relays are all functioning correctly, then you'll want to check the engine coolant temp sensor, the wiring from the relays to pcm, and the a/c charge level. For an '01 the freon charge should be about 2.2 lbs. Off the top I'd say that your problem sounds a lot like the a/c system needs a recharge.


Almost forgot to mention that the a/c low pressure side sensor also provides an input to the body pcm. Also if memory serves on this; low side pressure needs to be at least 40 PSI in order for the pressure switch to send the signal to pcm.

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