Driver side radiator fan is not working and car is overheating

JOSHPB

MEMBER
1999 CADILLAC DEVILLE
4.6L
V8
AUTOMATIC
102,000 MILES

My car is overheating, much seen thread. I noticed that the driver side radiator fan is not on. I am looking for any indication other than a blown head gasket as to why it is not on. The reservoir tank is full just flushed, new upper radiator hose. I have seen threads on purge lines could that be connected to my problem? I am trying to figure all this out without going into a shop due to financial issues at the moment. Please help. Much appreciated.

Thursday, October 20th, 2016 AT 12:57 PM

3 Replies

HMAC300

MECHANIC
48,601 POSTS

Check fuses and relay for fans in under hood fuse box. then check for a bad connection or bad fan. Here is a guide to help check for power and the fan wiring diagrams so you can see how the system works.

https://www.2carpros.com/articles/how-to-use-a-test-light-circuit-tester

Check out the diagrams (Below). Please let us know what you find. We are interested to see what it is.

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Thursday, October 20th, 2016 AT 3:47 PM

JOSHPB

MEMBER
2 POSTS

Thank you I will for surely take a look at them. Just for reassurance purposes would a water pump, thermostat, purge line be a cause for the fan not to be moving? I have a lot of people in my ear saying this and that, which is fine I like to be able to look into anything helpful. I saw on a video a man cleaned a metal tube that was connected to the reservoir tank. It was completely clogged. Any connection to the fan? And one more question for now, are both fans supposed to be on when I start the car? I have heard both, yes they are, and no they turn on at different temperatures.

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Friday, October 21st, 2016 AT 10:47 AM

AL514

MECHANIC
5,330 POSTS

If your car is over heating both fans should be running, both fans should also be running if you turn the A/C on. Try the A/C if only one fan is still running there is either a problem with one of the three fan relays or the fan motor itself has gone bad.

There is a 50 amp maxi fuse (#7 in 2nd diagram) which powers both fans on two different circuits. This fuse is located in the engine compartment and neither fan would run if this fuse was blown. You can easily check each fan for power with a test light. Right fan has power on light blue wire and Left fan has power on black wire.

The ECM commands when each fan comes on. It does not command both fan unless A/C is on or excessive temps are reached. If both fans were always on the car would cool too fast and harder for the ECM to keep it within operating temperatures.

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