Cooling Fan not working properly

Tiny
BENDER69
  • MEMBER
  • 1993 FORD ESCORT
  • 124,000 MILES
I have just bought this car and the cooling fan isn't cutting in to cool the engine (when I think it should). It works on both speeds when straight power is supplied to it. The temp gauge sits at half when driving. At idle or after sitting traffic for some time it wont kick in until the temp is nearly in the red zone and cuts out at the L of normal on temp gauge. It has a d2 stamped temp sensor in it. Another forum showed a Ford TSB which said A3 temp sensor n cluster gauge didnt read correctly.
when the A/C is turned on the fan works and stays on (when the A/C is turned off) until temp goes to half on the gauge.
i have bought a manual for this model car and it says to test wires at the PCM but it doesn't seem I can do that without unplugging the unit.
any ideas on what to look for next?
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Thursday, September 8th, 2011 AT 11:06 PM

9 Replies

Tiny
PROMECHANIC
  • EXPERT
The most likely cause of your problem is a faulty cooling fan relay. You can test it by switching it with another relay of the same size. It could also be a problem with your temp sensor or PCM
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Thursday, September 8th, 2011 AT 11:13 PM
Tiny
BENDER69
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Ok thanks. The low & high speed relays have different pin layouts and dont have your standard 4 pin relays number on them. So I am unable to swap them around. Photo is the low speed relay. Any idea how to test it?
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Friday, September 9th, 2011 AT 12:09 AM
Tiny
PROMECHANIC
  • EXPERT
I'm assuming this one is from the engine compartment fuse box. If so you should have a black/white wire that should have power when the ignition switch is in the "start" or "run" position. You should have a black/red wire that is hot at all times. The black/dark green wire comes from the computer and tell the fan to come on. The yellow wire goes to the fans.
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Friday, September 9th, 2011 AT 2:53 AM
Tiny
BENDER69
  • MEMBER
The photo is of the relay that sits behind/below the airbox mounted on the inner guard. It sits next to the high speed fan relay.
Looking at the photo
com is green wire which connects to high speed relay (top middle in photo)
coil is black white wire (top right in photo)
NG is big yellow wire which goes to fan
coil (bottom right) is small yellow wire.
I dont have all the same color wires u mentioned tho.
Relay in engine compartment fuse box is a slightly different type. Your thoughts?
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Friday, September 9th, 2011 AT 3:57 AM
Tiny
PROMECHANIC
  • EXPERT
I'm thinking that what you have in the picture is not the fan relay. It should be located in the engine compartment fuse box.
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Friday, September 9th, 2011 AT 4:02 AM
Tiny
BENDER69
  • MEMBER
The fan relay in the engine compartment box provides power to the fans. Power is there with key off & on. The relay in photo is the low speed relay which sits next to the high speed relay on the front fender apron as I already said. I do have a wiring diagram to reference that too.
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Friday, September 9th, 2011 AT 5:27 PM
Tiny
PROMECHANIC
  • EXPERT
Can you post it? Your diagram is different that mine.
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Friday, September 9th, 2011 AT 5:37 PM
Tiny
BENDER69
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Hope this ok otherwise I can email the file through. Barefoot_30@hotmail. Com is me
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Friday, September 9th, 2011 AT 6:16 PM
Tiny
PROMECHANIC
  • EXPERT
OK so the black/white should have power with the key in run or start.
The yellow/white wire should have power from the computer telling it to come on.
The light green should have power coming from the high speed relay.
The yellow wire is the output to the fan.
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Friday, September 9th, 2011 AT 6:27 PM

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