cooling fan not working

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  #1  
Old 07-24-06, 09:12 PM
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cooling fan not working

I have a 2002 Jeep Grand Cherokee and the cooling fan does not come on. I unpluged it and jumped it from the battery and it runs. I checked all the fuses and they are good. We ran a computer check and it said fan relay short. Cannot fine a short.
Could it be the temp sensor.
 
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  #2  
Old 07-25-06, 02:38 AM
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When it said "fan relay shorted", it's doesn't means that you have a short in wires, it's means your relay(solid state) is bad and internally shorted out, most of the time , the relay is the problem.

There's also another problem , " where's the relay located?".

It's behind the Pass/side head lamp assy, but you have to remove the front bumper cover first then you'll be able to remove the head lamp, once you get those two items out of the way, then you'll see it, not a pretty place to put it but ...... it's there.
 
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Old 07-25-06, 07:00 AM
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If its not the relay post back then we will talk. Relay coils usually fail open not short. But it is possible they will fail short
 
  #4  
Old 07-25-06, 01:17 PM
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fan trouble

Before you go to the task of getting to the relay, why not bridge across the thermostat terminals. If the fan works then, try a new thermostat. If a relay coil "shorts" of course it can not switch power (in this case its contacts would be hanging open) and if you take it out, you can simply test it on the bench. You may also be able to temporarily try another identical relay used in another circuit to compare.
 
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Old 07-25-06, 03:05 PM
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Originally Posted by volts
Before you go to the task of getting to the relay, why not bridge across the thermostat terminals. If the fan works then, try a new thermostat. If a relay coil "shorts" of course it can not switch power (in this case its contacts would be hanging open) and if you take it out, you can simply test it on the bench. You may also be able to temporarily try another identical relay used in another circuit to compare.

This's a solid state relay, there's no movement part inside the relay, no coil, no contact point, only circuit board packed with jelly/silicone inside (hence solid state), and there's only one for coolant fan circuit, there's no other relay in this jeep can be subtitute for.
 
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Old 07-25-06, 04:19 PM
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Yeah, you know, one of those pain in the butt relays that costs a fortune and does nothing more than your typical $7 relay that's good enough on a thousand other makes and models. Sometimes I truely believe car companies sit around and think of ways to make life more difficult for end-users.
 
  #7  
Old 07-26-06, 04:12 AM
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simple checks

Solid state or whatever. This trouble can be quickly found by simple continuity checks and bridging. It's a simple series circuit with two simple elements other than wiring to be looked at.
 
  #8  
Old 07-26-06, 05:50 AM
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suspect new guy pretty much told you what is probably wrong you may want to see a shop for repair and testing to find out for sure.
you do not want to jumper anything as your vehicle doesnt have a temperature switch instead it uses sensors to determine when the computer turns on and off the fan.
 
  #9  
Old 07-26-06, 06:36 AM
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I don't see what the big deal is with solid state relays. They operate differently than traditional relays and a traditional continuity test may not work.

Give me schematics I give test procedure and answers.
 
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