Cooling Fan

halladp · **Joined:** Tue Oct 28, 2014 2:50 pm **Posts:** 2

Dear All new to the forum, but it has already been a great help. I have a Jeep liberty 2006 limited CRD Diesel. Has any one encountered an issue with the cooling fans not running. I had a mechanic who pulled out a relay or fuse looking thing. It is square with some plugs and the fan works but if this fuse is in the fan will not work. He say he has seen this before. There does not seem to be anything else affected with this fuse/relay pulled out but I do not like the idea of a part that is supposed to be there not in. Does any one know if this has been an issue and what the fix might be?

Hexus · **Posted:** Tue Oct 28, 2014 3:07 pm

Post a picture of what relay he's talking about and we'll all chime in on why it's a bad idea to unplug it.

papaindigo · **Posted:** Tue Oct 28, 2014 3:53 pm

I assume you mean the electric fan just behind the grill. If so it has 3 "speeds" 1) off, 2) on low speed, and 3) on high speed controlled by some interaction, don't ask me, between coolant temp and AC operation. Take a look at the power distribution center listing (diesel) in your owner's manual, download a copy of Sir Sam's NOOB guide or the owner's tab on Jeep.com if you don't have one (it's hidden on a shelf in top of the glove box). Did he pull relay R34 or R40?.

flash7210 · **Posted:** Tue Oct 28, 2014 3:55 pm

There are two fan relays labled fan high and fan low.

If you pull any one of those two, the fan will turn on at low speed.

So, why do you think that your electric fan is not working?

Under normal conditions the electric fan will only turn on when the air conditioning is on.
If the A/C is off, it wont turn on till the engine temp gets to 205 deg F.

Does the fan turn on with the A/C on?
It may not turn on right away. Might take a minute or two depending on how hot it is.

halladp · **Joined:** Tue Oct 28, 2014 2:50 pm **Posts:** 2

Thank you all for your responses. They were a great help. Here is my next question. As with the relay out the fan does run presumably on low. Therefore it would seem to me that the fan does not need to be replaced so if the fan does not activate with the a/c on and the temp. of the engine above 205 degrees is there a thermostat or other problem I should check to find out why the fan is not coming on?

flash7210 · **Posted:** Wed Oct 29, 2014 4:08 pm

First: make sure both fan relays are working.

Does the A/C work at all? Does the compressor kick on and does is blow cold air?

There is a pressure swich on the A/C line (cant remember if its the high or the low pressure switch) that will activate the fan. If there is no pressure, the A/C will not work properly and the fan will not come on.

There is also a engine temperature sensor on the thermostat housing. Actually I think there is more than one, but somehow the computer takes a reading from a sensor and when coolant temp reaches 205 F it will turn the fan on.

I dont know what the weather is like where you live but its starting to get cooler, even here in N Florida. Its quite possible that your engine temperature is not reaching 205 F and may not hit that point until summer. If you have the factory thermostat on the engine, your engine temps are probably staying around 185 F or so. If your thermostat is bad, engine temp may be less than that.

So, whats really going on with your CRD?
Is it overheating?

papaindigo · **Posted:** Wed Oct 29, 2014 4:22 pm

I'll speculate a bit:
1. pull one relay - does the fan run? Reinsert that relay and pull the other one - does the fan run? If so I would speculate that the circuit recognizes the pulling of the relay(s) so both power to the fan and the fan are ok.
2. I don't know how to test relay function. Normally I'd say swap in a similar relay and see what happens but both the Hi and Lo relays are Full ISO Relays. If I was swapping in relays I think??? it would be best to swap in other relays in both slots and I'm not sure you have 2 to swap in. I know the heater blower relay can be used but I don't know if the ASD relay can be pulled and used. PS. I wonder if you could pull each of the Hi/Lo relays and put them in the heater blower relay slot on the theory that if the heater blower does not work for 1 or both of the Hi/Lo relays swapped in then you have ID'd bad relay(s). Someone who is better on vehicle electrics needs to weigh in on this.
3. Assuming 1 and 2 don't help then I'd speculate that you have issues with the sensor(s) that trigger the fan. This should not be a CRD specific issue so any decent AC shop should be able to help. I cannot as I don't know what sensor(s) are involved.

I did just start my CRD and flip on the AC in recirculate mode and can say the electric fan, which I know works, did not come on at least not it the 30 seconds or so I let the vehicle run.

Cooling Fan

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