Electric fan running all the time ignition is on.

Klem531 · **Posted:** Mon Dec 14, 2015 6:56 pm

Soooo....I have a 2006 Liberty CRD :JEEPIN:

and my electric fan right behind the grill has started to run continuously whenever my ignition is on. :banghead:

I've searched the forums and I and I've found where this has been discussed but I have not found where anyone has posted what they have done to fix it. I have tried swapping relays and that did not fix it. I have briefly looked at the wiring harness that runs behind the filter head and I didn't see any obvious issues so I plan on tearing into that a little further this weekend. I also still have my ABS/ESP, brake lights on (intermittently) and the code reader says "Loss of communication to ABS controller. Any insight would be greatly appreciated. Thanks!

papaindigo · **Posted:** Mon Dec 14, 2015 8:35 pm

That fan as 2 relays high/low (R34 and 40) if one is stuck the fan will stay on; it's not clear from your post if you checked both. If that's not it someone who understands the wiring better than I will have to weigh in. IIRC fan operation is triggered by coolant temp and/or an AC pressure switch; either of which could be bad.

flash7210 · **Posted:** Mon Dec 14, 2015 9:00 pm

There are two relays. Fan Low and Fan High.
If either relay is bad the fan will stay on Low.
If both relays are bad the fan will not turn on at all.

So, pull one relay and note wheather the fan stays on Low or turns off. Then put that relay back in.
Then pull the other relay and see what happens.

Another possibility could be a bad or unplugged AC pressure switch.

Klem531 · **Posted:** Mon Dec 14, 2015 9:27 pm

Thank you for the replies, I sincerely appreciate it. The fan runs on high constantly. I pulled the high relay and it still ran on low. I swapped the relays and no change. I bought and installed a new relay and no change. (tried the new relay in both spots and no change). After reading previous posts on this problem, I'm thinking the A/C pressure switch could very well be the culprit but I sure would like to hear from guys that have had this problem and what they did to fix it... Thanks

Mountainman · **Posted:** Tue Dec 15, 2015 12:58 am

You'll also get this if the pressure is low. Does your AC blow really cold? Might just need a recharge to get the pressure up high enough. But, if it's leaking, that can be an expensive rabbit hole. hmm, maybe one of those $30 recharge kits from the parts store is worth a shot?
The pressure switch by the AC pump is really easy to swap, but I don't know how much they cost.

Klem531 · **Posted:** Tue Dec 15, 2015 1:05 am

Now that you mention it, I did notice this past summer that the A/C wasn't blowing cold anymore but since I seldom use it I let it go... How does it being low affect it to where the fan would run all the time?

Mountainman · **Posted:** Tue Dec 15, 2015 1:13 am

Klem531 wrote:

Now that you mention it, I did notice this past summer that the A/C wasn't blowing cold anymore but since I seldom use it I let it go... How does it being low affect it to where the fan would run all the time?

The pressure switch gives the ECU a 0 vs a 1 or vise versa. It doesn't have enough pressure to close the contact, or open it...

If you don't use the AC, and don't tow heavy, or drive big grades. You can probably get away with unplugging it. Just watch you temps closely. You can definitely unplug it until next summer

papaindigo · **Posted:** Tue Dec 15, 2015 7:48 am

AC compressor cycles on a variety of vent settings even if AC switch is off. Hence if one of those vent settings is selected and AC system pressure is low the pressure sensor could keep the fan on all the time.

Klem531 · **Posted:** Tue Dec 15, 2015 7:57 am

That makes perfect sense now... I'm going to pickup a recharge kit today and see what happens. If it doesn't hold I'll have to take it to my mechanic and see where the leak is. Thank you all very much for the insight. Now if I could just figure out the ABS issue I'd be a happy camper. :CAMPING:

.

Mountainman · **Posted:** Tue Dec 15, 2015 12:11 pm

Do you get the ABS light when you hit bumps?
It's probably wire that goes to the speed sensor in the rear dif (2005) or wheel sensor wire (06) is my guess.

Klem531 · **Posted:** Tue Dec 15, 2015 1:40 pm

Mountainman wrote:

Do you get the ABS light when you hit bumps?
It's probably wire that goes to the speed sensor in the rear dif (2005) or wheel sensor wire (06) is my guess.

Yes and no... Sometimes I'll be driving on smooth pavement and the lights will just pop on. This isn't the first time I've had this problem. The first 2 times it was a broken wire in the harness going to the rear wheel speed sensors. I've rung out both front and back sensors with my fluke meter and everything checks good. I even wiggled the harneses to see if I'd lose continuity and nothing. When I hooked my code reader up it says communication lost with ABS controller so I'm thinking a bad controller or a bad wire in the harness behind the filter head. Unfortunately the ABS controller is an expensive little bugger and it has to be dealer programmed from what I understand.

Mike92104 · **Posted:** Tue Dec 15, 2015 2:45 pm

Klem531 wrote:

Mountainman wrote:

Do you get the ABS light when you hit bumps?
It's probably wire that goes to the speed sensor in the rear dif (2005) or wheel sensor wire (06) is my guess.

Yes and no... Sometimes I'll be driving on smooth pavement and the lights will just pop on. This isn't the first time I've had this problem. The first 2 times it was a broken wire in the harness going to the rear wheel speed sensors. I've rung out both front and back sensors with my fluke meter and everything checks good. I even wiggled the harneses to see if I'd lose continuity and nothing. When I hooked my code reader up it says communication lost with ABS controller so I'm thinking a bad controller or a bad wire in the harness behind the filter head. Unfortunately the ABS controller is an expensive little bugger and it has to be dealer programmed from what I understand.

I remember reading about some wiring near the controller that can also go bad. I don't remember what or why, but it's worth doing some more searching on the forum.

Mike

Mountainman · **Posted:** Tue Dec 15, 2015 6:29 pm

Josh or someone might have a controller for a better price, but I'm pretty sure it has to be an 06, Unless the 06 I had was a fluke and they were just throwing spare parts at it.

They looked the same, but had different part numbers. If you post your part number I'll check mine. I'd sell it for cheap if it's the right one, and you end up needing it. It isn't all that strange for a shorting wire to damage a chip, but it's probably a wire

Electric fan running all the time ignition is on.

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