Hi
My Aux pusher fan is not turning on when the jeep heats up or when I turn on the AC/defrost. The fan motor works, I have pulled both the hi and low relays in the fuse box in front of the battery. Pulling one relay turns the fan on, plugging it back in shuts it off with or with out the AC being on. Do I have a bad relay? or is there a fan controller or another switch that makes the fan turn on with the AC or defrost.
Thanks
2005 CRD with tow package.

Pulling one fan relay, either one, makes the fan turn on LOW.
Pull both relays and the fan will not turn on at all.

Two things make the electric fan turn on HIGH.
1. Engine coolant temp gets above 205 deg F
2. Air conditioning being turned on
If its not coming on with the AC, check the freon level and check the LOW and HIGH pressure switches.
Also, if its still cold where you are, it might take a little longer for the fan to turn on.
Turning the AC on does not make the fan turn on immediately. Sometimes it takes a few minutes.

_________________
U.S. Army Retired

Thanks for the reply
The AC has freon, and it does blow cold while driving on the road. when you come to a stop and idle for a few minutes the AC becomes less cold, the electric pusher fan does not kick on. Iam not sure how to check the hi and lo switch on the AC. The pusher does not kick on even after a long hill climb on the highway. My fan clutch on the belt driven side is new and pulls a good volume of air. I just want to check for correct operation of the pusher fan as I will be trailering for a 1500 mile trip in the near future and do not want any problems on the road.

You've already confirmed that the fan works.
But the computer isn't recieving the necessary input to activate the fan.
That, or the relays are bad.
I suspect the AC low pressure switch.
It's down between AC compressor and battery.
Unplug it and firmly plug it back in.
If that doesn't fix it try the relays.

_________________
U.S. Army Retired

Could you please help me with my fan issue? I had my jeep into two dealerships over a year ago to fix some grounded wires and a fried computer. It wasn't until later that I found out one of them cut the cord that leads to the fan. I can see the wire coming out of the fan motor and the plug from the wiring harness is still attached to the fan plug, but I can't find the other end of the line. Can you let me know where the original wires from the harness come out? I suppose it would be easier to just rerun my own wires, but I'm not even sure which sensors I should be connecting to to have it turn on.

I don't even know why they cut it, but I would like to trace it back to the appropriate source and make it work again. Last summer I hat the temp gauge go up for a hot second, and I thought that I was blowing the head gasket. I would like to get that fan working again.

_________________
2005 Black KJ Sport CRD,
GDE Full Torque ECO TUNE, GDE Transmission ECO Tune,
Samco British Racing Green Hoses
Build Date 1/05
200k miles.
Original Owner

I'm sorry, I just hijacked your thread. That was rude. I typed before I thought.

I was thinking that if this thread is discussing the problems of the fan, then I might be able to figure out how the whole system works from beginning to end.

I'm guessing I just had a grounded wire, and the jerk cut the whole thing out.

I was having problems with the AC compressor turning off and on and creating a serious drag on the engine while at idle. One shop filled up the freon, "fixed" a grounded wire and the problem went away. I'm now thinking he's the one who cut the whole front fan out if they are part of the same line. Could a bad relay have been causing the problem all along?

_________________
2005 Black KJ Sport CRD,
GDE Full Torque ECO TUNE, GDE Transmission ECO Tune,
Samco British Racing Green Hoses
Build Date 1/05
200k miles.
Original Owner

I checked the relays, moved them around in the fuse block and unplugged and and then reconnected the AC switch down by the compressor. I will have to go to my mechanic and have him double check the freon level as I only have one of the cheap fill gauge from Walmart. On the gauge dial the indicator fluctuates between 25 and 38 at 60 degrees Are there any other sensors that control the electric fan? any in the radiator, I looked and could not find one.

Those pressures were taken on the low side of the AC system, correct?
If so, that's pretty normal.
Is 60 deg F your normal outside temperature right now?
If so, your AC system isn't working very hard and therefore may not cause the electric fan to turn on.

Wait till summertime. If the fan still seems to not be working have your AC system checked.

_________________
U.S. Army Retired

I hooked the gauge up to the port by the washer fluid fill cap. The local high temps have been reaching around 60 degrees daily.
This problem has been on going since last summer, when temps would hit 90 degrees. The new Hayden hd clutch fan took care of the cooling issues I had, but the electric fan would not come on since last summer before the Hayden hd clutch. I had came close to over heating a couple of times while pulling a trailer on a grade last summer, both times the E fan did not come on. Thats why I ask if there are other sensors which feed to the computer telling the fan to come on. I checked the obd2 code and it comes up with an egr and FCV issue because I have the Weeks elbow installed. Other than that no other codes.

I only know of two things make the electric fan turn on.
1. Engine coolant temp gets above 205 deg F
2. Air conditioning being turned on, AC pressure switch

You have already changed your fan clutch. So that should prevent engine temp from getting above 205. (unless you have a way of accurately measuring coolant temp. I use the torquePro app on my android tablet to get accurate engine temp)
You have already confirmed that the fan works and the fan relays work.
That leave two things:
1. a problem with the AC system.
2. a problem with the ECU or wiring from ECU to fan relays. (i.e. the fan activation signal from the ECU isnt getting to the relays)

_________________
U.S. Army Retired

Problem solved.
Had my mechanic erase all fault codes from the ecu. I had an injector code that the mechanic thought may have been the cause.
If any one else has a problem with their electric fan, check for codes as well.
Thanks