Weird?

dntlkbak · **Posted:** Sun Jan 17, 2016 12:21 am

So driving home this morning it was cold (-35 C), yes that is cold. I have never seen the electric fan run on my Liberty since I bought it new in 2006, But when I pulled into the garage this morning it was running? the engine temp was normal to a little colder than usual due to the extreme cold. Any ideas, I just replaced the coolant with new proper stuff from FCA and the proper mix when I replaced the engine a couple months ago. Everything was working ok, just weird why the fan would be running as it sure wasn't overheating.

joe_ · **Posted:** Sun Jan 17, 2016 1:12 am

If you had the HVAC mode knob turned to the defrost position, I think the air conditioning is also engaged to dry the air coming out of the vents. And according to the service manual, the electric fan may come on if the A/C is on. Do you remember if you were you using the defroster?

WWDiesel · **Posted:** Sun Jan 17, 2016 12:17 pm

If your HVAC switch was in either of the defrost positions, the AC compressor will be ON and the electric cooling fan will be running.
The switch can be modified to prevent this if you so desire as some including myself on this list have done.
This is one way to make the mod:
http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?f=98&t=83570&p=883743#p883743

Some have simply opened up the switch and covered the affected metal tabs with some black electric tape to keep the circuit from completing when the switch is in one of the defrost positions.
http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?f=98&t=83570&p=883740#p883740

Either mod will prevent the fan and AC compressor from running when the HVAC switch is in either of the defrost positions. The operator will then have total control by depressing the AC button when AC is wanted with defrost.... :wink:

geordi · **Posted:** Sun Jan 17, 2016 7:36 pm

Still - it doesn't make any sense that the 2hp or so of the AC compressor could be creating enough load on the cooling system to overheat the engine?

This is what I don't understand right now. It makes no sense.

flash7210 · **Posted:** Sun Jan 17, 2016 7:55 pm

Its not overheating.
The electric fan comes on because the AC pressure switch tells it to.

papaindigo · **Posted:** Sun Jan 17, 2016 8:57 pm

Check the Owner's Manual - the AC compressor runs in a variety of vent modes, to dry out the system air, regardless of the position of the AC switch. If the system is in one of those vent modes that triggers the AC compressor then the electric fan will run if the system "tells" it to run. AFAIK that fan will run if a) coolant temp is over a certain degree, no clue what; or b) if the AC system switches tell it to run. I'm not an AC person but my bet is the AC "freon" is low which makes the AC system switches unhappy hence the fan runs. Get AC system checked would be the first step. Alternatively one of the appropriate switches could be bad.

apardo001 · **Posted:** Mon Jan 18, 2016 9:25 am

Agree with papaindigo, low pressure reading causes the electric fan to turn ON, even if you're not using the A/C in any position... get the A/C checked. Or just accept the Jeep has a mind of his own :mrgreen:

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