Nitrojunkie1029

Im working on a cherokee and the electric fan does not come on when the AC is on. I can jump the relay and then it works. I bought a new relay and that did not work either. I can still jump it and it works. Help would be appreciated. Thanks

mikesignal

on my 2000 the e-fan only comes on when temps reach 218

xjfirefighter

I just spliced into the wiring and ran it to a switch on mine. I also tied it into my ext. Idle so in park the rpms are up and the e fan is on.

ThatAintStock00

My 2000 only comes on when the temps reach above 210* - Jeep changed the "on when AC" set up at some point. i can't recall when.

SilverHaze

It is the coolant temp switch in the t stat housing. My jeep was getting really hot because the e fan was not coming on ever.

94XjSport94

In 00-01 models the AC has to reach a specific pressure.

CCKen

How hot is "Really Hot"?

You shouldn't need to rely on the radiator fan to manage your cooling system. Address the issues that cause really hot coolant temps then address the radiator fan.

Just say'n bud.

SilverHaze

I addressed the issue that was causing the hot coolant and it was the coolant temp switch. If the fan wasn't needed then Jeep would have never put it on in the first place.

Really hot = Hotter than 215

CCKen

What coolant temp switch?

I'll have to double check, but I think the fan won't come on under overtemp conditions unless the coolant temp reaches 223*F for the 2000 and 2001 XJ's.

ThatAintStock00

AC pressure has nothing to do with the electric fan cycling. I can run the AC and as long as my coolant stays below 218* (temp cut on for the fan) the efan will never cut on.

I'm almost 100% positive that the efan is programmed to cut on at 218* and back off at 195* to keep your engine cool. Mine rarely cuts on; I thought it was broken but my cooling system keeps everything in check and it's not needed.
If your cooling system is functioning properly the efan will rarely come on.

Things to check:
1) wiring - look for any kinks, cuts, corrosion
2) burp the system - you could have a really stubborn air pocket
3) Sensors/relays - replace temperature sender and fan relays

CCKen

There seems to be some confusion concerning the coolant temperature setting at which the electric cooling fan operates on the 2000 and 2001 XJ with a 4.0 Liter engine.

For the 1999, and earlier XJ's, approximately 218° F is the coolant temperature at which the electric cooling fan turns on and 209° F at which it turns off.

Here's data from the 2000 XJ FSM, Section 7 (2001 is the same):

Electric cooling fan 4.0L: With or without A/C request the electric fan will come on only when the coolant temperature is at least 223° F, and will remain on until the coolant temperature drops to 217° F or below. Regardless of coolant temperature, when air conditioning system pressures reach 300 +/- 20 psi the electric fan will engage and continue to run until the A/C system pressure drops to 235 psi minimum, then the electric fan will shut off.

Additionally, there may be confusion about the function of the electric cooling fan operation when AC is requested on the 2000 and 2001 XJ. The 2000 and 2001 XJ has a Dual Function Pressure Switch that functions much differently than earlier XJ's. Here's data from the 2000 XJ FSM, Section 24, (2001 is the same) :

DUAL FUNCTION HIGH PRESSURE SWITCH
(4.0 L)

DESCRIPTION
The Dual Function High Pressure Switch controls both A/C clutch engagement/disengagement, and electric cooling fan operations. The switch is located on the discharge line near the compressor. The switch is screwed onto a fitting that contains a Schrader-type valve, which allows the switch to be serviced without discharging the refrigerant system. The discharge line fitting is equipped with an O-ring to seal the switch connection.

OPERATION
The dual function switch is connected in series electrically with the low pressure cycling clutch switch between ground and the Powertrain Control Module (PCM). The switch contacts open and close causing the PCM to turn the compressor clutch on and off. This prevents compressor operation when the discharge line pressure approaches high levels, and also reduces electrical surging from compressor clutch engagement.

The dual function switch controls the electric cooling fan operation by monitoring refrigerant line pressures. When the discharge line pressure rises above 280 to 320 psi the fan will turn on. The cooling fan will turn off when the discharge line pressure drops to 235 psi.

The dual function switch controls the A/C clutch operation by disengaging the clutch when the discharge line pressure rises above 450 to 490 psi. The switch contacts will close and allow A/C clutch engagement when the discharge line pressure drops to 270 to 330 psi.

94XjSport94

That is what I was getting at. I just didn't have a FSM lol

ThatAintStock00

That is some interesting information. Good to know for the future.
Perhaps my switch has been bad for the last 5 years or my cooling system is that good.
Awesome gentlemen, thank you.