• NAXJA is having its 18th annual March Membership Drive!!!
    Everyone who joins or renews during March will be entered into a drawing!
    More Information - Join/Renew
  • Welcome to the new NAXJA Forum! If your password does not work, please use "Forgot your password?" link on the log-in page. Please feel free to reach out to [email protected] if we can provide any assistance.

Electric Fan not running when ac is on!!

cdw25271

NAXJA Forum User
Location
Ripley, WV 25271
I have a 2000 cherokee that the electric fan quit running when the ac is on. It still comes on if the temp gets up to 215 deg. Any ideas from anyone with a wiring diagram. Does the fan go through the ac relay also?:twak:
 
i have a 2000 too and its electric fan does NOT come on with the AC either, only when it gets to 215+ which is rare. I think i read somewhere when i searched it a while back that different years are wired differently. I though my XJ was broke for 3 days b/c the aux fan would not come on. Luckily i had it running a long time while i was searching for this bug and it came on on its own. BTW, what temp does yours run at according to the gauge. I have an OEM setup, minus at 195 degree Standt SuperStat running 50/50 coolant. mine hovers around 210, no more than the needles width off that 210 in either direction ... whether idling or on interstate. I am wanting to get it to run under the 210 mark on account of our bad heads (0331).
 
I think the fan comes on two ways, A/C compressor even in defrost mode and the ECU/engine temp, I think they use two different relays too but I'm not positive so one relay, the A/C could be bad..
 
thebrick said:
A good read related to this issue...the fan on my 2000 XJ (electric fan) doesn't come on either when AC is first turned on. It has the mechanical fan to keep it cool most of the time...

http://www.findarticles.com/p/articles/mi_m3102/is_10_123/ai_n6358902

Intersting article. Also from the FSM:

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 1900 to 2200 kPa (280 to 320 psi) the fan will turn on. The cooling fan will turn off when the discharge line pressure drops to 1600 kPa (235 psi). The dual function switch controls the A/C clutch operation by disengaging the clutch when the discharge line pressure rises above 3100 to 3375 kPa (450 to 490 psi). The switch contacts will close and allow A/C clutch engagement when the discharge line pressure drops to 1860 to 2275 kPa (270 to 330 psi). The Dual Function High Pressure Switch is a factory-calibrated unit. The switch cannot be adjusted or repaired and, if faulty or damaged, it must be replaced.
 
so have you fixed your fan? if so, how. and did you have the intermittant warm AC like the article described?
 
I'm trying to get a set of gauges. I have one that does the low side while filling but not the high. I tried adding just a little freon yesterday and it seem to help a little. When it gets hot enough for the electric fan to kick on due to heat the low side dropped to about 32 psi. My new question would be should the electric fan be running when adding freon so the pressure is pulled down. If so I think it is still a little low and if I add more maybe the fan will kick on if high side gets high enough. As soon as I can get gauges to see what the high side pressure is I will post what I find out.
 
my AC gets week intermittantly and eventually blows ambient air temp... then it will randomly kick back on... can take over 1/2 and hour before the air gets cold again. my car is doing exactly what the car in the above article link did. so i guess i have to take to to an AC shop to have the AC clutch checked out.
 
langer1 said:
So with a 2000 and up the e-fan only comes on when needed so IF the AC is working ok then so is the fan.
I was going to say the same thing. Sometimes the fan will run when the A/C cycles. Sometimes it will not. I think it has a lot to do with the ambent temp. IIRC the line psi isn't high enough to actavate it unless the ambent temp is pushing 100*.
 
My buddy told me about this. The fan will only turn on when the A/C has a proper charge in the system, regardless of the year. I watched him recharge his 89 and the compressor and fan turned on, once there was a charge in the A/C system. Same thing with my 95. Now the fan instantly turns on with the A/C and the defroster.
 
Trailbst said:
My buddy told me about this. The fan will only turn on when the A/C has a proper charge in the system, regardless of the year. I watched him recharge his 89 and the compressor and fan turned on, once there was a charge in the A/C system. Same thing with my 95. Now the fan instantly turns on with the A/C and the defroster.
True but it also runs once the engine temp gets up over 230f
 
Back
Top