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XJ 99 A/C and Electric Fan

JorgeA

NAXJA Forum User
Location
Bogota-Col
Hello.

I bought a used 99 XJ laredo, auto and I think something is worng with the A/C, eventhough the A/C works when I put the speed in 1 on the control and temperature cold the electric Fan begins to work even if the engine is still hot or normal temperature. Is it right?, or I have to check the A/C?
Thanks
 
Nope, thats right, the E-fan is supposed to come on when you turn on the AC....
 
I have a similar issue. My Daughter's 2000 XJ was bought used in July 2007. The fan on my 96 XJ comes on as soon as I turn on the AC. The 2000 would not come on until the temp on the gauge went above 210 degrees. I was told that this was normal for the newer XJs. Can anyone answer this for sure? Last night I let the vehicle run (80 degrees outside temp) for 30 minutes with the AC on inside air, windows closed and the blower on high. The temp at the vents was around 42 degrees. The engine temp showed around 215 but the fan never kicked in. We gave up and went to bed. This fan was replaced last year when a blade sheared off of the OEM unit. The fan will run when directly connected to the battery. I have been told that there is a temp switch that controls the fan and also that there is a relay that controls the fan. Can anyone give me an idea of what might be going on? Thanks!
 
Thanks for the reply. I could not get a straight answer on this question as it seems everything contradicts everything else. At what temp should the fan be coming on? I may be wrong in assuming that it comes on when the engine gets too hot in addition to the trigger by the AC pressure.
 
The fan should come on at about the 215-220 range on the newer XJ's. The computer uses a thermistor threaded into the thermostat housing, however with age that sensors resolution may become diminished resulting in the computer thinking the engine is colder than it really is.
 
Are you referring to the coolant sensor? Sorry for the dumb questions. The 2000 and my 1996 XJ are much more different than I realized. I like MINE better :)
 
rbarton said:
Are you referring to the coolant sensor? Sorry for the dumb questions. The 2000 and my 1996 XJ are much more different than I realized. I like MINE better :)

The sensor (sender) at the back of the head talks to the driver through the gauge/light reading.

The one in the t-stat talks to the computer and tells it when to turn the fan on.
 
Yeah, older XJ's the electric fan comes on when the motor gets warm or with the A/C, but I believe the newer XJ's (not sure starting in what year), the electric fan only comes on when the motor gets too hot, but not depending on if the A/C is on.

96 was the last year for the seperate sensor at the rear of the head for the gauge. 97+ use the sensor in the thermostat housing for all.
 
Thanks, Guys! Lots of good info. Especially the link to the other thread that had the FSM info describing the operation of the fan in detail. My 2000, sitting in the evening sun, outside temp of 86, with windows down and AC on recirculate - max - fan on high will only get to around 60 degrees at the center duct. My 1996 in exactly the same location and setup drops to about 52.

Both vehicles have the same charge level and pressure. The only difference is that my 96's fan kicks in immediately. In the old days, the expansion valve getting dirty or defective could make that much temp difference and more, but the expansion valve on the 2000 looks nothing like that of the older models. The system in the 2000 may simply not be as efficient as the 1996 for whatever reason. Anyone else taken the true vent temp to see what you are actually putting into the vehicle?

This is how I tested mine - except for no available shade:

1. Park car in shade when checking temperature.
2. Start engine and allow to run at a fast idle.
3. Turn air conditioner to maximum cool.
4. Insert probe, full length, in center outlet duct or right hand
outlet duct.
5. Allow approximately 5 minutes for accurate reading.
6. Readings of 45o to 60o indicate a properly charged system.
In-car ambient temperature of 75o to 85o should produce
duct temperatures of approximately 45o. Higher in-car
temperatures should increase duct temperatures to no higher
than 60o.
 
Re: XJ 99 A/C and Electric Fan (Mine is FIXED)

Verified the fan was NOT coming on once the temp reached 225. Jumped fan connector to the batter and the fan worked just fine. Figured the temp sensor was working as well based on temp of engine and what was being reported at the gauge. Checked the Cooling Fan Relay and found it to be similar to my 96XJ so I swapped it in. Fan kicked on immediately (temp was at 240 or so by this time). It lowered the temp to 210 and shut back off. Left the vehicle idling with the AC on max. Every time the temp reached about 215, the fan kicked on. I think the problem is solved. And the best part...Advance Auto Parts had the part for $7.00. In case anyone runs into this problem, their part number is 35928.

Thanks to everyone for the input and suggestions!
 
ParadiseXJ said:
The sensor (sender) at the back of the head talks to the driver through the gauge/light reading.

The one in the t-stat talks to the computer and tells it when to turn the fan on.


Sorry, But on the later models the computer run All the gauges tac and speedo.
That all-in-one unit really sucks. Lose you voltage reguator on a early model and a NEW one runs under 30 bucks. Blow it in the ECU and a USED ECU is at least 100 bucks plus shipping.
Other then a tire it's the only thing I carry a spare for. If just control everything.
 
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