A/C doens't work du to fan failure

So... try my A/C on my 98 sport XJ .... not enought freon ...
Make a pressure test ...hold the pressure without leak 15 minute in a row.... fill it up, aded one pound, and realize the electric fan of my XJ doesn't start when i start AC... so the A/C rad can't be cooled and getting to hot to finaly bypass by a relief vavle and re empty my circuit...

I know the thermostatic fan in pluged near the thermostat... if i unpluge this wire ...fan SUPOSED to run non stop ... if not the fan is probably dead ..if yes maybee the sensor..


Did i miss something??? where is the relay to chek it??

common issu on XJ ??

My pregnant wife is a bit piss of about the xj without A\C ....:wierd::rattle:

Thank's you

S.

i just went through alot of this on my 88. saddly the system isnt the same otherwise i would try and give a hand.

in the mean time hand her a wrench.....

If your PDC (underhood fuse/relay block) looks like this, the fan relay is #4.

http://i266.photobucket.com/albums/ii244/AHhub/forum stuff/DSCF5572.jpg

If the coolant temp sensor in the thermostat housing is bad, the gauge on the dash shouldn't work. If the gauge works, and the fan doesn't come on with the AC, or with the coolant temp sensor unplugged, I would check the relay, then the fan motor itself.

My 98' would'nt engage the fan with the A/C on last year. After trouble shooting I determined the fan was bad. The Dorman brand fan I got from both Autozone and Advance had the old style electrical connector and wouldnt fit. The 3rd fan from Autozone had an adaptor that fit the newer style terminal. If it comes down to the fan, check your connector and make sure the fan you buy has the adaptor or correct connector.

Here is a Fan Motor repair proceedure:

Over time, carbon builds up in the motor causing several problems. Sometimes the electric fan starts running erratically, like it does not always want to start. Sometimes, when you turn them by hand, you will feel them "cog". By this I mean that it feels like it is going past notches. A DC motor should turn smoothly.

Here is how to reclaim a 97+ Fan Motor.
1. Remove the C-Clip and metal spacer securing the blade to the motor.
2. Remove the blade from the shaft. Tap the motor shaft LIGHTLY to get it off. DO NOT PRY ON THE BLADES, THEY WILL SHATTER!!!!!!
3. Remove the three screw securing the motor to the shroud.
4. There are several tabs that are bent down holding the backing plate. Gently pry these up to release the backing plate.
5. Blow out the built up carbon dust from the inside of the motor. As the motor operates, the brushes wear depositing carbon everywhere. This shorts the segments causing the "Cog" feel.
6. Gently clean between the commutator segments to remove the carbon. A very small scribe works well.
7. Reattach the backing plate by gently bending the tabs back into place.
8. Reattach motor to shroud.
9. Reattach blade.
10. Test.

This is a, usually, one time repair as the tabs holding the back plate on tend to snap off with repeated bendings as they are just thin sheet steel. It is also possible to just buy the motor by itself. Google the part number that is printed on the motor. It is a Bosch Part.

The motor is available as a discrete part. Do not buy a cheap or "discounted" fan assembley as they are just, IMO, so much junk. You really do want a Bosch motor running the fan.

So should the electric fan run all the time if the AC is ON, or only when the temps get above a certain point?

Not that my question answers your question... but it'll be a help for me.

Thanks.

Redsnake said:

So should the electric fan run all the time if the AC is ON, or only when the temps get above a certain point?

Not that my question answers your question... but it'll be a help for me.

Thanks.

Click to expand...

I thought that it only went on if needed with 97+. As in if the temp got over 220 or so and did NOT come on just because the A/C was switched on.

Pull the temp sensor, see if the fan comes on.

hubs97xj said:

If the coolant temp sensor in the thermostat housing is bad, the gauge on the dash shouldn't work. If the gauge works, and the fan doesn't come on with the AC, or with the coolant temp sensor unplugged, I would check the relay, then the fan motor itself.

Click to expand...

The sensor in the thermostat housing is for the engine computer, the sensor in the back of the cylinder head is for the gauge on the dash.

The fan will operate normally even if the gauge is not working. They're two separate sensors.

96 is the last year for the separate sensor and gauge sender; 97+ only have the CTS in the thermostat housing, as the PCM drives the gauges.

The fan should run constantly at ~220*. It should cycle with the compressor when the AC or defrost modes are selected, at least for the 97 and I believe the 98-99 model years. It's posted around here somewhere, but the 00 or 01 models apparently only run the fan when the PCM sees ~220* from the CTS.

On the 97/98 model years, the aux fan will run with the A/C compressor or when the Engine Coolant gets to 218F. Starting in 99, Jeep discontinued running the fan with the compressor.

It may have been in 2000, but the decision was made to stop running the fan with the compressor. Apparently, folks were freaking out over the fan "pulsing" when the HVAC was set to "Defrost". I guess they did not know/understand that the A/C pulses during defrost both to dehumidify the air but also to keep the A/C system operating during the Winter.

Setpoints for 97+ Aux Fan operations are ON at 218F and OFF at 212F.

hubs97xj said:

96 is the last year for the separate sensor and gauge sender; 97+ only have the CTS in the thermostat housing, as the PCM drives the gauges.

Click to expand...

I didn't know that. I just replaced the sender for the gauge on the '96 because it had the older version on there, but the 97+ connector. I guess I figured if chrysler updated the connector on the harness, it must have been the same for all the XJ's.

:thumbup:

and it was the fan !!!

There you go...