kevin fravel

I have a 1999 Cherokee Sport that has started having problems with the electric cooling fan. It has stopped coming on and allowing my temp gauge to stay at a higher point than it normally does. I jumped my fan directly to the battery to make sure that it was still functional and it is. I found the relay under the hood and manually activated it which made the fan come on. The fan will not come on with or without the A/C on and although the temp gauge is only at 210 it used to come on around 210 and drop it down to 185 and I know that it would also come on with the A/C and now will not. I have found the temp sensor on my thermostat housing. Just trying to locate the sensor that will activate the fan. Also note that when the temperature gauge is at 210 with the heat on at full hot and the blower fan on high it blows cool air in the cab. Please help any suggestions are welcome.

Still love my first Jeep ! Just frustrated.

TonyXJ

I remember having the same problem a couple years ago. If only I could remember how I fixed it...

Does the air conditioner actually work normally?

kevin fravel

Yes the A/C does function normally.

CCKen

From the '99 FSM, edited by me:

ELECTRIC COOLING FAN, 1999 XJ

Vehicles equipped with a 4.0L engine and air conditioning has an electrical cooling fan. The fan is controlled by the cooling fan relay, which is located in the power distribution center (PDC). For the location of relay within the PDC, refer to the label on PDC cover.

When coolant temperature reaches approximately 218°F, or when air conditioning is requested, the powertrain control module (PCM) provides a ground path for the fan relay. This ground is provided to the cooling fan relay through pin C2 of PCM connector C3. Battery voltage is then applied to the fan through the relay. When coolant temperature drops below approximately 209°F, the PCM opens the ground path to the relay. This will prevent the cooling fan from being energized.

The cooling fan motor is protected by a 40 amp maxi-fuse located in the PDC. The fan relay is protected by a 15 amp fuse located in the junction block (Fuse 10).

~~~~~~~~~~~

Check fuse #10 in the Junction Block. This fuse powers the fan relay control coil when the ignition switch is in the RUN postion.



If the fan runs by jumpering the fan relay pin sockets in the PDC, the fan 40 Amp fuse in the PDC should be okay.



I suggest you replace the fan relay with a new one then do the test below. But before replacing the relay examine the relay pin cavity sockets for the relay in the PDC; make sure the pin sockets aren't pushed down in the PDC, make sure they aren't enlarged from shoving a probe/jumper in them, and make sure they are not corroded.

Remove the elctrical connector from the ECT then start the engine. The fan should run. This tests the integrity of the fan circuit, including the fan relay ground driver circuit to the fan relay control coil. If the fan still won't run, there's further troubleshooting requied.

~~~~~~~~~

Blend-Air Door

Here's a schematic of your Blend-Air Door circuit (below). You can check the operation of the door actuator by positioning yourself in the passenger footwell and looking up to the left bottom of the HVAC Unit, where you'll see the actuator/motor. Turn the Mode Selector to any setting, except OFF, on the climate control panel; turn the ignition switch to RUN (without starting the engine); move the temp selector from full blue to full red. You should see the white intermediate drive shaft on the bottom of the actuator move about 90 degrees each way. If you don't see it move, remove the actuator/motor (three fasteners) and with the electrical connector still attached, run it through again with the temp selector. If it moves from stop to stop okay, consider the actuator serviceable. If it won't move, consider the actuator/motor unserviceable and replace it.

If the actuator/motor works okay, try to move the Blend-Air Door pivot shaft by hand or with pliers. If the door won't move, it's jambed.

kevin fravel

Thank you so much for all of the above information. I manually activated the relay by removing the cover to the relay itself, using my electrical tools (I'm an electrician by trade) and making the relay make contact which then activated the fan. Here is an update. I found that my radiator had a leak. I replaced my radiator, the thermostat (195*), and the ETC sensor. When I took my hoses off of the radiator there was barely enough coolant in it to make a puddle on my driveway. Refilled the radiator with 50/50 green anitfreeze. After the repairs listed above were completed my Jeep while sitting at idle goes up to about 210* per the gauge. Doesn't go any higher. I do have warm air now in the cab so I am guessing the door you mentioned is working properly. When I switch the A/C the electronic cooling fan still does not activate. Bigger concern is after letting the engine run and get to 210* twice for about 15 minutes each, I squeezed both the upper and lower radiator hoses and while they were firm (not collapsing) I could still squeeze them in half. I then took the radiator cap off after about a 5 minute cool off and the coolant in the radiator was cool to the touch. Slightly warmer than the outside air temperature of about 45 degrees. I'm not sure what this could be. Also the heat at full hot temp and full blower fan was only warm not necessarily hot !

CCKen

Did you replace the fan relay with a new one?

Did you do the test described above by pulling the connector off the ECT sensor?

If your water pump is the original siince 1999, it may be due to be changed.

kevin fravel

Yes. Sorry I didn't list. I did replace the fan relay. And I did not complete the test with the new relay,as I had replaced the ECT and was hoping that would work. I will do that test today. And yeah I thought the water pump may be bad just wasn't sure. It appears to be factory as the bolts don't appear to have ever been touched. One thought about the water pump. If it is bad wouldnt the engine over heat ? Thanks again for all of your help.

CCKen

You would think so. But because your temp gauge goes no higher than 210*F maybe you should do the instrument cluster actuator test (below) to see if the temp gauge is working properly.

The PCM sends the ECT voltage signals to the instrument cluster via the CCD Bus, where the instrument cluster microprocessor drives the electromecanical temp gauge to the respective indication. If the gauge is bad it will not respond to the instrument cluster microprocessor signals fully. I may not be a bad gauge but the actuator test is free and gets the question out of the way.

During the test pay close attention to the temp gauge.

Instrument Cluster Actuator Test

(1) Begin the test with the ignition switch in the Off position.

(2) Depress the trip odometer reset button.

(3) While holding the trip odometer reset button depressed, turn the ignition switch to the On (RUN) position, but do not start the engine.

(4) Release the trip odometer reset button.

(5) The gauges should cycle through their ranges, stopping at intermediate readings, going up and going down, at two second intervals. The indicator lamps should cycle on and off.

(6) The instrument cluster will automatically exit the self-diagnostic mode and return to normal operation at the completion of the test, if the ignition switch is turned to the Off position during the test, or if a vehicle speed message indicating that the vehicle is moving is received from the PCM on the CCD data bus during the test.

kevin fravel

CCKEN, I completed the gauge test and all gauges went up and down in intervals in unison including the temp gauge. I completed the test on the cooling fan, I pulled the connector off of the ECT sensor, I started the Jeep and low and behold the fan came on I turned the Jeep off. I reattached the connector to the ECT, restarted the Jeep turned the A/C on and the fan did not come on ? And yes I have a 195* T stat and a 16 lb cap on the radiator. Thank you again for all of your help. Still strugglin

CCKen

As far as the fan not coming on when AC is selected goes;

Can you see if the AC Compressor clutch plate is engaging when you select AC? If you're not familiar with this, the clutch plate remains stationary while the compressor pulley is rotating, then when AC is selected the clutch electromagnet pulls the clutch plate against the pulley, which turns the compressor.

Look at the clutch plate in the middle of the compressor drive pully with the engine runnng (stationary), then select AC to see if the clutch starts turning with the pulley. If it does, there's enough pressure available in the Freon system to close the Low Pressure Cycling Switch on top of the AC Accumulator (switch is normally open and closes when system low pressure reaches a preset value). If the clutch doesn't engage the system pressure may be too low, or it's empty. If the clutch won't engage and the fan won't turn on there's a simple test you can do to bypass the Low Pressure Cycling Switch.

See pic below.

Remove the connector from the Low Pressure Cycling Switch and jumper the two pin cavities in the connector using a small paperclip (do not force a large jumper in the pin cavities or you may enlarge them). Make any AC selection on the Mode Selector. Start the engine, the clutch should engage and the fan should run.

If neither work, there's a High Pressure Cut Off Switch located in the discharge tube coming off the Compressor. Its contacts are normally closed and when the Freon system pressure gets too high the contacts will open, shutting down the system The High Pressure Switch is wired in series with the Low Pressure Switch, so if the fan or clutch won't work, remove the connector from the High Pressure Switch and jumper the pin cavities, while the Low Pressure Switch is still jumperd. If the fan and clutch work now the High Pressure Switch is defective and should be replaced.

If only the fan works and not the clutch, the clutch itself, the clutch relay, or its fuse in the PDC may be defective. Check the fuse first to see if it's blown. See PDC pic below.

If jumpering the Low Pressure Switch makes the fan and clutch work, there's a good chance the Freon system pressure is too low to make the system work. It will need to be checked and serviced.

Jumping the Low Pressure Switch.



Clutch relay and fuse.



Do these checks and get back.

Cheers

kevin fravel

CCKEN,

Thanks again for all of the information. The clutch plate on the A/C compressor was not engaging when A/C was selected. I completed the low pressure test by jumping the pins with a paper clip and it engaged the clutch and the electric fan started and ran as well. One more problem solved. I purchased the Jeep approximately 18 mos ago from an individual who said that they had just completed A/C work on it. While it gets warm here in the Summer I don't typically use the A/C as it drops the fuel mileage substantially. Also it is my weekend toy to put around town in and make trips to the grocery store 2 miles and the waste transfer station (dump) 5 miles, versus a daily driver. It apparently has been loosing freon and it just so happens that when I noticed that I had a leak in my radiator that the level got low enough to stop engaging the clutch thus no longer engaging the fan. At any rate I guess now my only concern is this. After I completed the low pressure test as stated above I allowed the Jeep to idle in the driveway until the gauge read 210*. At that point with the Jeep still running I slowly unlocked my radiator cap then slowly turned it to the loose position the the off position and there was not one wave of steam, no pressure (SSSSHHHHHHWWWW) sound at all. Again I stuck my finger in the filler neck to touch the antifreeze and it was not even luke warm. I would imagine if the antifreeze was circulating through the motor that it would be warm and that there should have been some sort of steam and or pressure released when I took the cap off ! Thanks for any more help that you can provide.

CCKen

Each time that you allow the engine to idle and get up to 210*, how long does it take for the temp indication to rise to 210*? Pretty fast?

Does the heater hose coming off the thermostat housing get hot to the touch? Does the heater return hose to the pump get hot as well during this period?

There's a thermostat bypass port in the cylinder head and a chamber in the thermostst housing that accepts the bypass coolant. This chamber has the heater hose connected to it and the ECT sensor is located in this chamber. When the engine is first started, and the thermostat hasn't opened yet, hot coolant will enter the bypass chamber and be routed to the heater core then back to the water pump inlet for fast heater use. If you are seeing 210* you are seeing coolant temp in the bypass chamber and doesn't represent the entire cooling system temp (after the thermostsat opens - 196*F).

A sharp eye can see the thermostat open by watching the temp gauge. Initially the temp will rise to 210* +/- then you will see the temp drop a bit as the thermostst opens, then go back up to 210* +/-.

Try letting the engine run for an extended period of time and keep a close eye on the temp gauge. See if the temp stabilizes around 210*. You should hear the mechanical blade fan start running, but the electric fan should remain off (unless the temp exceeds approximately 218*). If this works okay, drive the Jeep for awhile and watch the temp gauge. When finished with the drive, the coolant in the overflow reservoir should be at the FULL mark, the lower hose should not be collaped, and the upper hose should be too hot to handle. Do not open the radiator cap to test the coolant temp at this time.

If, during the drive, the temp indication shows an overheat and the electric fan is running, you will need to do some maintenance. Suspect would be the water pump or an incorrect thermostat is installed.

kevin fravel

CCKEN,

Thanks again for the information. Sorry for the delayed response. My family and I went out of town for the weekend for a college visit for my son. I will complete these tests today and get back to you when they are complete.