• 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.

AC / Heat Problem

B

BlueZombie

NAXJA Forum User
Location
Missouri
Hello all,

I posted a while back about my air only blowing hot and I wasn't getting any cold air. People suggested that it might be the blend door, but that seems to be fine. I can change the blend door one way or the other with my hand it it will change from hot air to cold air.

Upon further inspection, I checked the blend door motor and it seems like it's not getting enough power. When I change the temperature knob on the dash, I can see the gears inside the actuator turning one way or the other, based on which direction (hot/cool), but they just barely turn. I purchased a used motor off of ebay and i'm getting the same problem, so I am fairly confident that the motor is fine as well. This leads me to believe there is some sort of electrical problem where the motor isn't getting enough power to it to turn the gears, in turn moving the blend door one way or the other. I have checked the connection to the motor and it seems fine (no loose wires, and it's plugged in securely).

What would you guys recommend I check? Has anyone else experienced this problem. I own a 2001 XJ.
 
Take the motor off the housing and work the control. With a good actuator (blend door motor), you won't be able to stop the motor with your fingers. If you can stop it, try wiring it directly to your battery and see if you still can stop it. You probably have some other problem with the control unit (where the knob is in the dash). Actuators don't go bad very often.
 
Hey all,

Thanks for the replies. I actually purchased the heater treater a while back to try to fix the problem and was following the instructions when it said to test the motor out, this is when I discovered that the motor wasn't functioning properly. All gears/teeth look fine on both of the motors that I have. My main problem is when I turn the temperature knob, the gears move slightly and then stop. I also tried lubing them up, but I don't think it's a gear/lube problem as both motors do the exact same thing (slighly move when turning temp knob).

All signs point to the motor not getting enough power to turn the gears, which in turn would turn the blend door. Is there some sort of resistor that I should check? I checked the #25 fuse and it is ok. I'm stumped.
 
Sorry, no resistor. Since you have the problem on two different actuators, and the motor does turn a little when you turn the temp knob, you have a high likelihood of having a bad control head. That is the panel with the switch in it. I'd change that out. They are impossible to test except by the original manufacturer of the control head with special equipment. That part should be pretty cheap on ebay or craigslist. FSM says to disconnect the stuff from the back of the panel by rolling down the glove box door and reaching around.
 
Thanks for the help winterbeater. Is that the exact name of the part? I'm having a heck of a time finding one on ebay or using google for that to find it. I suppose I could also try a new motor, since both of the ones i've tried are "used". I just have a hard time thinking that both are bad. So you're talking about the panel with the 3 dials on the center dash (one controls fan speed, one for temp, one for vent location)? I suppose that makes sense, but never thought that would go bad!!!
 
Could be. The blend door uses an stepper motor. Turn the dial a little, the door move a little. Turn the dial a lot, the door move a lot. It's certainly possible you got 2 bad actuators but I'd also start leaning towards the control.
 
Went to ebay. Just searched Jeep Cherokee heater. And to make sure your actuators are good, just hook them up to your battery directly. Or we used to test them using a little 9V transistor radio/smoke detector battery. Hook it up one way, it should run strong, switch the wires, it should run the other way. The controls are complicated as they have to sense the clocking of the motor, or they will just break the door with their force. Different vehicles use different styles of feedback to sense the range of travel of the motors and the doors.

http://cgi.ebay.com/ebaymotors/HEATER-AC-CONTROL-99-00-01-CHEROKEE-W-AC-GUARANTY_W0QQitemZ310138908728QQcmdZViewItemQQptZMotors_Car_Truck_Parts_Accessories?hash=item4835b83038&_trksid=p4506.c0.m245&_trkparms=65%3A1%7C39%3A1%7C240%3A1318
 
Awesome I can't thank you enough. I tested both motors with a 9v and both run strong still. I'll search some auto salvage places locally and if not, order that one off of ebay.

I hope she's fixed after that...it's getting humid here.

Thanks again
 
Well shoot...I got the control head unit in the mail and hooked it up. Still no luck. I'm clueless as to what it could be now. Both motors I have were tested with the 9v and they worked in both directions. I replaced the control head. I'm thinking i'll just bring it into the dealership and maybe they can troubleshoot it.
 
I just had my AC fixed last week and a new evap was installed. When finished, found out the blend door has slipped out of its track within the case. When it warmed up from the heater, it expanded just enough to stop if from working, in the cool morning it worked fine. Your blend door may be off of its track and the motor doesn't have enough power to move it. Bad news is that the evap case needs to be dismantled, and dash, to fix it.
 
Have you checked fuse 22 in the interior fuse block near the passenger kick? This feeds the actuator? Check orange wire going into actuator for constant 12V (actually this wire changes from dark brown/white to orange at the actuator plug). Check dark brown/white wire going in to control head for constant 12V. Dark brown/white wire out of actuator (changes to black at plug) needs to go to ground and black wire out of control head needs to go to ground.

Do you need more help on how to check this stuff? Do you have a voltmeter? If not, they are way cheaper than even driving past the dealership.
 
I checked fuse 22 and it is ok. I also checked 25.

I toyed around a little more with everything and here is what I found. When I take the cap off of the actuator to expose the gears/motor, there is the 6 pins on the circuit board. When I plug the connector (3 wires black/red/yellow *i think*) half way on to the 6 pins from the circuit board, the gears move real strong. I can rock the connector back and forth and gears will change direction. Once I fully plug the connector in to the 6 pins, the gears don't respond.

When I turn the temperature knob on the dash, the gears move maybe 1 millimeter and that's it. No constant power...

I do have a multimeter, but don't know how to use it. How do I check that the wires that you mentioned are grounded and also check for constant 12v?

Thanks again...appreciate everything so far.
 
Last edited:
winterbeater said:
If you plug in the actuator without it being screwed to the housing and turn the temp knob back and forth, the motor only moves a very small amount?
Click to expand...

That's correct, the gears will move very slightly...like a millimeter each way depending on whether I move it to hot or cool. They move slightly and then stop.
 
Did a little checking with the multimeter. Here is what I did...hopefully I did it right.

I put the black prong (multimeter) to black wire (actuator plug) and red prong (multimeter) to orange wire (actuator plug) = multimeter reading was 12.0

I then checked the plug that goes to the temperature control knob on the head control. There is a black wire, red wire, blue wire. I put black prong (multimeter) to black wire (temp plug) and red prong (multimeter) to red wire (temp plug) = 12.0. The same goes for when I touched the red prong to the blue wire on temp plug (12.0).

There is also the main plug for the control head. I didn't see a brown/white wire though. There are 7 wires going to that plug (3 large wires and 4 small wires). I checked all of them using the black wire for ground, 5 of the wires tested at 12.0 and then there was the small orange wire which looks similar to the one that's on the actuator plug, this wire was 0.0

Let me know if I did anything wrong and what you gather from that info.

Thanks
 
You must log in or register to reply here.

Similar threads

tjmotter
Heater box repair - pics needed
Replies
1
Views
1K
75SV1
7
E
CA smog issue "Minimum voltage not detected"
Replies
13
Views
985
Johnnie Walker
Johnnie Walker
O
2000 XJ Failed Colorado Emissions high CO
2
Replies
27
Views
2K
Ken M
K
V
High temp woes
2
Replies
21
Views
413
Vitzaa
V
P
AC Compressor Only Engages When Relay is Jumped
Replies
10
Views
3K
Irene6A
I
Back
Top