post #1 of Old 01-05-2011, 10:57 PM Thread Starter
SuperWade2
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Heat Not Very Warm - Newbie 5.9ZJ Owner

Ok, as of last week, I'm a new, first time ZJ 5.9 owner (12 year TJ Owner) and not super technically or mechanically inclined.

I saw mention of some Diagnostics that I might be able to run as a starting point, but no clue how to make that happen.

I can say that the blower is working well, lots of air moving, the Defrost blows air up top like it should and the dash and floor vents do their thing when the dial is on them. The Engine gets up to temp in a normal time as I expect 200-210, and the Radiator Was recently flushed and refilled per the previous owner (the coolant appears nice and new looking green).

I live in NorCal where the weather doesn't get real cold, but we've been in the High 20's overnight/early AM, so it would be nice to have at least some luke warm air, but I'm not worried enough to spend thousands of dollars to fix.

I did some searching (and willing to continue doing so), but was hoping some folks could give me places to start... There are a lot of new terms and things I don't really know where or what they are (Blend Doors, Heater Cores, etc).

Any help, or places for me to start looking would be greatly appreciated!

Thanks
Sw2

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post #2 of Old 01-05-2011, 11:52 PM
jnicewan
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Let the engine warm up, and turn the heater on and after a few minutes feel both heater hoses under the hood. If one is a lot cooler than the other, you might have a restricted heater core. You can disconnect the heater hoses and flush a water through it both ways with a garden hose. If one hose is still cool afterward its probably still restricted and may need a new core.

Im not quite sure you can see the temp blend door or actuator from under the dash, but it might not be moving or could be broken. someone else may chime in here with some more tips hopefully.
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post #3 of Old 01-06-2011, 08:57 AM Thread Starter
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Quote:
Originally Posted by jnicewan View Post
Let the engine warm up, and turn the heater on and after a few minutes feel both heater hoses under the hood. If one is a lot cooler than the other, you might have a restricted heater core. You can disconnect the heater hoses and flush a water through it both ways with a garden hose. If one hose is still cool afterward its probably still restricted and may need a new core.

Im not quite sure you can see the temp blend door or actuator from under the dash, but it might not be moving or could be broken. someone else may chime in here with some more tips hopefully.
Thanks, I'll give it a try later today!
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post #4 of Old 01-08-2011, 03:00 PM Thread Starter
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Quote:
Originally Posted by jnicewan View Post
Let the engine warm up, and turn the heater on and after a few minutes feel both heater hoses under the hood. If one is a lot cooler than the other, you might have a restricted heater core. You can disconnect the heater hoses and flush a water through it both ways with a garden hose. If one hose is still cool afterward its probably still restricted and may need a new core.

Im not quite sure you can see the temp blend door or actuator from under the dash, but it might not be moving or could be broken. someone else may chime in here with some more tips hopefully.
Finally checked the heater hoses going into the firewall... after a pretty good warmup and heater running, the hoses were nearly identical temp, at least to the touch, and neither all that HOT, was warm, but I could touch and hold there without too much problem.

Additionally, no matter what temp I had the dial set inside, it was pretty much the same temp air coming out of the vents. Whether the AC was on down to 56 or whatever, or heat all the way on HI, it was a constant "medium warm" air blowing. Does that help me pinpoint any possible issue?

Thanks
Wade
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post #5 of Old 01-08-2011, 05:03 PM
stephen3776
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Do you have Auto Temp Control (ATC)? Several poosibilities for what could be wrong but from the posts it sounds like a blend door.
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post #6 of Old 01-08-2011, 05:12 PM Thread Starter
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Originally Posted by stephen3776 View Post
Do you have Auto Temp Control (ATC)? Several poosibilities for what could be wrong but from the posts it sounds like a blend door.
I dunno if I have ATC or not, how do I know/check?
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post #7 of Old 01-08-2011, 07:18 PM
jnicewan
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ATC ( automatic temp control ) has the little digital display. Manual A/C is just the 3 knobs. Either system on 98's use an electric actuator/motor to move the temp blend door.

It sounds like you probably have a problem with the temp door or the motor that controls the temp door position. The actuator/motor can be accessed or replaced pretty easy. Its on the bottom of the HVAC case above the trans tunnel, you can get to it from the pass floor side. You might grab a flash light and get to where you can see the motor assy. reach up to the control head and switch the temp knob back and forth from hot/cold and watch the to see if the motor shaft is moving the door. If its not moving I bet the motor is bad. If its moving the door is probably broken.
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post #8 of Old 01-08-2011, 07:26 PM
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The ATC you speak of is standard equipment in the 5.9

5.9 ZJ
add ons: Go fast stuff, Stop fast stuff, offroad stuff, and bright lights.
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post #9 of Old 01-08-2011, 07:27 PM Thread Starter
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Quote:
Originally Posted by jnicewan View Post
ATC ( automatic temp control ) has the little digital display. Manual A/C is just the 3 knobs. Either system on 98's use an electric actuator/motor to move the temp blend door.

It sounds like you probably have a problem with the temp door or the motor that controls the temp door position. The actuator/motor can be accessed or replaced pretty easy. Its on the bottom of the HVAC case above the trans tunnel, you can get to it from the pass floor side. You might grab a flash light and get to where you can see the motor assy. reach up to the control head and switch the temp knob back and forth from hot/cold and watch the to see if the motor shaft is moving the door. If its not moving I bet the motor is bad. If its moving the door is probably broken.
Ok, I have the Digital thing then, i don't have 3 dials...

I'll go out and take a peek once I get the kids to sleep.

Quote:
Originally Posted by NW-XJ View Post
The ATC you speak of is standard equipment in the 5.9
Thanks, I have a lot to learn about the ZJ's...
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post #10 of Old 01-08-2011, 07:47 PM
stephen3776
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If you have the ATC you can push the AC and Recirc button at the same time and it will give error codes. This might help point you in the right direction.
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post #11 of Old 01-08-2011, 09:08 PM Thread Starter
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If you have the ATC you can push the AC and Recirc button at the same time and it will give error codes. This might help point you in the right direction.
Using this FAQ - http://www.jeepforum.com/forum/f13/a...ostics-106446/

I got a Code 23, which I don't really understand.
23......... PCM message missing.....................Collision Detection C2D BUS Inputs

Any idea what to check next?
Quote:
Originally Posted by jnicewan View Post
It sounds like you probably have a problem with the temp door or the motor that controls the temp door position. The actuator/motor can be accessed or replaced pretty easy. Its on the bottom of the HVAC case above the trans tunnel, you can get to it from the pass floor side. You might grab a flash light and get to where you can see the motor assy. reach up to the control head and switch the temp knob back and forth from hot/cold and watch the to see if the motor shaft is moving the door. If its not moving I bet the motor is bad. If its moving the door is probably broken.
Laying on the pass floor, looking up under the dash at the trans tunnel, and I don't see anything that looks like a door or something that opens and closes...do I need to remove stuff to see what I'm supposed to be looking at?
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post #12 of Old 01-08-2011, 09:25 PM
stephen3776
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If I am reading your post correctly you have a 98 ZJ and the reference
http://www.jeepforum.com/forum/f13/a...ostics-106446/
is for a 99 ZJ. An error code 23 on a 98ZJ is Door Travel Range to small (Blend Door Actuator Drive Circuit). This could be wiring, stuck door, bad actuator, broken arm to blend door.
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post #13 of Old 01-08-2011, 09:32 PM Thread Starter
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Quote:
Originally Posted by stephen3776 View Post
If I am reading your post correctly you have a 98 ZJ and the reference
http://www.jeepforum.com/forum/f13/a...ostics-106446/
is for a 99 ZJ. An error code 23 on a 98ZJ is Door Travel Range to small (Blend Door Actuator Drive Circuit). This could be wiring, stuck door, bad actuator, broken arm to blend door.
Yes I have a 98, and the Link showed errors for both 98 and before and 99+, and I though I was looking at the right chart, but will look again, thanks for helping me with this too... I really appericiate it!
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post #14 of Old 01-08-2011, 09:36 PM
stephen3776
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No problem as I know what your are going through, just had to backflush the heater core on my 93 ZJ. I have to say thanks to NewfieZJ for pointing me in the right directions for figuring out what is wrong with heater systems.
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post #15 of Old 01-08-2011, 10:02 PM
jnicewan
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Sorry I dont have pics, but that temp actuator can be hard to see, you will probably have to adjust the carpet a bit to get to it. It should be held on by a couple phillips screws, you will need a angled screw driver to get them out. The motor will need to drop straight down to remove. Also there is a link between the motor and the shaft on the door that can break too. There are companies that make metal links to replace the cheap plastic one too (if its broken)

If you can picture where the heater core is in the HVAC box, the motor is right beside the core.
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