97 with ATC, only blowing out defrost/feet vents - JeepForum.com
 
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post #1 of 10 Old 08-22-2018, 07:53 PM Thread Starter
demagogue
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97 with ATC, only blowing out defrost/feet vents

Currently my ac/heat is only blowing out of the defrost and driver side floor vent. I have the automatic temp control. I got down under the driver side by the pedals and didn't see the servo motor moving any of the linkage. Also will add there aren't any trouble codes from the ATC.

Has anyone had something similar? Any thoughts if it's possible a wire or something is lose? I plan on looking into it more tomorrow when I have some more light and see if I can deduce what's going on but thought I would ask since I can't find much on the ATC system.


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post #2 of 10 Old 08-22-2018, 08:06 PM Thread Starter
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I guess I could be hitting this TSB assuming it applies to the 97 too. https://workshop-manuals.com/jeep/gr...ding/sticking/

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post #3 of 10 Old 08-23-2018, 08:44 AM
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Been meaning to make a post about this message, as I'm having the same issues.

I don't have a definitive answer for you, but the little bit of research and investigation I did, revealed two possible issues.

One, the switch you've already mentioned, near the right side of the gas pedal.

Two, there's a vacuum line that comes out on the passenger side firewall and runs that side of the vehicle. If this is loose or damaged, the vehicle will stop switching the vents correctly.

Hopefully that'll help. If I come across those resources I found previously, I'll post them here.

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post #4 of 10 Old 08-23-2018, 08:50 AM
PlainoldCheroke
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Vent system need proper vacuum to work correctly

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Originally Posted by demagogue View Post
Currently my ac/heat is only blowing out of the defrost and driver side floor vent. I have the automatic temp control. I got down under the driver side by the pedals and didn't see the servo motor moving any of the linkage. Also will add there aren't any trouble codes from the ATC.

Has anyone had something similar? Any thoughts if it's possible a wire or something is lose? I plan on looking into it more tomorrow when I have some more light and see if I can deduce what's going on but thought I would ask since I can't find much on the ATC system.
FOLKS -- you have vacuum leaks -- first check the little tank ( to hold extra capacity after engine is turned off) -- but vent control system will default to only the defroster outlet if there is a broken hose or anything else causing the vacuum from engine to be lost --- some comb over every single hose starting with the big one where it gets vacuum from the intake manifold

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post #5 of 10 Old 08-23-2018, 11:07 AM
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Nope, none of the ATC system is vacuum operated, it's all electric.

Mode door arm on the ATC is a common failure.


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post #6 of 10 Old 10-13-2020, 04:18 PM
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I am having this same issue.
Gets hot and cold it seems so that rules out a blend door (its TX, its already hot unless its airconditioned).
Blows normal and cold. Great, its just directed onto the windshield and sort of on my gas pedal chin. So just a air navigation issue.
No fault codes with the ATC stickman stuff from this limited snippet, stays at 00 in the fault test. Though, I dont know what all of the 36 test programs are so I cant run those to try and narrow it down that way. https://www.jeepforum.com/forum/atta...j-hvac-bit.pdf

I have found that on the drivers side foot linkage that I can disconnect the bottom clip and pull down on the actuating rod and that switches the air to blowing out the middle vents onto me beautifully. So I think I may just wire it down and keep it blowing on my face until winter.

Defrostposition with it latched in like its supposed to be


Mid face vents, might buy one of those cute little vice grips just to weight it down.


Am I crazy in thinking that this is the motor thats seized up? Could it be anything else? With the rod disconnected the above door moves freely, its the linkage going into the underside of the dash that wont move at all.

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post #7 of 10 Old 10-14-2020, 02:05 PM Thread Starter
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Wow you finding that is a game changer for me, because now I can at least rig something up to get usable AC/heat. I wonder if there's a relay out that controls that motor? Or a fuse maybe?


I'll check next time I get a chance. Per the link below, looks like #12 controls some of the door actuators.



https://fuse-box.info/jeep/jeep-gran...ses-and-relays


1210A/C Heater Control (MTC), Blend Door Actuator (MTC), Automatic Temperature Control Module (ATC), Recirculation Door Actuator (ATC), Driver/Passenger Seat Heater Control Module, Switch POD

Last edited by demagogue; 10-14-2020 at 02:08 PM. Reason: add more info
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post #8 of 10 Old 10-14-2020, 02:27 PM Thread Starter
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Definitely not the fuse.

2002 KJ (Owned 2005-2015, RIP)
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post #9 of 10 Old 10-14-2020, 02:31 PM Thread Starter
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Relevant thread https://www.jeepforum.com/forum/f13/...umber-3360938/

2002 KJ (Owned 2005-2015, RIP)
1997 ZJ Limited
2013 Subaru BRZ Limited
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post #10 of 10 Old Today, 07:49 AM
PlainoldCheroke
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our 1995 XJ is entirely vacuum operated. We plugged the line at the T - on firewall and suddenly the interior vents work in all positions, so ours defaults to the defroster if there is not enough vacuum to operate the other doors-- makes sense as it's most important for visibility. Our cruise control line was the problem -- it had cracked and caused a vacuum leak so the doors defaulted to the defroster.....

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