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Discussion Starter #1
ok here is a strange one that started mid road trip. vehicle+ 1993 K1500 Suburban with the 350 /auto tranny/4x4 (do not think it is model suspecific) the suburban has 300990.90 miles and running great, but this last weekend we went on a 300 mile B-day road trip. after the 2/3 of the trip was compleated we stopped for dinner and when we started the burban after dinner it made a clicking sound from low behind the pass heaterbox (sounds like a relay cycling (it sped up last night) or a broken power antenni motor) it last for 30 seconds and now does it when you start the motor and turn off the key both times it will go for 30 seconds and stop. i can drive for any time after and there seems to be no performance issues. the cruse control works all wipers, windows work. we had this truck for 3 months and the only things i done so far was oil,filter and lube and replaced the back-up neautral switch on the steering column. the only thing that gone strang is last month the ac stopped getting the compressor signal so no AC (i was looking into why but the sons Bday trip was right in the middle. any ideas? would this be like the only thread i found the multi function switch? thanks..i am just learning this beast ....mike
 

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That's kind of an interesting one. There isn't really much down there besides the fan, the ECU, and a couple small modules. The flap that regulates the vents (floor, dash, defrost) is in the center of the dash, behind the two center vents.

Any after market installations, like a remote starter, alarm, CD changer?
 

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Discussion Starter #3
the only add in was a Locktronics but the was a the dealership and it is working fine. no other installs stock radio (am/fm does not work) and eq cassette...i got the ipod plugged into the cassette and works fine. i can not think of anything that gets power for the first 30 seconds the key is on and then again 30 seconds after the key is turned off. it is behind the heaterbox and the firewall. it is below the glovebox. it was a steady 1-2 clicks a second for 30 seconds but now it is 4-6 clicks for the same time every time the key is on and when turned off. it is very loud and the clicking can be felt thru the floor and dash but so much on the engine side of the firewall (can be heard but not as strong)..........it just started on Monday morning......mike
 

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Blend door motor/actuator

Googled it cuz a friend of mine has a GMC Jimmy with the same problem. It looks like the issue is a "blend door actuator" read on:

From: Yahoo Answers
I have a 1994 Chevy C-1500 that is making a clicking sound behind the glove box area,what might that be?

The clicking starts when I crank the truck up and last about 15-20 seconds.I hear the same clicking when I turn the truck off and it lasts about the same time.Like I said it is coming from behind the glove box above the heater core.The heater core has not shown me signs of it being bad,no leaking,and no foggy windows.
2 months ago - 6 answers


Answer #1


I've got a 91' Chevy 2500, and I've looked into it in the past.

What's happening is the heater controls are run by little electric motors that open and close vent doors.

When these little motors reach their limit as far as opening, or closing these doors, the "ratchet" on a limit spring so the motor won't burn up.

All that's happening, is the motor is trying to open or close a vent that has already reached its limit of movement.

Don't sweat it. It's kind of normal.

Answer#2
Best Answer - Chosen By Voters


"mr know it all " was close but, not quite right.
The prolblem is a blend door motor, not a relay.........
This is a common problem.
I've replaced several....
 

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I vote for the electric ant. if it has one.
 

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Discussion Starter #6
this suburban never had a power antenni. i research more on the blend door. if i pull the ac fuse this should stop the sound to verify this is the issue? and if this is the case just put the door back in the normal sweep?. thanks i new to this new car stuff. i used to the older vehicles...mike
 

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Discussion Starter #7
ok- here is todays findings and a huge thank you for helping me put my mind to ease. the sound is the blend door. I got in the suburban this morning and as i started the truck the "clicking: started and i hit the "Max" button and it stopped for a few seconds (it then seemed to move and have a different pitch) then i hit the "Max" button agin and it go away and return after a few seconds. so next step is to remove and fix or replace the parts. i post what i find but it will not happen till this weekend.......again thank you...mike
 

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Discussion Starter #8
i went to PNP univerisity this weekend and get some schooling on where and how to swap this part. It is a pain to get to, but i going to try. is the blend door motor the same same as the reare blend door motor and the other door motor on the heater/AC? I was able to get up there and unplug the "Fresh/recycle" door motor plug and the clicking is gone. so as soon as we get a few dry days i try and remove the 2 screws on the motor and swap it out.......thanks for the help.......mike
 

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Take some pics if you can. Always nice to have as much info as possible on a repair. It will help those who follow in your footsteps.:biggrin:
 

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Discussion Starter #10
these may not be the best pictures but the space is small. the motor has a plug that you need to press a tab near the top of the connector and the wires will come right out. here is the motor for the fresh or recycle door. it is located between the blower motor housing and air transport dristribution box. (iff you are sitting in the pass side seat look down below the glove box and on the roght you see a round black and to the left a black square box. inbetween these is sorta a upside down "V" notch this part is in there. it is bolted to the blower motor housing.


here is the new replacement motor. this is the working side or the part that opens and closes the mix door.

the small 7MM screws at at the top and bottom holes the other is a molded pin on the housing.

i hope this helps. you can get in the space with a 1/4" drive and socket or a flexable driver. it is so good to not hear the clicking at the start and end of my trip. this is an easy fix but it can be very frustrating since it is a very cramped space and i not found any books anywhere to show an easier way of replacing this part. again thank you for helping me locate this issue.......mike
 

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Cool! Thanks for the pics. I guess I don't have any excuse not to help my buddy with his clicker now!:biggrin:
 

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Cool. This solves the problem? I didn't see if you said it was not clicking anymore.
 

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Discussion Starter #13
yes i now can turn the key on with no more click-click (30 seconds long) and the same silence when turning the key off. it is so much better to drive no more stares when i pull in a space and power off or on....lol. i used junk yard pards as i was broke but the price was right......This issue has been resolved.....mike
 

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Discussion Starter #14
ok---doomsday time to swap out the bad part. after looking it was not too bad. i had the head light switch go up in smoke so i cut work to fix all that i could. to replace this motor you need a 1/4" ratchet and a 7MM socket (not much else will fit in there. i removed the glove box door and liner (i pulled the light bulb too. the bottom 7mm screw was easy to get out. the top was a pain. i had to feel and see where the top screw was and puch the ratchet up and try to get it on the head i then had to reach thru the top of the unit thru the glove box opening. i used one finger to hold thr ratchet aganst the bolt and one finger to allow the ratchet to ratchet. the unit came right out (2 screws 7mm). here is the new unit.

i knew getting the top screw back in was going to be a pain in the a$$ so i took some vacuum line cut it so it woul hold the screw and fill the slot. this worked great i was able to get the unit back in the space and i had to use my finger and lift the recycle door to align it witrh the motor and it went into place. i tighened the bottom 7mm screw firts. i then had to fish the ratchet up and get it on the head of the 7mmm screw once it was on i put my hand back thru the top of the unit to hold the ratchet on the head of the screw. the rubber put just enough friction i did not have to hold the socket and ratchet the ratchet. ok the reason we had the clicking you ask? i show you.
i remove the 4 screws out of the cover.

here is the insides

if you look at where the 3rd gear meshes with the 2nd gear (from the top) you can see the missing teeth. so the drive motor would skip and make the "Thumper" sound. this looks to be an easy fix sawp out the bad gear and be on the way but it was easier to swap the whole unit.

ok the wrap up - i now have a smooth recycle door that opens and closes and does not make that horrable thumping sound. i too have 4 spare drive motors..............i hope this helps some one else wanting to fix this total time was 2 hours---but sine i know how i bet i can do it in 30min to an hour now......mike
 

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Fixed!

Thanks for the detailed description and the cool pics.
 

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Ok, I know this is an old thread and this is my first post but hopefully someone will find my question. I have a 95 sierra, same problem. Found the little plug to stof the clicking, but can anyone explain why, when my battery went bad is when it started clicking, got new battery, clicking stopped for several months. I used a drop light from my cigeratte lighter that ran battery down, the clicking started again. Same as Mike above, (30 sec when I turn key on, 30 sec when I turn key off). What is the connection there? That part I don't understand. In other words, could it be that not enough power is getting to that motor? When I have heter on and it is clicking, if I push the REC button it stops, but in that position, if I turn the heater/fan off the clicking starts again for the 30 sec.?
Anyone have any imput on this. Thank you in advance :).......Sherrie
 

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Wow, theshop charged me $1600 a few years ago to replace the blend door and recycle door, mostly labor because they had to remove the whole AC system from undwr the dash to replace those doors.
It's clicking again in the blend door. Constant cliclimg if I turn it all the way to cold, which I do alot in the summer. Seeing how relatively easy this is, I'm going to replace this myself this time.
 
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