A common problem is to find one day when moving the climate control knob on your 98 Blazer to the cold position and tap the A/C button you get still hot air and hear a *creak* *pop* from under the dash. So now what? Well, chances are it's the blend door motor, the unit that moves a blending door in a duct behind the dash on the passenger side that moves anywhere between cold and hot, corresponding with your temperature knob.

We were able to get the one in our 98 Blazer out by dropping open the glovebox and using some small tools.

Pictures:

Picture 1, the electronic blend door motor
http://img70.imageshack.us/img70/1665/img02053uo.th.jpg (http://img70.imageshack.us/my.php?image=img02053uo.jpg)

Picture 2, the blend door taken apart, by removing the 4 small screws
http://img70.imageshack.us/img70/478/img02077ig.th.jpg (http://img70.imageshack.us/my.php?image=img02077ig.jpg)

Picture 3, The Problem, the broken gear.
http://img70.imageshack.us/img70/3673/img02085ec.th.jpg (http://img70.imageshack.us/my.php?image=img02085ec.jpg)

Why the gear breaks I am not sure. The door itself does not seem hard to move.

More to come later, such as pictures of where it is located.

Currently, the blend door itself in the Blazer is tied to the cool position so the A/C works.

:thumbsup: Good stuff

the reason it breaks is becouse of the material it is made out of, Tephlon is not very durable. I had to replace mine not too long ago, I tried doing the quick fixs and even went to a bone yard to get a used one and that was a flop too, I ended up going to a dealer and spending about 200 bones for it, I checked the numbers and asked why they were different. the dealer called the manufacturer and they said the numbers were different becouse the part was an upgrade, the gear is supposed to be made out of aluminume now. Ive been happpy so far. oh by the way, good post, and if the moderators want they can combine my post on this issue with this one....

Is this the same motor used in the automatic temp control?

Nice write up, thanks.

Is this the same motor used in the automatic temp control?
Yes, this came out of our 98 Blazer that has an automatic temp. control.

KILLER WRITEUP DUDE! WITH PIX!

I've been suffering with this issue for a while. Did you replace the full motor or just the gear?
What small tools you used to get to it? It's VERY difficult to reach the three mounting screws.

http://i16.photobucket.com/albums/b40/JoshB_/relay2.jpg

KILLER WRITEUP DUDE! WITH PIX!

I've been suffering with this issue for a while. Did you replace the full motor or just the gear? And where did you order it from? Cost?
Could you give me the details on the part number for the new motor, and what small tools you used to get to it? It's VERY difficult to reach the three mounting screws.

http://i16.photobucket.com/albums/b40/JoshB_/relay2.jpg

What view is this?

Ok, I just ordered the new blend door motor for the AUTO Climate Control on my 98 Blazer LT. They call the part out as an "ACTUATOR", and it appears as #4 in GM's exploded view.

The new P/N is 89018365

The dealer priced is at approx $180, I got mine from GMPartsDirect.com for:

SUB TOTAL: $97.58
SHIPPING: $21.47
TAX: $0.00
TOTAL WITH TAXES: $ 119.05

Eye level looking through the glove compartment area with the glove compartment flipped open and down out of the way.

I may have to do this, I am having the same issues.

SHIT! I bought my replacement motor, but I'm still having the problem. I have NO movement whatsoever in the motor at this time. Not in the old or new motor. I've checked fuse number 21 in the fuse block on the drivers side dash, and the HVAC fuse under the hood. I'm stumped. What's the problem? Anyone?

Below is the schematic....any help would be GREATLY appreciated. Otherwise I may end up paying the dreaded RIPOFF $90 Diagnostic fee.

http://i16.photobucket.com/albums/b40/JoshB_/98blazer_Page_1.jpg

GM PARTS DIRECT sent me the WRONG DAMN PART! They sent me the actuator for the Manual not the AUTO! No wonder it's not moving, it doesnt have the correct number of pins to receive power!

Auto part:
http://img70.imageshack.us/img70/1665/img02053uo.jpg
-------------------------------------------------------------------
Manual part:
http://i16.photobucket.com/albums/b40/JoshB_/wrongpart.jpg
as you can see it's a different pin setup from the part shown above.
-------------------------------------------------------------------

I called GMPartsDirect, but its all automated. Best you can do is leave a message. I'm so pissed off!

Well, I've been in touch with GMPartsDirect by phone, and they've shipped me the correct part. They admitted to their mistake, and are going out of their way to make up for it. Very promising! The correct part is on the way and should be here today or tomorrow. I will post a HOW TO with photos on the replacement.

If you have a volt/meter and a schematic with a little patience, (which I lack alot off) i am sure you can figure it out. as for the dif pin setups, you got the wrong part, the dealer part will have most of the original part numbers with a few that are diffferent. looks like you got one for a 2000 model. its got to be a R series.

OK, I didnt do a HOW TO with photos or anything, as I didnt have time when I installed the new motor, so I'll just give you a quick FYI on things to keep in mind. Refer to this photo for the following info.

REPLACING THE TEMP ACTUATOR ON A 98 CHEVY BLAZER 4X4

http://i16.photobucket.com/albums/b40/JoshB_/relay2.jpg

1. Disconnect battery cable.
2. Open glove compartment, and lift tab in upper left corner to allow the glovebox to swing down completely towards the passenger floorboard.
3. Gently remove the line that enters the "Vac Unit", and then the "Vac Unit" itself by wiggling it upwards off its mount. Once removed gently swing it towards the drivers side and out of your way.
4. You now have access to the Temp Actuator.
5. Carefully remove the electrical connector that feeds the Actuator.
6. Using a 1/4" drive wratchet, and 7/32" socket, remove the two (2) mounting screws. (HELPFUL HINT: For maximum ammount of clearance, Keep the wratchect handle facing the drivers side when putting it in place.)
7. There is no screw on the back mounting post, just a pin that holds it steady.
8. Once you've removed the screws you may need to gently pry the Actuator up off the blend door with a screwdriver.

Installation is reverse of the Removal. The Blend Door and Actuator are both keyed, so theres only one way to put it in. Guide the Actuator onto the Door, then re-secure the mounting screws.

I created account to thank y'all for this. I realize this is an old thread and I've not looked into it yet, but there is an access panel under hood labeled "Cut here for service" that was mentioned in another thread I had found, for which I do not have a link. I believe that is the easier way to get to that actuator. I'll post back for the archives this weekend.

Thanks again.

The "cut here for service" you are referring to is for blower motor replacement. The blend door actuator is only accessible from under the instrument panel.

Just wanted to add to the thanks on the best information I have found on this subject. I wish I had found this sooner since I dropped my Dash last night to get the motor out. Yep the gear was broken, and Oreilly's autoparts has it for $34.00.
This one thread was worth the time for signing up.

Hey !
My 98 Blazer the actoator moter doesn`t stop . It moves back and forth without anything and in any outher slection ????
Help !!!

I have a 96 S-10 and I was wondering, do I have to take out the entire dash to get to the blend door unit? it seems like the glove compartment is attached to the dash.

http://www.conquestauto.com/servlet/the-1299/New-GM-AC-Actuator/Detail

109.00 free shipping

Billy

How did you get to the 2 screws on top of the blend motor? Is this the same as a 99GMC Jimmy? I dont recognise the pics even though I have all my dash panels off tring to get at this mistery motor. Please help:banghead:
Thank you Dan 612-685-6586

There are two more actuators to the left of the one discussed here. #19 and #17 on dealer print out. I have every bolt I can find out of my dash and still can't move that black plastic piece that is hidding the two acutators. Need help on getting to the actuator.

Hi,
nice witeup in the works.
MY wife's 2000 Envoy has the same problem...blows hot air. A/C lines are cold.
My first suspect was the blend door actuater.
I replaced one on a Ford Windstar and what pita!!@!!!!!!!!!

Do you have more details on the swap/replacement procedure?
Thanks,
jonny

Hi,
nice witeup in the works.
MY wife's 2000 Envoy has the same problem...blows hot air. A/C lines are cold.
My first suspect was the blend door actuater.
I replaced one on a Ford Windstar and what pita!!@!!!!!!!!!

Do you have more details on the swap/replacement procedure?
Thanks,
jonny

Sorry..never got to page 2.
Anyhow..is a 2000 envoy the same?
I guess I'll have to dig into it tomorrow.
Thanks again.

2. Open glove compartment, and lift tab in upper left corner to allow the glovebox to swing down completely towards the passenger floorboard.
3. Gently remove the line that enters the "Vac Unit", and then the "Vac Unit" itself by wiggling it upwards off its mount. Once removed gently swing it towards the drivers side and out of your way.
4. You now have access to the Temp Actuator.
5. Carefully remove the electrical connector that feeds the Actuator.
6. Using a 1/4" drive wratchet, and 7/32" socket, remove the two (2) mounting screws. (HELPFUL HINT: For maximum ammount of clearance, Keep the wratchect handle facing the drivers side when putting it in place.)
7. There is no screw on the back mounting post, just a pin that holds it steady.
8. Once you've removed the screws you may need to gently pry the Actuator up off the blend door with a screwdriver.

Installation is reverse of the Removal. The Blend Door and Actuator are both keyed, so theres only one way to put it in. Guide the Actuator onto the Door, then re-secure the mounting screws.

Thanks!!! Did just that..have part in hand and looks identical to yours..with crack in gear.
O'reilly can't pull up the auto one's price......nor is it available "on-line".

Junkyards or another cheap avenue now.
This was SIMPLE compared to the Windstar I did once!

Thanks for the write up...saved me hours!!

First off thanks to everyone for the information. Hope someone can help with a quick question. on my wife's 2000 jimmy there are several vacuum actuators above the accelerator pedal with color coded vac hoses to them. They seem to function doors that direct the air to the different vents. One has a red and blue hose on the same actuator, another has a single yellow and one with a single black. I also found a brown vaccum hose that looks like it goes to one of the actuators but cannot find one with an unused nipple that it may have come off of. Anyone have any insight as to where it may belong?

second question, The problem I'm trying to fix is that the air blows neither cold nor hot air but just luke warm. Pep boys diagnosed it as a blend door issue, but most people on the forums complain of either really hot or really cold air all the time. Is there only one blend door? and if so is there a position in which it may be stuck that would blow room temp air only? (when set to heat or A/C)

Thanks in advance.

I have the problem with no heat and the temp of the air never changes. I have the 2001 blazer with the trailblazer package. I have replaced blower motor and thermostat and heater core and all is brand new. I have checked fuses and nothing. I am hoping this is the key to keep me from freezing is there anyway just to make the air hot all the time instead of just buying the new part. If soo please let me know if I can do a quick fix or if ill be stuck paying to replace this over priced piece.

I too need to replace the temp actuator motor on a 96 s10 and as notsmartguy states above, access behind the glove box is blocked by the dash (no opening). Has anyone changed a 96? Does the entire dash need to be removed or is there another way??

I too need to replace the temp actuator motor on a 96 s10 and as notsmartguy states above, access behind the glove box is blocked by the dash (no opening). Has anyone changed a 96? Does the entire dash need to be removed or is there another way??


Yes, I think so, on my 95 I have to remove the dash, or at least loosen it and pull it back about a foot to get room to get to it... no removable glove box there...:banghead:

/Freddy

New guy here...

There's a rumor floating that there is new software available so these actuators don't lose position and wreck themselves. Has anyone heard this?

Mine was cycling both ways upon cycling the ignition. It's -6 degrees here so I just got done turning the key on, waiting till it cycled one way and then unplugged it so at least I have heat for the winter.

What are the initial proceedures when replacing this with the new one? Can it just be replaced or is there a sequence or fuse-pull operation to go through? I don't need to wreck another one...

Dealer Quote:
Part $238.59
Labor 5 hours. dash has to come out.

$729

Fixing it myself:
Part $100.
32 minutes, not 5 hours, for me to change. I'm not a certified ASC GM technition so obviously I did it wrong. Take the dash out.... You'd have to be stupid!

Awaiting response before rurning key...
Thanks in advance!

Hey Guys,
I had the same problem on a 2000 GMC Jimmy (Chevy Blazer)
Set on Heat, it wanted to blow hot air for a few seconds, then went to lukewarm and made little different to the chill of the cool temps outside the vehicle.

Following the instructions I found here, I went out and pulled the 15 amp fuse in the corner of the fuse box (located in the side of the dash on the driver's side - look where the door meets the dashboard) that is listed for BATT. After leaving it out for a few minutes, I had to reset the clock on the radio, and hot air seemed to flow consistently.

Please do this before attempting any elaborate repairs to the actuator. It's a lot easier.

Also, please note that the glovebox can be dropped all the way down on this vehicle, but that I do not believe the hot air actuator blend door is located in the same place as earlier models. (at least, I was unable to find it via the pictures given previously)

Before buying a new blend door motor assembly, try and FIX IT!

My mother has a '94 Oldsmobile 88 that had the same problem with the broken gear. The blend door motor assembly looks just like the one posted here. I made a REPAIR on the assembly this morning without having to purchase a new part. I thought I would pass this on, maybe someone can fix theirs also and save a few bucks.

When the large gear cracks and the crack rotates to where the smaller gear contacts it, the gear loses contact and the arm stops. Not all of the large gear is used when opening/closing the blend door. Only about 45% (a guess) of the gear is used. Just remove the gear from the metal shaft and rotate it to where the crack is in an area where it won't ever come in contact with the smaller gears then press the gear back onto the shaft.

Be sure and make note of what the actuator arm position is before removing it. Also, the metal shaft that the large gear presses on has stops on it. The stops are on the bottom of the plastic housing. Make sure you get everything lined up like it was before you disassembled it. I had to plug my assembly in with the top of the case removed and adjust the temperature control slowly to make sure I wasn't going beyond the stops before putting it all back together. I took the opportunity to put a small amount of silicon grease (light bulb grease) on the gears before putting it back together. The assembly works great now, just like brand new!

Mike Z.

Before buying a new blend door motor assembly, try and FIX IT!

My mother has a '94 Oldsmobile 88 that had the same problem with the broken gear. The blend door motor assembly looks just like the one posted here. I made a REPAIR on the assembly this morning without having to purchase a new part. I thought I would pass this on, maybe someone can fix theirs also and save a few bucks.

When the large gear cracks and the crack rotates to where the smaller gear contacts it, the gear loses contact and the arm stops. Not all of the large gear is used when opening/closing the blend door. Only about 45% (a guess) of the gear is used. Just remove the gear from the metal shaft and rotate it to where the crack is in an area where it won't ever come in contact with the smaller gears then press the gear back onto the shaft.

Be sure and make note of what the actuator arm position is before removing it. Also, the metal shaft that the large gear presses on has stops on it. The stops are on the bottom of the plastic housing. Make sure you get everything lined up like it was before you disassembled it. I had to plug my assembly in with the top of the case removed and adjust the temperature control slowly to make sure I wasn't going beyond the stops before putting it all back together. I took the opportunity to put a small amount of silicon grease (light bulb grease) on the gears before putting it back together. The assembly works great now, just like brand new!

Mike Z.

This might work... Don't forget the blue gear running off the main drive gear connected to a potentiometer that signals position and location back to the system. This gear is timed in relationship, and if that relationship is lost, nothing will work correctly.
The reason these gears break is over time the plastic part that was either over-molded or pressed over the metal core, is strained due to the tight fit. It usually cracks because the material dries out. This is common for nylon and acetal materials. Repositioning the gear doesn't fix the crack and the "fit" between the metal and plastic gear meaning that the core will slip again in the future. You might try epoxying the core and the gear, but both are probably short term fixes.
Good luck.

I don't know if the blend door motor or gear is my problem or not. Replaced the battery on my '98 Blazer and now it runs cold and then hot. I do have the ECC on my unit. I took the RAD fuse out and waited one minute and still no luck. If it is the blend door can I get it to a position where it is cooling and unplug it at that time? I don't know if I can even unplug the motor it is so close in there.

Any "tricks" to removing the Vac Unit? Having a hard time getting mine to come off.

Hi All, i have a mitsubishi Verada which i think the Blend Door Motor has gone, i have had this constant ticking noise so i took it to a mechanic $100 to tell me he can't find the fault so i replaced the battery as the light was on $350 still clicking took it to an air con expert $200 just to tell me the blend door motor needs replacing and i am up for $400 is there a cheaper way of fixing or replacing HELP!!!:confused:

I had this problem with my daughter's Blazer It was a 99 with the automatic system. I did tons of research trying to find the problem. The problem originated because the heater core plugged up. This is a common occurrence in these due to the problem with the orange antifreeze (dexcool) that they use. This is such a huge problem that GM should have taken it on the chin and recalled all vehicles and fixed them. Evidently, it's really a problem more with the Blazers due to the mismatch of metals, corrosion, etc. My suburban had Dexcool, and only suffers minor problems due to its past (I've since replaced it, but it still has radiator problems and I still find mud in it.)

So the first thing you have to do is make certain that the heater core is flushed out well. Do that by simply removing the hoses it at the firewall on the engine side, and using a garden hose flushing both directions. I eventually ended up having to replace the core in this one because the dexcool had created a clay-like substance that came out in a blob, and it had corroded the core. You'll be shocked when you see it. So, without the core working properly, the auto heater control tries to drive the door further open when you turn on the heat, figurring that it's not getting enough heat because its not open enough. That then drives the door beyond the end of its normal travel, and it gets stuck- yes it clicks, etc, but it's past the gear movement range, and can't find its way back.

So- next move- go to your Chevy dealer and find the service bulletin that is written on setting the range properly on a newly purchased motor. Note that if you replace the motor, you also have to use this method. It took a bit of digging at the Chevy dealer to find it, but one of the recalled it, and found it. I don't have it, but I recall it involved taking the connector off, and jumpering the motor so that it drove it to a middle-position. I then reconnected, and voila, it now finds its own position using the sensors.

So, in my case, it was a problem of combined failures, and took these two steps to fix it. It took a long time, because I discovered the heater plug in the winter. Then, when I unplugged it, it had all the heat you could stand, and made up for it by turning the fan speeed down. So, it was not noticed that the door was not adjusting. Then, when spring arrived and we tried the A/C, it would not cool. Then after fixing the motor, the core started leaking due to the corrosion caused by the dexcool plug in the core. You've never had fun until you've pulled the entire dash off one of these units to replace a simple small heater core!! You mnight think twice about unplugging the heater core. Ugh. I still have bad dreams, and I think these scars on my arms came from that. It could have been the spark plugs on the Aerostar, but it all starts to blend a few year gone.

Hope this helps.
smapple

Here's mine:

http://img.photobucket.com/albums/v448/therealsundance/DSC00248.jpg


I noticed that after I removed it and pluged it back in it would cycle to the cold position and then move back to the hot position. Maybe the control board is fried.

By the way, to get it out I used a socket to lossen the screw and then a socket that fits into a cordless drive and used my had to unscrew the screws. Eaiser than using a socket.

http://img.photobucket.com/albums/v448/therealsundance/DSC00251.jpg

http://img.photobucket.com/albums/v448/therealsundance/DSC00250.jpg


Old on left, new on right.


Went in and works perfectly. Gotta love ebay.