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Discussion Starter · #1 ·
New here, so I apologize if this subject has been breached at another location. A search of the forum couldn't find anything. My 2015 GMC Terrain SLT will blow air through the defrost vents, and through the floor vents but will not blow from the front vents. A Google search suggests something called a 'Blend Door Actuator'. What is that, and is that the problem or am I missing something else? Thanks.
 

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2011 Equinox 1LT V6 3.0L FWD 174.6k miles
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@MalibuEd : I’m not near my manuals, but the Blend Door Actuator is just a cigarette-pack-sized box with an electrical connection that moves a “door” to blend your heated air (from the heater core) with outside air to control air temperature. It’s controlled by the blue & red temperature knob. As you turn this knob (or change the setting via a screen control), the door moves accordingly.

Your problem sounds like the mechanism that directs the air flow (blended or not) to one of several destinations. Not sure how the Nox system works. On my other cars it’s vacuum-controlled.

UPDATE: it’s called the Mode Door.

See this old thread:


Watch out on the replacement part. There are apparently two generations. That guy had a 2013 Terrain and incorrectly ordered the first gen (with different connections). Sounds like you need the 2nd gen ... even though the Terrain was just a 1st gen vehicle from 2010-2017. Confusing.
 

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Discussion Starter · #3 ·
@MalibuEd : I’m not near my manuals, but the Blend Door Actuator is just a cigarette-pack-sized box with an electrical connection that moves a “door” to blend your heated air (from the heater core) with outside air to control air temperature. It’s controlled by the blue & red temperature knob. As you turn this knob (or change the setting via a screen control), the door moves accordingly.

Your problem sounds like the mechanism that directs the air flow (blended or not) to one of several destinations. Not sure how the Nox system works. On my other cars it’s vacuum-controlled.

UPDATE: it’s called the Mode Door.

See this old thread:


Watch out on the replacement part. There are apparently two generations. That guy had a 2013 Terrain and incorrectly ordered the first gen (with different connections). Sounds like you need the 2nd gen ... even though the Terrain was just a 1st gen vehicle from 2010-2017. Confusing.
Wow. Thank you. I appreciate that. Evidently I would have ordered a part I didn't need that is (hopefully) already working perfectly. I have not taken it to the dealer to have that checked, but I guess I will. I'll let the dealership take care of that. I don't pretend to know anything about fixing cars beyond changing a tire. If God had intended me to fix cars, he would have given me a shirt with my name on it. Actually he did, but I ended up the school custodian.
 

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Do you know if this would be covered under warranty? I would think not, but admittedly- I’m not well-versed in what’s covered and what isn’t. Maybe someone else here will chime in...

If it’s not going to be covered, there’s little reason to take it to the Dealer (IMO). I do not believe this repair requires any special expertise, but that would depend on whether the Mode Door requires recalibration or reprogramming.

Again, someone here with access to the Manuals should be able to answer that question.
 

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Can you bench test the actuator?
Good idea but they are about $25 new, for the effort it takes to RandR it I would put a new one back in.
There are three door actuators (don't know if the OP has an auto or manual HVAC system) so make sure you are working on the bad one.
A scanner with bidirectional controls can test the actuator on the vehicle.

Colt: Yes the new one needs to be calibrated, no scanner necessary, and the OP is probably out of the 3 year BtoB warranty.
 
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It is not really a hard job to change an actuator motor. Watch a few u-tube videos and be ready for a sore neck after laying upside down with your legs hanging over the front seat. Ok I am lying it is a PITA but so is paying for a dealer $100/ hr to do a job you could have. Good luck which ever you choose.
 

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Do you know if this would be covered under warranty? I would think not, but admittedly- I’m not well-versed in what’s covered and what isn’t. Maybe someone else here will chime in...

If it’s not going to be covered, there’s little reason to take it to the Dealer (IMO). I do not believe this repair requires any special expertise, but that would depend on whether the Mode Door requires recalibration or reprogramming.

Again, someone here with access to the Manuals should be able to answer that question.
Have a problem with the vents not working? The problem is the Blend module directly above the gas pedal it is malfunctioning and it is not hard to replace, I will say it's a bit tricky to get to it but it can be done. Remove the two panels under the steering column and under the metal plate you will see a computer module right above the gas pedal, remove the two bolts which are 10 millimeter pull the computer module down and then remove the small cover plate the computer was attached to 3 bolts pull plate down then you will have access to remove the blend module easy to do if you want to save yourself some money. I did however had to disconnect the car battery and leave off for a minute or more, then reconnect battery to reset the actuator which then worked fine. The blend or mode actuator requires to be reprogrammed after complete installation and by removing the battery cable you accomplish that (simple). Hopefully you've saved yourself a lot of money. I'm disabled and i have full confidence that you can do this.
 
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