Blend door actuator - AC Auto Repair Help Forum


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Blend door actuator

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clchris_80
New User

Dec 21, 2005, 8:15 AM

Post #1 of 3 (5128 views)

Blend door actuator	Sign In

Does anyone know where I would find the blend door actuator on a 1997 chevy blazer. My heater and AC will not switch off of the defrost. After much searching on web forums I am pretty sure that it is the blend door actuator but instruction on how to get into it or for that matter what it looks like are non existant. Any help or suggestions on the matter would be very appreciated. That you in advance.

DanD
Veteran / Moderator
DanD profile image

Dec 21, 2005, 11:50 AM

Post #2 of 3 (5124 views)

Re: Blend door actuator	Sign In

I don’t think it’s the blend door actuator that you want, if it is you’ll find it on top of the heater case. You will have to remove the instrument panel to get at it.
But the bend door is used to mix (blend) cold and warm air together to adjust the temperature of the heater not where the air is directed.
The mode control is operated by vacuum through the mode switch and vacuum motors. Most of the time when a customer has the same complaint as yours we find that it’s a broken vacuum line under the hood.
Have a look around under the hood and you should find a vacuum reservoir, it’s usually a round black ball about 5 or 6 inches in diameter. You should have vacuum to it from the engine as well as vacuum leaving it to supply the heater controls (engine running). You may end up chasing the line(s) all the way back to the heater controls, to confirm you have a vacuum supply to the control. These vacuum lines are made out of hard plastic tubing that become brittle with time and take nothing to crack and cause a leak.
You can patch repair these lines with pieces of rubber vacuum hose just make sure the rubber hose fits over the tubing tight or it will just leak.
Have a look and let us know what you find.
Dan.

Canadian "EH"

Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Dec 21, 2005, 3:22 PM

Post #3 of 3 (5116 views)

Re: Blend door actuator	Sign In

Dan's amazing as usual. This problem is almost always a vac leak as he said.

Can't add much but to say if you need to do more than one line - do them one at a time to avoid any chance of mixing them up. If you need and can't find an elbow, try making a loop if there's room out of harm's way. - T

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