Spazzing blend door actuator

[Matthew Jeschke]

My blend door actuator doesn't behave correctly. I have replaced twice. My truck is a 2001 Tahoe.

Original: broken gear so discarded.

Replacement from salvage yard: I don't know what year I pulled from but was a 2nd gen Tahoe era truck. I put in the truck and head unit / controls will operate it but not as expected:

- Full cold, constantly spazes out but hold door to evap side.
- One click to hot - moves door half way between evap and heater core.
- Full hot - moves door all way to full heater core.

Third Replacement - purchased but doesn't seem to work at all. Pins seem to be different despite RockAuto spec'ed it for a 2001.

Head unit - I replaced the head unit some time ago. However, part number on back of head unit was exact same part number.

Video of issue linked below:

blendDoorActuatorMalfunction.mp4

drive.google.com

 

[RED TAHOE LS]

99 % of the time, with loss of VACUUM, default defrost to the windshield is common. You have a pinched hose under the dash OR as well as under the hood.

 

[swathdiver]

My blend door actuator doesn't behave correctly. I have replaced twice. My truck is a 2001 Tahoe.

Original: broken gear so discarded.

Replacement from salvage yard: I don't know what year I pulled from but was a 2nd gen Tahoe era truck. I put in the truck and head unit / controls will operate it but not as expected:

- Full cold, constantly spazes out but hold door to evap side.
- One click to hot - moves door half way between evap and heater core.
- Full hot - moves door all way to full heater core.

Third Replacement - purchased but doesn't seem to work at all. Pins seem to be different despite RockAuto spec'ed it for a 2001.

Head unit - I replaced the head unit some time ago. However, part number on back of head unit was exact same part number.

Video of issue linked below:

blendDoorActuatorMalfunction.mp4

drive.google.com

Matt, you ought to get the internal codes to see exactly what is wrong. Use GM OE/ACDelco Professional for best results.

 

[RED TAHOE LS]

This problem was common long before ECU and computerized electronics were ever thought of.

 

[Fless]

99 % of the time, with loss of VACUUM, default defrost to the windshield is common. You have a pinched hose under the dash OR as well as under the hood.

2001 blend doors are electronic, not vacuum.

I remember driving an old '55-some Chevy and stepping on the gas with the wipers going. The instant loss of engine vacuum would stop the wipers in their tracks.

 

[treehan77]

Are you doing the relearn procedure, or just installing new blend doors and carrying in without doing the procedure?

 

[RED TAHOE LS]

2001 blend doors are electronic, not vacuum.

I remember driving an old '55-some Chevy and stepping on the gas with the wipers going. The instant loss of engine vacuum would stop the wipers in their tracks.

Thanks for the memories, @ 226k, i've had no need to pull my dash apart because it's never given any problems. I am aware the control panel is solenoid operational by means of assistance to vacuum modules, jmho..........good luck.

 

[swathdiver]

This problem was common long before ECU and computerized electronics were ever thought of.

800s and 900s and beyond are all electronic now. No more vacuum. In the old days, when the air went to the floor it was usually a hose fell off or was rotten. When the heat quit working, the vacuum hose came off the heater valve or the valve got stock, easy to diagnose and fix and very reliable. Now we have to have a computer to diagnose all these electronic pieces.