Heat only works on the passenger's side of the car?

2003 BUICK REGAL

130,000 MILES • 3.5L • 6 CYL • FWD • AUTOMATIC

DP12345

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heat only works on the passengers side of the car. the heater has a split heat selector for the driver and passenger vents. all cycles work from vent to defrost. heater door passenger side works properly. unable to see if the door on the driver side of the vehicle is working but the vacuum is working when switching trough the cycles. the A/C does work on both sides.

Jan 4, 2014 at 9:46 AM

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SQM

AUTOMOTIVE REPAIR CONTRIBUTOR
6,383 POSTS

Hello,

It sounds like the issue is with the blend door actuator.
The blend door actuator is what controls the air door for hot and cold air mix.
Many times, when the actuator fails, it will fail either in the hot or the cold side. Which will lead to no heat or no AC issues.
This vehicle has 2 blend door actuators, one for the drive and other for the passenger side.
The drive side actuator is located on the left side of the HVAC box which is located behind the instrument panel.

Here is a helpful guide:

https://www.2carpros.com/articles/replace-blend-door-motor

I have attached diagrams for your reference.

Please let me know if you have any questions.
Thank you.

Images (Click to enlarge)

Jan 10, 2022 at 1:23 PM