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ironmike, ASE Master Technician GM certified
Category: Buick
Satisfied Customers: 3377
Experience:  ASE Master Tech 30 years GM certified
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My heat only works on the passenger side (one side)

Customer Question

My heat only works on the passenger side. Blows cold air on the drivers. It is a stuck valve?
Submitted: 8 years ago.
Category: Buick
Expert:  ironmike replied 8 years ago.

Thank you for asking your question on JustAnswer. It would help us to know:
-What year is your Car?
-What make and model is your Car?
-How many miles are on your Car?
-What type of engine is in your Car?
-What have you already tried?

Please reply as soon as possible so that we can answer your question.

Customer: replied 7 years ago.

The car is a Buick Park Avenue 1999

120,000 mines

It is a v-6. It is about all I know about it. It is the girlfriends

I have tried messing with the controls going from "auto" to manual. Also, there is a passenger side thermostat adjustment that I have played with to see if I can pinpoint on the problem

In the summer, the air conditioning didn't work that well. Don't know if that adds to the heat on on passenger side issue.

Expert:  ironmike replied 7 years ago.

If this has dual zone climate control the system will have two actuators that control blend air doors. If one is not working or stuck closed or open it will effect temp settings. I would move the temp settings and check to see if the actuators are moving.

This is how alldata describes the system

The dual zone (CJ2) system utilizes 1 actuator for the passenger side and 1 for the driver's side.

The single zone (C68) A/C system utilizes 1 air mix valve actuator. This actuator adjusts the temperature for the entire vehicle.

The air mix valve actuators control the outlet air temperature commanded by the heater and A/C programmer.

A reversible DC motor in the actuators operates the air mix valves. The valves determine how much air passes through the heater core for each side of the vehicle. Refer to the following list:

  • When maximum cooling is required, the motors move the valves and block the air flow through the heater core. No heating of the system air occurs.
  • When maximum heating is required, the motors move the valves and force all of the air to flow through the heater core. Maximum heating of the system air occurs.

The driver air mix valve actuator is contained in the heater and A/C programmer. This actuator controls the temperature of the discharge air on the driver side by operating the driver air mix valve. The valve directs air through or around the heater core.

The passenger air mix valve actuator is mounted on the heater and A/C module assembly.

When not operating in dual zone mode, the 2 actuators will operate the mix valves in unison.

The air mix valve actuators contain feedback potentiometers. The feedback potentiometers inform the heater and A/C programmer of air mix valve positions.

Good luck.

Customer: replied 7 years ago.

This is a dual climate control system. The passenger has a "lever" on the far right, to adjust their settings. I don't know what the heater and A/C programmer is so I wouldn't know what I am looking for. Can you help on that? Maybe a diagram?

With this all said, it could be the programmer or an air mix valve.

Expert:  ironmike replied 7 years ago.

Alldata is not clear but on both they say to remove the instrument panel. They give 4.5 on time so i think they dash board has to be removed. Sometimes I will remove the radio or a/c control assembly to see into the dash to find components. Once in a while you can cheat and sneak something out without removing the dash. here are the pictures they give for the drivers side


  1. Remove the aspirator muffler.
  2. Remove the electrical connector from the driver air mix actuator.
  3. Remove the driver air mix actuator retaining screws (1).

Good luck

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