Heater blowing cold air only on drivers side

Tiny
DUMNDAC
  • MEMBER
  • 1998 BUICK CENTURY
  • 3.1L
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 89,000 MILES
- With temperature set to max on HVAC head, middle-level vents blew cold air on drivers side (always) passenger side responded correctly to temperature setting (unit was not in dual mode).

- Reset by disconnecting battery for one hour.

- After re-connection, problem was solved.

- However, upon turning off/on, problem was back immediately.

- Noticed that whenever HVAC was turned on, the A/C clutch became engaged (even though temperature set high and it was cold out).

- Disconnected fuse for A/C clutch, driver side stayed cool (not cold presumably outside air). Temperature setting still had not effect. Passenger side still hot.

- After ten minutes, tried lowering temp from max to min slowly, then raising to max. All of a sudden, hot air out of all vents.

- Is there a driver side thermostat separate from the passenger side? Faulty thermostat? If it were just a faulty driver-side flap actuator that would not explain why the A/C clutch is engaged when it should not be.

Thoughts/suggestions appreciated.
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Monday, November 12th, 2018 AT 10:46 AM

3 Replies

Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
Good afternoon.

Since you have auto climate control, the AC compressor comes on with all functions. It never turns off. That is normal.

As far as the blend door actuator, if you reset it and it went back to not working, the actuator is the issue. When it is replaced then you can calibrate it for the final step.

Procedure

Remove or Disconnect

1. Battery ground (negative) cable.
2. Instrument panel carrier.
3. Electrical connector to temperature valve electric actuator.
4. Mounting screws to temperature valve electric actuator.
5. Temperature valve electric actuator.

Install or Connect

1. Temperature valve electric actuator.
2. Mounting screws to temperature valve electric actuator.

Tighten
Screws to 1.5 N.M (13 lb. In.).

3. Electrical connector to temperature valve electric actuator.
4. Instrument panel carrier.
5. Battery ground (negative) cable.
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Monday, November 12th, 2018 AT 11:29 AM
Tiny
DUMNDAC
  • MEMBER
  • 2 POSTS
Thank you for your reply, very helpful.

Am I correct in saying that the the blend door is responsible for mixing hot and cold air to achieve the correct temperature? If so, are there typically two blend doors actuators if the car has dual-side climate controls (driver and passenger side)? I have been searching parts lists and have not found a definitive answer. I know there are two types of actuators for auto vs. Manual climate control, but I get conflicting answers on whether there are two blend door actuators in the system.
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Tuesday, November 13th, 2018 AT 9:25 AM
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
The actuators are the same.

You have one for each side.

The blend door actuator moves a door that directs either cold air or hot air based on the command.

Roy
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Tuesday, November 13th, 2018 AT 9:29 AM

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