Temp control works on passenger side but not on drivers side

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Cooter75
Posts: 1
Joined: Tue Oct 18, 2016 7:30 pm

99 Buick Regal problems

Unread post by Cooter75 » Tue Oct 18, 2016 7:37 pm

Having problems with my lights, and I need some help. When I turn the lights on the reverse lights stay on the whole time. They stay on when it's in park and while driving. When the automatic lights turn off they stay off. I have brake lights and my blinkers work, however my plate lights are out and the other 4 tail lights. I checked the fuse for tail lights and it was fine. I am stumped and need some help!!

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carriedi
Posts: 2445
Joined: Wed Apr 10, 2013 12:42 pm

Re: 99 Buick Regal problems

Unread post by carriedi » Wed Oct 19, 2016 10:58 pm

if there is no trailer hook up on your car I would look at the wiring for your reverse lights and for the parking lights for the rear of the vehicle.

dumndac
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Joined: Mon Nov 12, 2018 11:57 am

Temp control works on passenger side but not on drivers side

Unread post by dumndac » Mon Nov 12, 2018 12:00 pm

1998 Buick Century Limited: IIt's winter and I would like hot air to come out of both the driver side and passenger side middle-level vents. The problem is that cold air comes out of driver side and hot air comes out of passenger side. Here are some clues:

- No amount of fiddling with the HVAC buttons in Auto or Manual mode seemed to fix the problem. Most of my tests were in manual mode because Auto seemed to behave the same. Also DUAL mode was OFF during these tests.
- Changing the temperature changed the temperature of the air on the passenger side but the driver side remained cold and unchanged. When temperature was set lower, both side would push cold air. At max high-temp, still cold air on driver side and then passenger side back to hot.
- I performed a 'reset' by disconnecting the battery for an hour
- Upon re-connection, the first thing I noticed was that the yellow Auto button light on the HVAC head was working. This wasn't working before.
- The second thing I noticed that the fan wouldn't come on. By fiddling with the buttons for 5 minutes, the fan came on.
- However, as soon as the fan came on, lo and behold, I got hot air coming from both driver and passenger side vents!
- To verify that this was not just a one-time thing, I turned the car off and then on.
- Immediately the original problem returned: cold air on driver side, hot air passenger side.
- The fan was also hard to start but I noticed that if I removed and put back the blower fuse, the fan would almost always start working again. (The fan is more of a red-herring....the temperature problem is the main thing I need to solve.)
- Btw, somewhere along the way the Auto button yellow light stopped working again.
- I noticed something weird: When HVAC was off, whenever a pushed a button to turn the unit on, I could hear the engine strain. It acted like, no matter what, the A/C compressor was turning on (even though the temperature was set to max-high and it was cold outside).
- Sure enough, I noticed the A/C clutch would engage whenever a button was pushed on the HVAC. I removed the fuse for the A/C clutch.
- From this point on, the compressor did not engage, however the driver side vent continued to blow "cool" (but not cold) air. Passenger side still hot.
- During testing, somehow, magically, after the HVAC was on for about 10 minutes, the driver side started blowing hot air.
- I turned car off and then on, and the problem returned immediately. The driver side blowing cold air, passenger side hot
- This morning on way to work, I waited to see if the driver side would magically start blowing hot. It didn't.
- Then, after about 10 minutes, just on a hunch, I lowered the temperature as low as it could go, and then raised it again to max
- Voila, both sides start blowing hot air.
- My question: Is there a driver side thermostat separate from the passenger side? If so, it seems like the driver side thermostat always thinks that the temperature is "too hot" and thus turns the A/C on and then channels the A/C cold air into the driver side vents because it thinks it should be cooling the driver off even though it should be heating things up. Also, apparently, even when the A/C clutch is disconnected, it puts some flap in position to channel air from the A/C to the driver side vent, rather than channel air from the heater.
- At first thought, one might think that the driver side actuator that controls a flap may be at fault. However, if this were true, why would the HVAC be initiating the A/C clutch when it shouldn't? If it was just a flap actuator problem and the thermostat was working properly, the A/C clutch would not be engaged, but the driver side would blow "cool" (outside) air.

Thoughts and suggestions much appreciated.

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carriedi
Posts: 2445
Joined: Wed Apr 10, 2013 12:42 pm

Re: Temp control works on passenger side but not on drivers

Unread post by carriedi » Mon Nov 12, 2018 9:10 pm

not sure because of the year of the vehicle but most cars have a computer that runs the hvac. the computer can be scanned for codes and can have the data stream for the door actuators to see if they are moving correctly. You can watch the controls say to move and see what the door move to or if they are not moving. you can watch both blend doors and see if they both have the same range of movement. Without using a scanner it would be hard to see what the controls and what the actuators are doing. The hvac codes are not emission related so they don't turn on the check engine light on. They just store codes in the hvac module.

a common problem with the actuators is that the worm gear and the wheel teeth get worn and then when the wheel gets to one end of movement the worm gear will spin and the gear won't move anymore. Sometimes it will catch and sometimes it won't. As it gets worse the more it won't work right.

most code readers won't do the HVAC module. They are mostly for emissions. Some add abs and airbags. But body, hvac, security, etc. will need an better scanner to read them and watch their data streams.

Iketomtom

2016 Buick regal hvac system not working

Unread post by Iketomtom » Fri May 31, 2019 7:12 pm

A few days ago my hvac controls went completely black and haven't came back on. I'm looking for advice on where to start so I can fix problem

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carriedi
Posts: 2445
Joined: Wed Apr 10, 2013 12:42 pm

Re: 2016 Buick regal hvac system not working

Unread post by carriedi » Sat Jun 01, 2019 6:38 am

the first thing I would do is look for a blown fuse. The HVAC module is powered up by fuse #17 in the instrument panel fuse block in the lower left side of the dash. Should be a 10 amp fuse.

here is a picture of where the fuse #17 should be. By the book anyways. Sometimes the book is not correct.

If the fuse is good and has power with the ignition key in the run position, then you have to remove the hvac controls and check the powers and grounds. If all the powers and grounds are good you will probably have to replace the hvac control module.

Have the vehicle scanned. They should be able to scan the hvac module. I'm thinking that there won't be any communication with that module because if nothing lights up or turns on there probably won't be any computer communication. Scanning for all codes may turn up a clue before the module went completely out. It's an easy check.
Attachments
regal hvac fuse.jpg

Tommy

Re: 2016 Buick regal hvac system not working

Unread post by Tommy » Tue Apr 07, 2020 12:34 am

Iketomtom wrote:
Fri May 31, 2019 7:12 pm
A few days ago my hvac controls went completely black and haven't came back on. I'm looking for advice on where to start so I can fix problem
If there are no blown fuses, try tapping on the front face of the controls. If it flickers, then the control head needs to be replaced.

oylmpicregal

Re: Temp control works on passenger side but not on drivers side

Unread post by oylmpicregal » Sat Nov 13, 2021 1:06 am

Hvac actuator can be accessed by opening the glovebox and it can be drop down and behind the glove box you will find the actuator. go to Youtube and type in: " replacement for Hvac actuator on 95 Buick Le Sabre:

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