Lucerne blows(heat) hot on driver side/cold on pass side

Did you ever get an answer? I have the same issue with my '07 Buick Lucerne

I had the same issue this last winter. Had the blend door acutators checked out and all were working. Repair shop said next step was to tear apart the dash and hope we could figure out if one of the blend doors was broken inside the blend box. I decided to leave it alone. Then this summer the opposite was going on. Hot air on the passenger and AC air on driver. I took the car to a different shop and they said that certain years of Buick will do this if the freon is low in the AC system. I laughed at them and thought they were crazy, but figured the AC sytem needed freon anyway since it was low. And guess, what? After they charged up the system, AC air on passenger and driver!! Not sure why, but cannot argue with the results. Now I am hoping that it will be the same in the winter and everyone will be warm.

Hey Bryce! How's it going!? Im still having that problem with my 08 lucerne since last winter...

Hi Rubi726 During the cooling season, charging the freon solved my problem, but now that we are in the heating season I still have the issue you are having. Heat on the driver and colder air on the passenger. Since the acutators are working the only thing I can think of is that there must be something keeping the blend door for the outside air from closing completely. I am curious hear if you figure something out.

I have the same problem, 07 Buick Lucerne CX. Driver side gets hot/cold, passenger side just sits on cold. Don't know about the actuators, will need to look into how to test them.

I have a 2007 Buick Lucerne and I have been experiencing the same issue since last year as well.

i have a 2006 buick lucerne cx 3.8 l only has heat in the rear vents what can i do to fix .

Heat on driver side and cold/much cooler air on the passenger side. Two garages are giving me the same answer. Deep in the dash is a mix box that mixes outside air and inside air. And in this box there are two things that could be causing the problem, trying ot remember but seems like it was a thermostat and another actuator. Either way I have to have someone tear into the dash to the mix box and replace one or both of these items. $800-900 for the labor to get into the dash and then $100-150 for the thermostat or the actuator. So, since they are going that deep and I don't want to do this again I will likely have them replace both of these items for a total of $1200. Ugh.

We had this problem in our 2008 Lucerne 2 years ago. Shop insisted it needed to have the heater core replaced. $900 later it still didn't work right, just didn't get that warm. Took it back in and they said they got heat. Sure they did, when they cranked it up to 90 and took it off "auto". So now we are in a real cold snap and it is not working. Works slightly better on the drivers side but passenger side blows cold air, even when we take it off "auto" and crank it up to almost 80. Also, when it is on auto, regardless of what it is set on, the fan runs continuously without it ever getting up to temp. Don't know what to do now and certainly do not want to put another $900 into it.

I am having same problem, all cold air on the passenger side and warm/cold air on drivers... tech 2 and scanner show all actuators working properly. Is they’re a mix box in the dash that could cause the passenger side to stay cold?

Hi Guru5X79Q, This is how it was explained to me. The driver's side and passenger side have separate "mix/blend boxes". And in these boxes are an actuator allowing outside air to blend with the conditioned air, and this is controlled by a "thermostat" in each mix box. So if the passenger wants 80 degrees, the thermostat would use the actuator to adjust the blend door to achieve this temperature. In my case the drivers side actuator and thermostat worked perfectly, but the passenger side was cold in winter and hot in summer, indicating the blend door was likely open allowing outside air to come in uncontrolled. All tests indicated the actuators were functioning but until the mechanic could tear into the blend box, we would not know if it was the actuator or the thermostat that had failed. And this was something like 9-10 shop hours to tear into the dash and put it back together ($900), and then the thermostat and actuator are about $100-150 each. What we did to try and get by was to manually put the heat in the vent position, blowing air onto our chest/face and close the vents on the passenger side. Also, pointed the right hand drivers side vent toward the passenger. Since then, I have traded the car. Hope this helps

We have come to the same conclusion and are making adjustments to deal with the situation in the winter. I am pretty annoyed that we paid to replace the heater coil when I don't think that was ever the issue. The car stays cool enough in the summer. So we are dealing because other than this it is in great shape and I love the car, I don't want another car payment right now and really, have no interest in putting in another $1100 or so. But thanks for the tip. The other thing we are doing is placing some tape on the small "defroster" vent in the dash. I can't close it and it blows frigid air right on me. Easy to take off if we need it. Am also keeping a lap blanket ... just in case.

Had a similar problem with my 2010 Buick. Heat on the driver side, zero heat on the passenger’s side. From another post it was suggested to flush the heater core. After a few hours tearing apart the dash finding no problem, I flushed the heater core. To my surprise it solve the issue. Now both sides have plenty of heat. I guess it doesn’t take much to plug up the core.

Have the same issue with my 2008- freezing cold on driver's side heat on passenger side and rear vents. For now I'm closing drivers side vents as it is winter. Am not pulling dash! I have had this car 6 months and already struts, shocks, rt cv joint and hun assembly changed. New brakes and rotors, new fuel pump relay, now needs catalytic converter, 4 O2 sensors, ECT module for thermostat and a throttle actuator control module along with a new battery! I am so disappointed with this car!

I had the same problem and I flushed the heater core and it helped. The pass side went from 77 degrees to 125 degrees. big pices of debris came out. The top hose is the inlet and the bottom is the return. Only use about 10 psi of water pressure. Make sure you hook up the the return side with the hose. I'm probably going to do it one more time with a cleaner to break it up some more.

I have a2007 Buick Lucerne and just started having this problem on the passenger side. I called my mechanic and he said there are 3 acutator/blend doors and 2 are fairly easy to get to and one is really hard. I suspect the one that is hard to get to is the one that everyone is referring to as the 9 hour job and the high repair bill. I'm going to stop by after work to see him and have him look at it. It's interesting to note that everyone that is having this problem seems to be on the passenger side and not the drivers side. Seems odd.

My 06 Lucerne does not get hot on passenger side. I removed the glove box and found the actuators. I modulated the temp controls for the passenger side from 60 to 90 and found the actuator does not move its entire length of travel. It looks like it doesn't move fully into heat. Old marks left by the actuator arm showed me how far the actuator needs to go be in heat 100 %. Whether it is improper thermostat signal to the actuator or bad actuator has yet to be determined.

heater core is stopped up flush the core. if it is low in R 134 it will do the opposite

In sure you figured it out by now, but it is 100% your heater core. I just fished mine and it is back to normal.

I have the same problem with my 07 Buick Lucerne with dual temp control. Driver side (luckily) has AC/Heat but the passenger side just let's outside air blow in. It's odd though, when you put it to come out the top of the dash to defrost the windshield it blows out fresh/AC, but when you switch it to dash it's just fresh air. I ripped out the glove box and see 2 actuators on the left but god help me if I can even get a screwdriver over there to get them out. The screws are facing the center of the car and not even stubby screwdriver can get in that area. Even if it could, the screw deeper in side is almost impossible to get to (and that's the closer actuator), the other is deeper in. I have no clue where the 3rd actuator would be that has been mentioned or the thermostat. If I could just put it on heat I'd be fine, the car only needs upper dash in the winter to defrost anyway, other than that AC stays in front of me and I can just close the other vents in summer. Gonna try to get the blower motor out to see if I can see anything else. FYI when you try to take out the glove compartment there are 2 plastic pieces in the hinge you have to remove to get it out all the way. Easy enough with a needle nose. If I find it I'll post back up.

I've been told that the dash has to come out to get to those acuators. Not worth the investment unless you have lots of time and can do it yourself.

I flushed out the heater core and it’s been working fine every since.

To those saying it's the heater core. If that was the problem it wouldn't blow warm/hot on one side and not the other. The specific problem those who are saying one side is warm and the other is cold is an actuator problem. Been there done that.

Is all these issues with dual zone? The reason I ask is we are having the same issue with a non dual zone car. Does not make sense to me unless they use the same box for both.

I had my car at the dealer and they told me the problem of no heat to all passenger side vents is something obstructing the internal ductwork damper flaps. They quoted me $1000 to fix. I did not get it done. My car is dual zone. I think my floor vents dont work either anymore

As I write this solved the problem at least in my situation my wife’s car had a bad water pump and was not circulating the Hot water thoroughly plus the level has gotten a little low replace water pump flushed out system and now heat on passenger side will melt your eyeballs 07 Buick Lucerne. A lot of junk in the flush

Clogged heater core. Because of the dual temps there could be a clog in the area of the heater core that is associated with that side of the car. I've had my heater core back flushed twice and it fixed the issue each time. -06 Lucerne 3.8

Answer: Stop buying American junk...tbh

Same deal...I checked and all actuators are working properly. Then I flushed the heater core and still nothing. The next suggestion some people said was to top up refrigerant (I cant see this working but I will try it). Like one other person said, things on this car start going one item at a time. I have replaced so much stuff on this car, once I get this problem fixed I am going to sell.