07 lucerne cx manual hvac no heat

[LucerneLover]

I need your help guys. My 07 lucerne cx isnt putting out any heat. I mean it does eventually when you get going but only on the far left vent next to the door. Ive had the thermost and water pump replaced recently. Also back flushed the heater core to no avail. Perhaps theres air in the system that needs to be bled? That or the worst scenario and an actuator is out. But i got underneath both sides of my dash and all actuators and working as they should. Some advice or experience with this problem would be very helpful, thanks

 

[2007LucerneCXL]

Air in the system can always be a problem. Does the temperature gauge read properly? Here's a diagram on the system showing all the components which may help on identification of a non functioning acuator. Also, not sure on the CX if it has a passenger side on the controls but that may be something to look at.

 

[LucerneLover]

It's a manual system, not climate controlled.

 

[2007LucerneCXL]

My error it was in your post title, you could just let the car get up to operating temperature and check the heat on the two heater hoses which would let you know if it's working or its inside issue.

 

[LucerneLover]

Last time i checked it felt like both hoses were hot maybe one was slightly cooler

 

[2007LucerneCXL]

It's sort of pointing to a actuator, unfortunately I'm not sure if they would be visible from under the dash but you may check what you can see against the diagram.

 

[LucerneLover]

So upon further examination during my cooling system burp process theres were several air bubbles that emerged and also the top hose going to the heater core is to hot to touch but the bottom hose is warm but i can grab it

 

[2007LucerneCXL]

There's a few online listing on how to burp a system, several times may be required to get it cleared out no rule on a single time. Hopefully that may fix the problem.

 

[LucerneLover]

Is there a way to open or close the actuators by hand? And which ones do i need to do?

 

[LucerneLover]

So I've done this before. I flushed my cooling system and the heater works amazing now so i know now it's not an actuator. But after a while it'll get cool again. What would cause this?

 

[2007LucerneCXL]

It could be that there is still some sludge in the cooling system and may require multiple flushing.

The other items that could be, again air in the system or possibly a thermostat that is sticking open check your temperature gauge even if a new thermostat has been installed it could be defective.

On the coolant level check the radiator cap when cool don't be dependent on the overflow tank level especially if it's been changed.

 

[LucerneLover]

Yeah my mechanic said its gonna need multiple flushes probably. The dealer just let it sit there with water so theres alot of rust and buildup that needs to be removed. So im thinking of putting cooling system cleaner in it and driving it around until middle of next month and flushing again

 

[0123BRAD]

Hello,

I had to do two things
1. verify the heat/cool door and electric actuator on the HVAC unit worked
2. If the door works, the heater core must be flushed.

1.
How I checked the 'heat/cool door' Thanks to all on this forum for your help(s).

I recently had a 'no heat on the passenger side' condition on my 2008 Lucerne CXL 3.8. I removed the under dash passenger panel, observed the heat/cool door motor by going on/off full cool and heat for the passenger side, 60 and 90 degrees if I remember right. The motor was working a-ok but I needed to know if the door inside the assembly was actually moving and not broke at the shaft. I very gently popped off the actuary lever, moved the door by hand, I could hear and feel the door was intact and moving/sealing. What a relief!

2.
Flush, dare I say wash as well?

One hose on the larger heater core inlet to a bucket as a drain, one hose 'connector' to the smaller heater core hose.
The smaller heater core connector needs to allow a very solid seal with the end of a oil suction gun from Harbor Freight Tools and still allow the gun to be removed to suck up another bunch of liquid to be pushed through the core, link below.
I used the gun to suck up a large quantity of hot water, push the hot water one way through the small or outlet hose at first gently, then a few times, forcefully.

Then I used full strength CLR, added what I thought was the right amount to fill the heater core. Let it sit no longer than 5 minutes. The oil suction gun allowed me push and pull liquid back and forth through the core to 'wash' it. Then I reflushed/rewashed the core with water a few more times.

Put the coolant I drained back into the system, it looked good as the radiator was just replaced before I bought the car.

I now have heat on both sides!! Yea!!


What I used.
2 buckets, one for drain water, one for feed water.
Lots of water hot and cold
CLR, 28 oz
Suction Gun from Harbor Freight Tools Suction Gun

Various hoses, 2 plastic hose connectors one sized for the large heater hose, the other for the smaller heater hose, hose clamps..

Good Luck!

 

[Tomislav]

Hello,

I had to do two things
1. verify the heat/cool door and electric actuator on the HVAC unit worked
2. If the door works, the heater core must be flushed.

1.
How I checked the 'heat/cool door' Thanks to all on this forum for your help(s).

I recently had a 'no heat on the passenger side' condition on my 2008 Lucerne CXL 3.8. I removed the under dash passenger panel, observed the heat/cool door motor by going on/off full cool and heat for the passenger side, 60 and 90 degrees if I remember right. The motor was working a-ok but I needed to know if the door inside the assembly was actually moving and not broke at the shaft. I very gently popped off the actuary lever, moved the door by hand, I could hear and feel the door was intact and moving/sealing. What a relief!

2.
Flush, dare I say wash as well?

One hose on the larger heater core inlet to a bucket as a drain, one hose 'connector' to the smaller heater core hose.
The smaller heater core connector needs to allow a very solid seal with the end of a oil suction gun from Harbor Freight Tools and still allow the gun to be removed to suck up another bunch of liquid to be pushed through the core, link below.
I used the gun to suck up a large quantity of hot water, push the hot water one way through the small or outlet hose at first gently, then a few times, forcefully.

Then I used full strength CLR, added what I thought was the right amount to fill the heater core. Let it sit no longer than 5 minutes. The oil suction gun allowed me push and pull liquid back and forth through the core to 'wash' it. Then I reflushed/rewashed the core with water a few more times.

Put the coolant I drained back into the system, it looked good as the radiator was just replaced before I bought the car.

I now have heat on both sides!! Yea!!


What I used.
2 buckets, one for drain water, one for feed water.
Lots of water hot and cold
CLR, 28 oz
Suction Gun from Harbor Freight Tools Suction Gun

Various hoses, 2 plastic hose connectors one sized for the large heater hose, the other for the smaller heater hose, hose clamps..

Good Luck!

Did anyone ever fully successfully fix the problem of no heat on passenger side?
It seams like every single Lucerne has that problem...

 

[2007LucerneCXL]

As with most newer vehicles, check other GM forums and models, it's a actuator that has gone bad. From that point on as with this post it could be the heater core, thermostat, air in the cooling system or possibly the HVAC control unit, but these items will all be the same problem on any vehicle. Why are you asking?