[giddygoat]

I have a 06 Lecerne with the 3.8 v6. The heat on the passenger sided blows cold, drivers side and back seat are hot. I tried resetting the system with no luck, the controls work and servos move the shafts for the doors. Would it be the door is broke inside or could something else be going on that I am missing? Flow thru the heater core appears good, full of antifreeze no rust or corrosion. Anyone else seen this issue?

[salem1912]

I presume it has L-R zone heating?

[giddygoat]

No it does not...

[salem1912]

If possible switch the heater hoses to get a reverse flow and see if that helps. I had a heater core that was somewhat clogged and depending what side of the duct work was over top of the good half got the heat. Most cores dump hot water into the tank if the "field"part is clogged then it will just go back out the other hose and never cross the core part. Is the left side hot or just warm?

[giddygoat]

Left side is hot (drivers side) I did put in some stop leak awhile ago as well as changing out the battery (can screw up the heater calibrations). Had a small leak that I could smell but never find, turned out to be the water pump. It could be that it plugged up the heater core, not something that is easy to switch out. Thanks for the reverse flow idea, will give that a try and see if makes a difference.

[6t7gto]

When I was twisting wrenches and customers complained of no heat, I would blow the heater core out with air.
Low pressure. You will be surprised of the crap that will come out.
But if you are getting heat on the driver's side I doubt it has anything to do with the heater core.