I noticed a problem with my 1996 S420 heater. When I turn the heater on, the rear center vent blows cold air and theairconditioner is on. The front vents are fine and blowing warm air. What would cause this to happen? Please help!

Also, does anyone have an A and B maintenance schedule for this car? I am not sure what are the maintenance intervals and what are supposed to be replaced. I do most of the work myself. Thank you all.

 

Did you just purchase this vehicle, or did you just notice this? In your Owners Manual, it will tell you that it does this. You do have a lever there that you can slide up and down to close or open the vents, but in either case "open or closed" the air is cold. The heat for the rear comes from the floor registers under the seat and can be felt when you select it via the AC/Heater Temperature Control Panel.

I had the same question when I purchased my '97 S420. I had to sit down and read the Owners Manual in order to understand. If you have an Owners Manual, I would suggest reading it to become familiar with it's systems. If not, then you may want to simply order one. You'll find it most helpful.

 

Thanks for the info. I purchasedf the car a year ago and I noticed it ever since. What I do not understand is why the airconditioner is coming on when heat is selected. I actually watched the a/cclutch engaged while the heat is on the front side.

I also read in somewhere in the forum that it does this. I cannot shut off the vent completely. I have to check to make that the flapper is working properly.

 

only the side vent blows warm air. center ones doesn't. it's normal.

 

Sleepwalker,
When you mean normal - normal for the a/c to come on with heater selected? This is what is happening. I get warm air in the front and cold air in the rear center console from the a/c.

 

That's what he's saying, "it's normal."