JOHNBLAZE

Worst timing ever.. When I press the blue or red button for ac/heat (at top of dash) I get nothing, neither of them light up. However the bottom controls are working fine. I cannot tell if my ac is working though bc its been really cold outside so its going to blow cold air regardless. I cannot get warm out to come out though. Any help is appreciated as mentioned the bottom control unit seems to be working fine, all buttons and knobs are illuminating.

Plutoe

Based upon what you have stated I believe that you have a faulty control module!!

JOHNBLAZE

The unit on the bottom?

dRockSL55

The upper dash buttons don't turn on the ac or heat, all they do is switch between slightly warmer or slightly cooler air than the set temperature from the dash vents only (for comfort during operation) the system will still be working to the temperature you had set below.
if you press the buttons again so neither the blue or red lights are on the dash vents will just use the regulated system temperature.

V12TTenthusiast

I had this same issue too maybe a year ago, does it only blow air thats close to the temp outside? It prob is a bad climate control module and yes thats the unit below the Command System with the AC and knobs itself. Its actually very simple to replace if your somewhat handy.

JOHNBLAZE

So technically my ac should be working fine then correct? I'm not sure about heat though. I cant get any warm air to come out even with the ac off button on and dials set all the way to warm.

dRockSL55

as far as the upper dash buttons are concerned, yes - but that's not to say you don't have issues elsewhere with the system. The purpose of the dash buttons are often misunderstood, probably why MB got rid of them in later model years.

a diagnostic check should be performed on your car. With the dials both fully to the right you should have hot air with a warmed up car. You could have a blend door issue, or a coolant flow issue through heater core (e.g. Air pocket)

JOHNBLAZE

Well it was pretty warm outside yesterday and I would say my ac is working well (thank you lord) but when I switch to heat I get no warm air. Would my ac still be functioning if the control module was faulty? What else could I look at before taking it to the stealership?