Mercedes-Benz Forum banner

HVAC issues

748 views 1 reply 1 participant last post by  newbnz 
#1 ·
Hi everyone,

My '88 2.3 has recently started giving me a nightmare in the HVAC department. It's blowing scalding hot air out the side vents and defrost, and normal or cold (when the a/c is on) air out the center. The vents don't change when I push the buttons...

I have checked everything...and i mean EVERYTHING. Here's where I'm at.

when I put a mitivac on the green/red vac line from the check valve under the hood I can pull 22" and it will hold all day with the defrost button selected. If I change the selection the vac looses vacuum and I can't pull it won't hold anything.

When I pull the lines off of the gizmos behind the dash that I can reach (3 of them) all have vacuum with the engine running, and I can see levers moving and such when I make selections on the controls.

The water valve has vacuum, but doesn't seem to change (open or close) when i change the temperature knob. There is no difference in the amount of heat coming from the vents if I actuate the valve manualy, which tells me I need a new water valve..no problem.

So why won't my vents change? Could the HVAC pushbutton controller itself be bad?
 
See less See more
#2 ·
I did just notice, while testing the switchover valve again...the vacuum at the switchover is very low...and the switchover gets VERY HOT to the touch...it burned my fingers quite badly...that can't be normal...
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top