87 420 no center vents on all positions
 

just a quick ? on analysis.

my 87 420sel does not send air thru the center vents on any setting of the climate control switches.

would this mean more than one or all the actuators could be bad or just the main vaccuum line to the climate control?

and 1 last ?. i've read several post describe a green vacuum line thru the dash causing problems....but the only vac line i can see is the one from the engine manifold. i've looked 3-4 times and i can not see a green vac line. i do see some vac line on the right side back behind the battery but they are not green. what am i doing wrong?

tks
craig

No air from the center vents on max cool (thumbwheel on min, button with black up arrow and white down arrow selected) could mean no source vacuum or a problem with the diverter actuator. I think you'd get some air from the center vents if there was no source vacuum because the center actuator would be at rest with the center vent flap open. That would allow some backflow to the center vents. Do the defrost vents close when it's on max cool? If so, you have source vacuum.

The center actuator of my SD is bad so I get heat through the center vent. Take that, MB :) The compressor is long gone so there's no AC.

I don't know about any green line. Sounds like something you'll find in Boston.

Sixto
95 S420
91 300SE
87 300SDL
83 300SD

center vent air
 

tks for your response.

i may have over stated no air. there is only enough to feel it. there is no projection of air only the slightest faint of air. 3 inch from the vent you wouldn't know it had any air.

there is one actuator that appears to work. i removed the glove box so i can see the one on the right. with the car on when you actuate it, it does move but no center air. i've held it in place and no center air.

this is all i can say because that is it as far as my probing has gone.

tks much
craig

Through the glove box opening you'll see tandem actuators for the recirc flaps. Stick your hand in to the left and up and you'll feel the defrost actuator. You have to remove the ACC control panel to get to the center vent and footwell actuators. I've never seen the diverter actuator but I believe it's inboard of the accelerator pedal.

Sixto
95 S420
91 300SE
87 300SDL
83 300SD

I don't believe the AC line in the W126 is green for some reason. Grey and red?

Whatever.

It will have a check valve, so you can just hook the ol mitivac to all the lines going to the passenger compartment and draw a vac. One will be the vac "economy" gauge on the dash if you have one.

If you get a system that moves the flaps as you push the buttons but leaks down, you have some bad diaphrams or swtichover valves (they don't usually fail, but it's not impossible). If it works fine with the MitiVac, you have a bad hose going to the manifold.

Peter