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tabasco85331 06-17-2003 11:15 AM

Air conditioner blows out of front window defrosters ?
How can I fix this ? I had my windows tinted the other day and the guy flipped some of my air conditioner controls and since then when I have my air conditioner on normal (arrow pointing down) most of the cool air comes out my defrosters now . My car is an 1989 420 SEL (w126) HELP ! Thanks

Mr. BILL 06-17-2003 11:55 AM

Ah yes, the dreaded A/C out of the defrost. What has happened is your vacuum actuator that controls where the air goes has failed. Those clever Germans made it default to the defrost because in Germany, they use the defroster more than the A/C. Or so I am told that's why.

In any event, you need to replace the actuator. I don't remember if you can get at it by removing the glove box on a 126. On a 124 the whole dash has to come out. It's pretty common for them to fail around 10-12 years.

If your dash has to come out, do yourself a favor and replace them all. I think there's 4 or five that are hard to get to. The actuators are fairly cheap, $25-$35 each. Of course labor ain't. So I'm planning on tackling mine myself.

I did manage a "ghetto" way of keeping the air from blowing out the defroster. I went to Pep Boys and bought some black weather stripping and pressed it into the defrost vent. It doesn't divert the air out to the center vent, but at least your windshield won't fog up. Kind of ironic how it works just the opposite as in Germany.

tabasco85331 06-17-2003 12:57 PM

Thanks . I guess ...

psfred 06-17-2003 11:10 PM

Check to make sure the green plastic vacuum line in the engine compartment is connected -- AC out the defrost is often caused by a lack of vac to run the system.

If you have a hand vac pump, attach it and see the green line holds vac. If not, you have a leak somewhere under the dash, if it does, you have a supply problems, look for broken hoses.

Tinting the windows shouldn't have done anything to the climate control, so I suspect it's coincidence.


ivorysdl 06-18-2003 12:29 AM

Just had a very similar problem with my 87 300SDL (same body as yours). Problem occured after an A/C repair, and the problem was the rubber vacuum connection between the hard plastic line, and the transmission modulator had disintegrated (guess they "bumped" the hard plastic line while replacing the A/C hoses). Discovered several connectors between hard plastic lines and vacuum devises were soft or cracked, so I replaced all of them. Everything works great now, with a cheap and easy fix (transmission also shifts better than it has in years, so some of these may have been leaking for a while).

Fix the vacuum source first, even if it is an actuator, you still have to have a strong source to drive all the actuators.

Good luck

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