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A/C comes out the defroster only? w126 420SEL

4K views 6 replies 5 participants last post by  alexstorm 
#1 ·
I never thought much about it until I saw another post, but when I turn on my AC, it comes only out the dash and the most minuscule amount out of the sides and the center... I saw that most people said it was due to the vacuum pods/acutators needing to be replaced? any thoughts?
 
#2 ·
Center vents only blow during AC operations with the knob set to 65 or lower. Correct me if Im wrong.
Check to see if the vent flap works. Mine was disconnected and fixing that cured my center vents not working.
If that is working fine. Its most likely the vacuum pods behind the dash. Search the topic. Lots of info regarding that issue.
 
#3 ·
Defrost vents are the default for failure. You need to run a full set of diagnostics on your ACC system to see what's going on. There are a lot of reasons why the center vents might not work, the most common being a bad vacuum actuator.

That being said, you could have a dirty thermistor, and bad aspirator pump, etc., etc.

Use the search function for the forum and do some research. You'll find everything you need to know that way - it's a common issue.

Dan
 
#5 ·
I went ahead today and removed the glove box and such, found 3 of the vacuum pods visible.. I'm aware that the center vent one has to be accessed by removing the carpet panel near the radio, if anyone knows how to do that, please do tell. Anyhow, i noticed that the defroster vacuum pod wasn't even moving, i manually pushed the end of the rod and after that initial shove, it opened on it's own the rest of the way, and when i turned AC off, it closed on it's own, but would not turn on unless i shoved it manually. I'm convinced that the defroster one is bad, and that the center vent one is bad also... ordered those two and hopefully that will solve the problem.. checked for any broken rubber on the hoses, though all were in tact.
 

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#4 ·
And "while you're in there" (a common phrase known to us all :wink) checking the pod functions also check for leaks at all the rubber connectors as well as the hard plastic lines. I replaced all the rubber when working on my SE using short pieces of new rubber vacuum hose. If you find a bad (leaking) pod don't be tempted to get rebuild kits as old plastic is brittle and if the tabs break you're stuck with a kit and have to buy new anyway, best bet is just to replace with new, several offerings with online parts houses
 
#6 ·
The carpet is held by a screw down near the lower front part and maybe a plastic "screw" up near the top (CRS moment) the plastic ones only need a 1/4 turn and then pull straight out, you'll have to feel around for it as it's likely buried in the carpet. I take it you have the vent piping out as well as the glove box, that'll give you access to most of the pods, there is another over by the gas pedal behind the carpet. If you don't have a vacuum checker I suggest getting a "MityVac" from the parts store, a visual on the rubber won't tell you much if it's leaking with the rubber being old sometimes they break their seal. The MityVac is handy for checking all the vacuum lines and connectors under the hood where the heat of 25+ years makes em hard and leaky as well
 

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#7 ·
Sounds like you are on the right track. Try listening closely for any air leaks. Sometimes the hose connecting to the back of the vacuum switchover unit have a split end and leak and it's hard to see it, but you can hear it and feel it. I fixed mine with a little dynamat liner, or replace the hose.
 
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