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NO heat on my 79 450sl dash control works

837 views 3 replies 4 participants last post by  rowdie 
#1 ·
I'm a newbe, purchased a very nice 107 (red with red interior) 84000 original miles.
But I have no heat, do have hot hose to what looks like a valve on the passenger side fire wall.
Help would be really appraciated.....
.thanks
Chris
 
#3 ·
Mods are going to ask you to fill in your profile as well. That way if someone is in your area they may help. Also lets people know at a glance what year and model car you have without you having to post it on every post.

So, from your description it sounds like you are talking about the heater valve. Should be a vacuum diaphragm on there to control it. Try disconnecting the vacuum hose and connecting a vacuum pump to it. Put a bit of vacuum to it to see if you get the lever off the diaphragm to move and actuate the heater valve control lever. If no, then that is your problem. Not sure on the '79. You may be able to just replace the vacuum on it and be done with it. Otherwise, if like my '77, the replacement was an entire valve in plastic instead of metal like the original.

If the diaphragm works as it should then trace your vacuum line back to the source switch to ensure no issues with the line.

That I believe is the easiest checks on the system. Try that first and then get back to everyone.
 
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