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Old 12-31-2004, 03:48 PM
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Join Date: Dec 2004
Posts: 1
W126 (1986) Climate Control Problems

My '86 560 SEL has problems directing heat to the floor and to the dash outlets. The CCU buttons seems to be failing to control vacuum to the doors. I sit reasonable to start by replacing the pushbutton unit? Heat and A/C via the dial are normal. Tempatures are normal. Fan control and defrost are normal. Thanks in advance and Happy New Year. Peace everyone! Mike

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Old 12-31-2004, 04:19 PM
engatwork's Avatar
Join Date: May 2000
Location: Soperton, Ga. USA
Posts: 12,429
You can take your pushbutton unit out and send it to have it rebuilt or you can try it yourself. Do a search on this site for any items you may have issues with.

Oh yea - welcome aboard.
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Old 12-31-2004, 04:57 PM
Join Date: Aug 2000
Location: Holland, MI
Posts: 1,316
Quick check/review of operation:

Normal operation is Heating only from the floor outlets, Cooling air only from the center outlets. Side dash outlets heat and cool.

Have you tested for floor outlet vacuum in Heating, #3 valve of the seven valves located to the right of the console?

Here are a couple of related threads, they might help

Heat/no heat issues

w126 heater vent intermitent by feet

Re-soldering the ACCU has helped, once other causes have been eliminated.

Best Regards,
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Old 12-31-2004, 06:18 PM
meltedpanda's Avatar
Certified Benzaholic
Join Date: Mar 2003
Location: Central Ky
Posts: 6,139
sounds like a diaphram/vacuum issue to me and not pushbutton unit. On my 84 I had to relplace the actuators so my vents would open and close. The one to the floor is still not functioning and I choose to open these manually in the winter and close them in the summer
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Old 12-31-2004, 10:15 PM
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Join Date: Oct 2001
Location: Dallas, Texas
Posts: 19
Climate Control

I had a very similar experience on my 1986 420 SEL....began to remove the actuators and see if any diaphragms were bad.....before that I removed the CCU...and after a few minutes found the three solder joints on the printed circuit board that hold the temperature adjustment pot were all loose!!!!

Resoldered, put back into the car - NO MORE PROBLEM!!!!

Still working--and the air comes from the correct vents and temperature holds steady!!!

Good Luck!!
Mark Pavelka

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