[W126 Coupe] Heater stuck in "on" position

[Robert Karl Stonjek]

> Hi Everyone,
> Heater pumps hot air through the interior vents. Heater blower 
> non-functioning.  None of the climate control buttons work. What would be 
> the order of things to check out? How to disconnect the heater, at least 
> temprarily?. Weather's getting hot in So Cal.
> Thanks for advice.
> Waldemar 1989 560 SEC
> 

It may be a good time to take a motoring holiday to South America.

Failing that, try to get hold of a second hand climate control unit and change it over.  If none of the climate control buttons work then you have issues there unless the blower, mono valve and airconditioner control have all gone on strike together.

With such a comprehensive failure you may be lucky - it may be a loose connection to the climate control.  It's a good idea to disconnect the battery while your poking around behind the dashboard.

To get at the climate control you have to remove the centre console dashboard.  Start at the horizontal cover that has the window switches.  Lift it up where it buts onto the horizontal plastic bit forward of the gear selector.

Remove that plastic bit.  Then pull out the ash tray and remove its innards.  You should be able to see the two screws that hold the sliding rails in place.  Remove them and the ash tray and rails will slide out but there are two electrical connections at the rear - one for the lighter and one for a light.  Disconnect them as you work the ash tray out.

Next remove the hifi - these are all different (usually the original has been replaced by now) but generally its a case of removing the front cover and loosening screws, then it should slide out - you may be able to rest it near the gear stick without disconnecting cables.

You should now be able to see the two screws that hold the dashboard in which the climate control is found.  Remove them and pull the dashboard down. It should pop out at the top.  It can now be turned around to expose the climate control unit.  You will have to remove the large plugs at the back (check them to see if they are loose - never know your luck :).  There is one of these large plugs on either side, left and right. You may have to remove the plug from one or more of the switches to get the dashboard out far enough to remove the screws holding the climate control in place (There's one screw on the top, one on each end, two below).

The unit is now liberated.  Dismantling the unit is straight forward if you know how, but that's another story.  I've got two spares, but I haven't finished reconditioning them - I intend to use the best one for myself but they should all be the same by the time I've finished.  I replace all the transistors and capacitors, clean the switches, replace the globes etc.  I paid $129.26US for one of the units, can't recall what I paid for the other (had feelers out for a unit and then got two hits at the same time! one was from the Canadian EBay).

The only thing wrong with the unit I currently have in the car is that it tends to switch directly from heating to air conditioning.  But when I first got the car the unit didn't work at all - I partially reconditioned one unit and installed it and will probably install the original unit when it is fully restored (when I get around to it).

Robert
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