406: Clicking Air Circulation Motor

Just got this problem on 98 406 SL where motor clicks (presumably) because
the limit switch is not working.

I have disconnected the motor - which requires a contortionist to reach the
comnnector - so I can have the air on external (I never use the recirc mode
anyway).

Q: Any sort of repair looks difficult for access reasons. How difficult is
it, and what roughly are the parts costs?

Chris K

 

Don't know if I can answer your question--but I will add one of my own--is
the clicking coming from beneath the glovebox? I have a 1998 406 SRDT, and
ever since the dealer changed the pollen filter this constant clicking
began. I had them look at it and they reckoned it had nothing to do with
changing the filter; but they didn't fix the clicking either. Is this the
same problem?
Bryn Parry
Tasmania

 

Hi Bryn,

This is quite likely to be the result of changing the pollen filter as when the
filter is removed, crap can drop down into the heater airways. The secret is to
hoover up all the dirt on the outside of the old filter first before taking it
out. One cause of the dreaded clicking flap motor syndrome is a stuck flap,
jammed by dirt. I've not had this but instead had problems with the hot/cold
mixing flap on the right hand side of the heater.This turned out to be a problem
with the electronics which for me as an electronic engineer was much easier to
fix. I did take off the drive motor however. The re-circulate motor is on the
left hands side as you sit in the car an is screwed onto the side cheek of the
heater box. Once removed you can work the flaps by hand and hopefully dislodge
what ever is jamming the flap. Make sure you re-engage the motor drive and
flapat the right place eg moter set to fully open and the flap fully open.
Otherwise you will have to take is all out again. (don't ask how I know this!!)
Test it all before refitting all the trim.
This is an awkward job = lots of time = expense if you ask your garage to do it.
Definitely a DIY job I reckon.

Good luck

 

No, the flap is not jammed, works OK in response to the switch but when it
gets into the fully open position, the motor does not stop. The clicking
noise sounds like plastic gearwhhels skipping. I can't really see what the
mechanism looks like without dismantling around the fascia whch I am not
going to do in the middle of Winter. Looks like a time consuming job - does
anyone know what needs replacing once you get there? The Haynes book does
not mention it.

One for lighter (and warmer) times I think.

Chris K

 

OK understood. I don't know how the motor is controlled at the ends of the
travel. On the temp control motor flap, the electronic driver limits the current
when the motor stalls but the freshair/recirculate flap only has to be open or
shut and so possibly uses a limit switch, possibly inside the drive gearbox. I'd
take it off the heater flap box and play with it indoors in the warm to see what
happens and how it works.
In the meantime turn up the radio!!

Bob

 

I assssumed it was limit switches but it could be sensing the motor stall -
in which case it is probably stripped gear teeth or something like that
causing the motor never to stall.

Easier to disconnect it, I don't think I could stand the graunching noise
knowing that it was running continuously making repair ever more unlikely.
Driving around for a few days on recirc has been very bad for misting up.
Never use the recirc position anyway.

Chris K

 

not sure on price of part but about half hour to change(done quite a few b4
migrating to fords)