406 heater problem - can you help

RobW · Post by **RobW** » 23 Mar 2005, 11:16

I have a 1997 (R) 1.9 GLX TD. The heater only blows hot air out when the temp is set at 30Deg, but blows cold out between 14 and 29. Theres no fault in the fan, as that works full range in both manual and auto, and no fault in the A/C.
I had a radiator leak 2 weeks ago and put in some radweld and topped up the coolant.
I've read about other similar problems and have since tried bleeding the system using the empty coke bottle method but no joy. I haven't flushed the system either yet.
Are there only 2 bleed points ?
Whats the best way to flush and what do you use ?
Is it anything to do with the air mover flap on the fan ?
Is there anything else I should be looking at ?

tonespeed1999 · Post by **tonespeed1999** » 24 Mar 2005, 01:18

sounds like the main climate control curcuit board is faulty.
the 306 used to suffer with the same problem,cold air on one setting and hot air on the next.

RobW · Post by **RobW** » 24 Mar 2005, 02:44

Thanks for your reply. Is the board located near to the blower and can you do it yourself ?
I haven't had chance to do anything yet, but something I found today was when the fan is in manual on full, and I ramp the temp from min to max, there is a drop in the tone of the fan a couple of seconds ater it reaches the max, then a single click somewhere around the glovebox. When the fan is on full at 29 deg it sounds normal then when I increase it to 30 the same happens.

RobW · Post by **RobW** » 15 Apr 2005, 15:19

Heater control now sorted ! turned out to be a fault in the cabin sensor, which is located in the front courtesy light housing. If you disconnect the orange plug, the heater works by taking the mean average from the other two sensors ( outside and engine temp ). A fault in the cabin sensor will also stop the first stage of the two speed fan kicking in, so your car will run at around 85 to 90 deg until the second stage kicks in. It cost me the price of a diagnostic test at main dealer (£63), to find out what was wrong.
A new sensor costs £88, scrappy charged me £5 for the whole courtesy unit.
Rob.