Temperature control mystery

mike.evans · 9th July 2009, 12:35

When I turn on any function on the heating / aircon on my 1999 75 connoisseur 2.5 the temperature on both sides reads 22'C, then immediately changes to an "er" error message. This stays there even when turned off and only goes away completely when the ignition is switched off.
All the functions seem to work but seem to be fixed at one temperature,which I assume is 22'C.
The only related issue is that the rear window heater seems to have stopped working at the same time.
I have:

checked fuses and relays for rear heater
done a battery reset
changed the aircon ECU

Any ideas most welcome

Greeners · 9th July 2009, 12:47

check for water in the plenum

if dry, find a member close to you and swap control panels...

Departed · 9th July 2009, 18:55

Check the fuses for the ATC panel itself.

My guess is the ignition feed is OK, but there's a permanent feed too. This is used to remember your settings when the ignition is off, but will also be used for other things, for example closing the recirc flap when you switch the ignition off (that funny whirring sound). Could easily explain your symptoms.

Edit:

In fact there are three. Permanent (fuse 4) auxiliary (fuse 33) ignition (fuse 11).

All based on workshop manual for an original version so check your handbook.

Mike · 9th July 2009, 19:25

In addition to the good advice above it may be worth running the ATC diagnostics routine. Details here:

http://www.the75andztclub.co.uk/foru...hread.php?t=46

hth

mike.evans · 9th July 2009, 22:04

Thanks to everyone for the great advice. I think I will try them all tomorrow

9th July 2009, 12:35	#1
mike.evans Newbie Rover 75 2.5 V6 Connoisseur se Join Date: May 2008 Location: Somerset Posts: 24 Thanks: 0 Thanked 0 Times in 0 Posts	Temperature control mystery When I turn on any function on the heating / aircon on my 1999 75 connoisseur 2.5 the temperature on both sides reads 22'C, then immediately changes to an "er" error message. This stays there even when turned off and only goes away completely when the ignition is switched off. All the functions seem to work but seem to be fixed at one temperature,which I assume is 22'C. The only related issue is that the rear window heater seems to have stopped working at the same time. I have: checked fuses and relays for rear heater done a battery reset changed the aircon ECU Any ideas most welcome

9th July 2009, 12:47	#2
Greeners Moderator MG-ZTT Join Date: Mar 2007 Location: Ware, Herts Posts: 19,798 Thanks: 161 Thanked 1,249 Times in 1,036 Posts	check for water in the plenum if dry, find a member close to you and swap control panels... __________________ *David* Impecunity is the mother of ingenuity Useful how to's for common problems Car Of The Month Jan 2014 [SatNav Power Down] [Coolant Level] [SatNav Repair] [Diesel Non Starting] [Paint Codes] [Rear Light Seals] [Reversing Light Switch] [Bleeding Brakes][Sunroof Drain] [Early ZT's][Instrument Pack Diagnostics][ATC Diagnostics]

9th July 2009, 18:55	#3
Departed Retired -- Join Date: Jan 2007 Location: -- Posts: 3,785 Thanks: 0 Thanked 4 Times in 4 Posts	Check the fuses for the ATC panel itself. My guess is the ignition feed is OK, but there's a permanent feed too. This is used to remember your settings when the ignition is off, but will also be used for other things, for example closing the recirc flap when you switch the ignition off (that funny whirring sound). Could easily explain your symptoms. Edit: In fact there are three. Permanent (fuse 4) auxiliary (fuse 33) ignition (fuse 11). All based on workshop manual for an original version so check your handbook. Last edited by Departed; 9th July 2009 at 18:59..

9th July 2009, 19:25	#4
Mike This is my second home Rover 75 V8 Join Date: Oct 2006 Posts: 3,448 Thanks: 0 Thanked 206 Times in 32 Posts	In addition to the good advice above it may be worth running the ATC diagnostics routine. Details here: http://www.the75andztclub.co.uk/foru...hread.php?t=46 hth __________________ Mike [SIGPIC][/SIGPIC]

9th July 2009, 22:04	#5
mike.evans Newbie Rover 75 2.5 V6 Connoisseur se Join Date: May 2008 Location: Somerset Posts: 24 Thanks: 0 Thanked 0 Times in 0 Posts	Thanks to everyone for the great advice. I think I will try them all tomorrow