Heater only hot one side - cold the other

[Derek Wilkins]

Hello. I'm the new owner of a 2016 new model Proace.  The heater works reasonably ok on passenger side but only blows cold on the drivers side.  It's not a dual system so is it the internal flaps playing up?  The lower stepper motor also seems u/s (which is the heat regulator?) as it doesn't move on any setting.  Manually moving that flap also makes no difference to temperature.  Screen/face/floor settings are all cold on drivers side.  No apparent air lock.  Any ideas?

[Bper]

Hi Derek,

The servo motor under the dash may be faulty and is not opening the flaps. Check the connection and disconnect the servo motor and move the flaps manually if the heat comes through its the servo. Also check coolant levels if they ate to low it will affect the heater. Hope this helps

[Derek Wilkins]

Hi Bob

 Yes, my thought is it's the lower stepper motor as it doesn't operate on any setting. I've removed it pending a replacement but manually moving the lower flap still doesn't affect the temperature.  I've checked water level and also bled the heater - but still no driver's side heat (!).  I've noticed this same fault has been reported on the Peugeot forum - but can't find any answer there!!   Seems it must be a blockage or a faulty flap issue - but why just one side, if it's not a dual system???   Ideas anyone 🤔

[Bper]

Hi Derek,

Have you tried a scan tool to see if any codes come up. It's a bit of a strange one but quiet common apparently. Loose connection on AC controls. Faulty resistor. blocked heater core, disconnecting and reconnecting the Battery can help as it can sometimes  reset the problem.

If it was me I would try a scan tool first, if this shows no codes and you do not have sufficient skills to go through the heating system. It may be easier to let a garage take a look.  ☺️

IMO sometimes it saves the grief.

 

[Bper]

Hi Derek,

Have a look at this link it may help with resolving the problem. 

https://www.toyotanation.com/threads/heat-only-works-on-passenger-side-please-help.1685744/

[Derek Wilkins]

Hi Bob

Thanks again for your input!  Looks like a bit more research on my part! 

Replacement stepper motor is 'in the post' so can't do much until it arrives - but in the meantime I'll digest what you've sent so that I can get my head around exactly how the system works & try a few of the suggestions...!

I'll let you know where I end up!

Ps basic scan shows no errors.... 😉

[dvlpr]

Hi Derek did you find a solution for this?

Have a 2017 proace myself and its getting too cold to drive nowadays.