Drivers side heater not getting hot

[krio1987]

Hi there, I have a citroen c4 grand picasso mk 2 (66 reg). I've recently encountered a weird issue with the heater. The heater doesn't get hot on the drivers side but does on the passenger side. Does anyone know how this is possible and what I can check. I'm wondering if it's a fuse or motor blown or something, but need some guidance on where to look.

Many thanks

Adam

[PaulC5]

Are you saying the matrix is not getting hot at each end or you are not getting hot air out of vents at both sides of the dash ? If the former then the matrix may be blocked. If the latter then if you have climate control with separate control of driver and passenger side, then the warm air flap at the driver side may not be moving due to a flap fault or motor fault or controller fault - can you hear the flap moving as you adjust the temperature ? Could also be debris blocking the matrix such as leaves if the cabin filter has a hole in it if you are not getting the air flow.

[krio1987]

Hi Paul,

Thanks for coming back.

My apologies for not being clear previously. Hot air comes out of the passenger side when on HI, but cold air comes out of the drivers side even when on HI. The vehicle does indeed have climate control.

I've just been out to the car and without the car running, I've cycled between LO and HI, I can hear subtle movement underneath the dash as I get down to LO and as I get to a third of the way towards HI. I've compared the noise between the drivers and passengers and I would say it sounds the same. So I think something is moving, but whether it's moving enough I can't be sure from the noise.

Many thanks
Adam

[myglaren]

The flaps distort with the heat and jam, which then strips the plastic gears that move the flaps.

[RichardW]

Matrix blockage on these is common, and affects (in RHD) the driver's side first, as the supply is from the passenger side. It's a relatively easy job to swap the matrix, as it's accessible from the passenger footwell - the hardest part is getting the pipe clamps back on - and water tight!

[myglaren]

Perhaps a flush using Liquimoly or Forte cooling system cleaners would suffice.

[krio1987]

Hi guys, thanks for coming back, the matrix was replaced last year with a brand new one. So I would be surprised if it was that, maybe a flush will do, I plan o. Taking the facia panels off and having a look at the flaps/motors at some point to see if it’s that. Otherwise a flush though might make sense here. Then i guess the last resort would be the matrix? I think this model has an auxiliary matrix, do you think that might have anything to do with it?

[PaulC5]

If you can get access to the matrix see if both ends are hot then you can forget about it.