Hi
when the heater is on hot all the time, is the control faulty or is the heater flap open? Control seems to increase/decrease temperature as should.
How do I start checking for the control or the flap.
Deon
Thema Series II heater stuck in hot position
Re: Thema Series II heater stuck in hot position
Hi,
You can use the autodiagnosis to check,
Ignition off,
push and hold the automatic button and switch on ignition
The three centre LEDs should come on.
Press automatic
Press Air -, This should show temperature of air inside the cabin on RH display (Max error +/-1C, if 44 or 93 =short circuit)
Press Air +, This should show temperature of air outside the cabin on RH display (Max error +/-1C, if 51 or 63 =short circuit)
Press Temperature -, This shows temperature (C) of air inside mix unit (Max error +/-1C, if 01 or 83 =short circuit)
Press Temperature +, This shows the position of the distribution flap in the RH display
Press automatic
Press Air -, This moves the distribution flap to the closed position (Position display is in Hex decreasing)
Press Air +, This moves the distribution flap to the open position (Position display is in Hex increasing)
You can check distribution flap movement by the lever on the RH of the fan unit
Press automatic to return to normal
In checking the sensors if zero resistance = broken cable, if infinite resistance broken sensor.
Paddy
You can use the autodiagnosis to check,
Ignition off,
push and hold the automatic button and switch on ignition
The three centre LEDs should come on.
Press automatic
Press Air -, This should show temperature of air inside the cabin on RH display (Max error +/-1C, if 44 or 93 =short circuit)
Press Air +, This should show temperature of air outside the cabin on RH display (Max error +/-1C, if 51 or 63 =short circuit)
Press Temperature -, This shows temperature (C) of air inside mix unit (Max error +/-1C, if 01 or 83 =short circuit)
Press Temperature +, This shows the position of the distribution flap in the RH display
Press automatic
Press Air -, This moves the distribution flap to the closed position (Position display is in Hex decreasing)
Press Air +, This moves the distribution flap to the open position (Position display is in Hex increasing)
You can check distribution flap movement by the lever on the RH of the fan unit
Press automatic to return to normal
In checking the sensors if zero resistance = broken cable, if infinite resistance broken sensor.
Paddy
Re: Thema Series II heater stuck in hot position
Sorry this is a bit late - couldn't remember my login
Most likely is the motor that drives the heater control is stuck - in the middle of the dash, behind the vents is a frame with some electric stepper/wiper motors on it. One opens/shuts the heater tap (a bit at a time) the other selects where the heat/air should go. With the ignition on (motor off) and fan off you should be able to hear these motors working. If, when you change the temperature, you don't hear the motor stepping, then the motor is stuck, which would explain why the heater is always on.
I had some success by dismantling the motor and wiper assembly, cleaning everything and reassembling it again. Both of my Themas had one of these motors fail - don't buy a new one as they are VERY expensive.
David
Most likely is the motor that drives the heater control is stuck - in the middle of the dash, behind the vents is a frame with some electric stepper/wiper motors on it. One opens/shuts the heater tap (a bit at a time) the other selects where the heat/air should go. With the ignition on (motor off) and fan off you should be able to hear these motors working. If, when you change the temperature, you don't hear the motor stepping, then the motor is stuck, which would explain why the heater is always on.
I had some success by dismantling the motor and wiper assembly, cleaning everything and reassembling it again. Both of my Themas had one of these motors fail - don't buy a new one as they are VERY expensive.
David
Re: Thema Series II heater stuck in hot position
Hi,
I have experienced exactly the same trouble and the cause was a broken flap that controls the air mixture. This flap lives within the fan housing. It was a dog to fix, as the fan housing had to come out, which was possible only after taking out the main A/C unit (the big thing in front of the driver (RHD). In my case, this meant replacing the fan housing, as the flap also broke a small part of the fan housing, so the new flap could not sit in properly. Do check the stepper motors, though, (easy job) before taking everything apart to get to the flap (really big job, cost me a whole weekend with the bonnet up!)
I have experienced exactly the same trouble and the cause was a broken flap that controls the air mixture. This flap lives within the fan housing. It was a dog to fix, as the fan housing had to come out, which was possible only after taking out the main A/C unit (the big thing in front of the driver (RHD). In my case, this meant replacing the fan housing, as the flap also broke a small part of the fan housing, so the new flap could not sit in properly. Do check the stepper motors, though, (easy job) before taking everything apart to get to the flap (really big job, cost me a whole weekend with the bonnet up!)