Planning the next
AO Silver Member
Join Date: May 2007
Location: United Kingdom
The phase 2 has a permanently live heater matrix i.e. hot water constantly flows through it. Incoming air is channelled depending on the heat in the cabin and the heat of the air in the vents and, to some extent, the ambient temperature.
So, if the cabin is colder than the selected temperature, a motor moves a flap to channel the incoming air through the heater matrix. If the cabin is too hot, then air is channelled away from the heater matrix and is either at ouside temp if the air con is off, or chilled if the aircon is on.
There are three areas you need to look at.
1. There are two mixed air temperature sensors. One for the footwell and the other for face/screen vents. So your first test is to establish if you can get cold air by sending all the air to the footwell and then the screen. If you can get cold air one way but not the other, then one of the air mix sensors has a problem.
2. The external air temperature sensor. This is the black blob underneath the passenger door mirror. Stick your thumb over it to warm it up and see if you can get cold air out of the vents. The sensor takes a while to react to changes so leave your thumb on it for a minute or two. However, the car may choose to ignore the external air temperature sensor if the car is stationary!
3. The air mix motor. In order to mix the air through the heater or outside/aircon a flap is moved. The motor for this is behind the dashboard next to the driver's left knee. Remove the carpeted trim between the dash and the floor and with the ignition on ( engine off ), turn the temperature control to the extremes ( hot/cold ) and you should be able to hear the motor doing it's thing. This is best done with an ambient temperature about equal to the mid point on the scale ( 20°C ). For reference, play with the direction control as well ( screen/face/footwell )as the motor for that is in the same area as the mix motor and it'll give you an idea of what to listen for.
My inclination is that it is the mix motor that is at fault.