33
E46 Climate Control
The Y-factor of the E46 IHKR is determined by:
• Setting of the temperature control dial
• Outside temperature (from Kombi via the K-bus)
• Heater core temperature
Automatic temperature control is switched off when the temperature control dial is turned
all the way to the left (blue: water valve closed) or right (red: water valve full open) stop.
Each step of the potentiometer represents a temperature from max. cold (10
o
C) to max.
warm (49.5
o
C). This temperature value is combined with the outside temperature to form
a calculated set-point. The E46 IHKR does not use an interior temperature sensor.
The Y-factor is then determined by comparing the calculated set-point to the actual value
of the heater core sensor which is in the stream of air to the outlet ducts.
In addition to the Y-factor, the control unit evaluates coolant temperature and engine RPM
to determine water valve opening time. The valve opening times are:
• 0 ms at max. COLD
• 3600 ms at max. WARM
Engine map cooling
Map cooling is used by the DME MS 43.0 for the M54 engines. This can create very high
coolant temperatures which could be damaging to the climate control system. If the heater
core temperature exceeds 80
o
C, the water valve is closed until the temperature drops
below 80
o
C.
If the temperature at the heater core increases above 93
o
C (i.e. water valve faulty), the IHKR
will signal the DME (via K-bus/Kombi/CAN) to energized the map cooling thermostat.
Service Station Feature
The service station feature prevents the vehicle occupants from getting a blast of hot air
after the vehicle is restarted following a short stop. The water valve is powered closed by
the IHKR control unit for three minutes after shut-off. This prevents the heater core from
being flooded with hot coolant.
To Next Page
Loading...
Need help?
General
