Special Functions
SPECIAL FUNCTIONS
Like previous IHKA Systems, the E38 IHKA system control panel/module is programmed to perform some special functions automatically based on sensed inputs:
Cold Start Arrest
IHKA E38 includes an automatically activated cold start arrest function. The control panel/ module checks for the conditions necessary to activate the function at engine start-up:
- IHKA system turned "on" (left blower thumbwheel not in "0" position) and
- Maximum defrosting request is not present and
- Left Y-factor is 100% (maximum heating required) and
- Left side "AUTO" mode request is present and
- Left heater core temperature is less than 86°F (30°C).
If these conditions exist, the control panel/module will:
- Open the defroster flaps and
- Close all other air distribution flaps and
- Operate the blower motor, A/C compressor, fresh air flaps, and recirc. air flaps according to control panel/module settings.
When the left heater core temperature reaches 86°F (30°C), the cold start arrest function ends and all IHKA system functions depend upon control panel/module settings and sensed conditions.
Service-Station Feature
This function, introduced on IHKA E32, continues on IHKA E38. The control panel/module continues to power both coolant valves closed for about 3 minutes after the ignition is switched "Off. " This feature prevents the heater cores from being flooded with hot coolant when the engine is shut off for brief periods (e.g. during refueling).
"Rest" Feature
The "Rest" feature is a new feature, providing passenger compartment heating for a short time after the ignition is switched "Off." The feature is activated by pressing the "Rest" button on the control panel/module, if the following conditions are met:
- Ignition switch is "Off" and
- The ambient temperature is less than 59°F (15°C) and
- The left heater core temperature is greater than 158°F (70°C) and
- Battery voltage is greater then 11.4 volts and
- The time elapsed since the ignition was turned "Off" is less than 15 minutes.
Once the tunction is activated, the "REST" button LED illuminates, the blower runs at medium speed, the auxiliary coolant pump runs, and the air distribution flaps are positioned to provide maximum heating. Blower speed, flaps positions, and desired temperatures cannot be changed while the "Rest" function is active.
The system continues to run until any one of the following occurs.
- The ignition is switched "On" or
- Battery voltage drops below 11.4 volts or
- Coolant temperature drops below 86°F (30°C) or
- The "Rest" button is pressed again or
- 15 minutes pass.
The "Rest" function can also be activated when the ignition switch is in the "Accessory" position (KI.R). In "Accessory," blower speed, desired temperature, and air distribution can be changed, using the control panel/module rocker switches, thumbwheels, and buttons.
Remote Recirculated Air
The E38 multi-function steering wheel contains a button which the driver can use to activate the recirculating air mode without taking his/her hands off the steering wheel. Note that almost all aspects of this function are performed using bus communication.
Automatic Recirculated Air (AUC)
If the driver presses the recirculating air button once, the control panel/module takes over control of recirculating air mode. The control panel/module uses data from the AUC sensor to determine whether recirculating air mode is necessary.
The AUC sensor, located in the lower right corner of the fan shroud, samples ambient air that has entered the engine compartment. The sensor contains a gas sensor, which measures the level of oxidizable gases in air. These include hydrocarbons, NOx, SOx and CO. The AUC sensor sends a voltage signal to the control panel/module according to the concentration of these pollutants.
If a high level of pollutants is detected, the control panel/module activates the recirculating air mode as follows:
- In heating mode, recirculating air is used for a maximum of 3 minutes.
- In cooling mode, recirculating air is used for a maximum of 10 minutes.
If the level of oxidizable gases drops to an acceptable point before the time limit is reached, the IHKA system switches back to fresh air intake. If air quality has not improved at the end of the time limit, the system switches to fresh air briefly and then back to recirculating mode for another 3 or 10 minute period.