Temperature Regulation

IHKA E38 TEMPERATURE REGULATION







Temperature regulation on IHKA E38 is accomplished in exactly the same way as on earlier IHKA systems: solenoid actuated water valves, normally held open by spring pressure, are pulsed closed by the IHKA control panel/module to regulate coolant flow through the cores (and, thereby, the core temperatures).

The IHKA control panel/module pulses the water valves according to the following inputs:

- ambient temperature
- interior temperature
- left and right desired temperatures
- left and right heater core temperatures.







E38 vehicles also have an electrically powered auxiliary coolant pump to ensure that an adequate supply of hot water is always available to the heater cores. The control panel/module operates the pump directly (no relay), by supplying the ground circuit. Pump operating criteria are:

- Engine coolant temperature (ECT)* and Y-Factor -- ON with ECT >= 32°F (0°C) and left or right Y-Factor >= 5%; OFF with ECT < 32°F (0°C) and either Y-Factor < 0%, unless other inputs call for pump operation)

- Maximum defrost mode status -- ON when max. defrost is selected; OFF when max. defrost is turned off (unless other inputs call for pump operation)

- Maximum heating requested on left side of interior -- ON when max. heating is requested; OFF when max. heating is turned off (unless other inputs call for pump operation)

- "REST" function request -- ON when REST heating is requested; OFF when REST heating is turned off or "times out"

* Engine coolant temperature information is supplied to the control panel/module over the K-Bus.