Temperature Regulation

IHKA E32 TEMPERATURE REGULATION







As on IHKR systems, IHKA regulates cabin temperature by regulating heater core temperatures. The control module pulses electrically-actuated valves to control hot coolant flow through the cores. The valves are held open by springs, and close when they receive power pulses.

The control module pulses the solenoid valves according to the Y-factor; which is calculated from the following inputs:
- Left desired temperature
- Right desired temperature
- Interior temperature
- Left heater core temperature
- Right heater core temperature
- Ambient air temperature Blower thumbwheel position

When the left desired temperature thumbwheel Is rotated all the way to the right (maximum heating), temperature regulation is cancelled and the valves remain 100% open to provide maximum heat output.

Similarly; when the left temperature thumbwheel is rotated all the way to the left (maximum cooling) the control module keeps the valves closed for maximum cooling.

An electrically powered auxiliary coolant pump (mounted in the engine compartment, near the brake booster) is used to ensure an adequate supply of hot water to the heater cores at all times. The control module keeps the auxiliary coolant pump off:
- Following a cold start, until one of the heater cores reaches 86 °F (30 °C), and
- Until the left or right Y-factor reaches 30%







Once the pump is started, the control module keeps it operating until the left or right Y-factor drops below 25%.