System Operation

The actual operation of the climate control system depends on three factors:
- Interior temperature from inside temperature sensor
- Outside temperature from evaporator temperature sensor
- "Set temperature" on control head selected by the driver


A frequency generator in the control head generates a different voltage signal for each temperature setting.

This output signal is supplied to both temperature sensors before going to the programmer. Based on their temperature and resistance, the sensors will correct this signal.


The programmer then compares the corrected signal with the actual value for the "set temperature." The programmer will then operate the necessary components to reach and maintain the "set temperature."






Cooling
If the interior is hot and the "set temperature" is 72°F (22°C) the system will operate as follows when the Auto button is pushed:
- The recirculation door will open and recirculate the interior air for fast "cool down."
- The heater control valve will close and no hot water will circulate through the heat exchanger.
- The majority of air distribution will be through the dash vents.
- The heater control flap will be closed so no air can flow through the heater core.
- Blower speed will accelerate from zero to high over a 10 second interval.

As the car's interior begins to cool down the recirculation door will close, allowing outside air in the system. The heater valve will also open and if needed, the temperature control doors will open allowing some of the air f0 be heated. The blower speed will also gradually be reduced and the air coming from the dash vents will warm.up slightly.

On a very hot day the system may operate in the max cold range for a long time. On milder days the system may operate in the intermediate temperature range.






Heating
If the interior of the car is very cold and the 'set temperature" is 72°F (22°C) the system will operate as follows when the Auto button is pressed.
- The recirculation door will open and outside air will flow into the system.
- The heater control valve will open and hot water will flow through the heater core.
- The heater control flap will open fully so all air flows past the heat exchanger.

If engine temperature is below iO4°F (4O°C) the blower fan will not run. Once engine temperature reaches 1O4°F (4O°C) the fan will accelerate from zero to high over a ten second interval. Air distribution will be mainly through the floor vents with a slight flow through the defrost vents.

As the interior temperature warms up the temperature control doors will close slightly to let some air bypass the heat exchanger. Air will also begin to flow through the dash vents and the blower speed will decrease.