Auto. A/C Systems: Operation
ELECTRONIC CLIMATE CONTROL SYSTEM PERFORMANCE (Engine Warm and Idling)
| Control Settings | Temp. | System Should Operate as Follows |
|---|---|---|
| FRT DEF | 90° | Warm air should be delivered from defroster outlets at a fixed high blower speeds Minor floor bleed from heater outlet. |
| HI | 90° | Warm air should be delivered from the heater outlet with only a small amount from the defroster outlets. The blower should stay at high speed. |
| AUTO | 75° | After a short delay, the blower speed should gradually decrease. Discharged air should become cooler Depending: on the temperature in the work area, the air delivery mode should change to A/C outlets from the heater outlets. The intermediate delivery mode is defrost when this transition occurs. |
| AUTO | 60° | Blower speed should increase to a fixed high value. Discharged air should become maximum cold. The air inlet door should slowly open (signalled by blower noise increase}. |
| LO | 60° | After a short delay, the blower speed should gradually decrease to a very low value. The discharged air should remain cold and come from the A/C outlets. The air inlet door should slowly close. |
| ECON | 60° | The A/C compressor should be off. Blower speed should gradually increase to a fixed high value. Discharged air should continue to come from A/C outlets and should be warmer than the temperature in the work area. |
| OFF | 60° | Blower is off. Minor defroster and heater bleed when driving. |
| RR DEF | NONE | LED above button should light up. Heat should be applied to rear window. |
| OUTSIDE TEMP | NONE | LED to left of button should light up and outside temperature displayed on control panel. |
Electronic controls drive a reversible DC motor which positions the air mix door in response to temperature changes and control settings. The sequence of events as the programmer moves from maximum A/C to maximum heat is as follows:
- Possibility of recirculated air is terminated.
- Heater water valve opens.
- Blower speed gradually decreases from Hi to Low.
- Air-Mix door starts to move and blends in hot air.
- Mode of air delivery changes from A/C to heater.
- Blower speed increases gradually from Low to Hi.
- Air-Mix door reaches "Max Heat" position.
The sequence of events is reversed as the programmer moves from maximum heat to maximum A/C.