System Overview

SYSTEM OVERVIEW
Temperature settings should be used as guides only. To set a temperature, press either the "Cool" or "Warm" button. Hold it until you see the desired temperature displayed. The reading will change one degree at a time spaced a half second apart.

The "Cool" button will go down to 18°C (65°F). If you press it again you see 18°C (65°F), the setting will jump down to 15°C (60°F) and stay there. From that point, the system will cause maximum cooling. This will override automatic control.

The "Warm" button will go up to 29°C (85°F). If you press it again after you see 29°C (85°F), the setting will jump up to 32°C (90°F) and stay there. From that point, the system will cause maximum heating. This will override automatic control.

All Electronic Climate Control (ECC) systems use an electronically-operated, rheostat-controlled motor to position the temperature door. The ECC system electrically activates the automatic, bi-level, economy, heater and defogger/defroster modes through the use of vacuum solenoids located in the programmer.

The Heater-Vent-Air Conditioning (HVAC) system's control components include: an A/C control head assembly (controller), programmer assembly, the blower power control module, an in-vehicle temperature sensor, an outside air sensor and the air distribution assembly containing the air flow control valves, the evaporator and heater core. Combined with the cycling clutch orifice tube (CCOT) refrigeration system, the controller regulates blower fan motor speed and generates command signals addressed to the programmer and blower power control module.

An LED indicator goes "ON" when an operating mode button is pressed. By pressing specific buttons, the operator can select the desired HVAC operating mode(s) or temperature settings for:

^ One of the five operating modes (Heater, Economy, Automatic, Bi-Level and Defogger/Defroster)
^ WARM or COOL
^ Two blower settings: auto, manual 0-10
^ Rear window defrost (R. DEF)
^ "OFF"

A flashing LED indicator on the ECC faceplate is the first indication that the microprocessor has sensed a problem with the system. Flashing occurs only once, for approximately 60 seconds, during every driving session until the problem has been corrected.

The ECC HVAC system performs normally within an input voltage range from 9 Volts DC to 16 volts DC. Its Micro Processor Unit (MPU) can retain data in the non-volatile Read Only Memory (ROM) down to a battery voltage as low as 4.15 Volts DC. When the ECC system or the vehicle has been shut "OFF", the MPU draws a low-standby current of less than 10 milliamps to retain the contents of its Random Access Memory (RAM).

OFF - In this setting, the fan blower motor or the air conditioner compressor will not run. The system will try to reach the setting selected. If 21°C (70°F) is selected and it is a cold day, the vehicle's interior will reach the 21°C (70°F) range; but it will take longer because the fan is not running. If it is a hot day, the interior will cool but only down to about half that of the outside temperature. This 21°C (70°F) setting will force all air to the floor outlet in the vehicle.

HTR (HEATER-ECONOMY) - With this setting, all air entering the vehicle is forced to the floor. The fan blower motor will vary in speed unless the "down" or "up" button is pressed. In-vehicle temperature will adjust to the setting selected, unless the temperature selected is below the outside temperature.

ECON (ECONOMY) - The compressor will not run in this setting. The system will adjust to the temperature selected. It cannot cool the vehicle colder than the outside temperature. This setting decides automatically the fan blower speed and air outlet positions by the different inputs already mentioned unless the fan is overridden by the down or up push buttons.

AUTO (AUTOMATIC) - In this setting, everything is controlled by the inputs already discussed. The system will adjust to the temperature range selected, and it will remain stationary. The fan blower will vary its speed on its own unless it is changed with the "down" or "up" push buttons.

BI-LEV (BI-LEVEL) - By using this setting, the system will let air into the vehicle only through the (hi-level) heater and air conditioner outlets. This setting will bring the temperature to the range Selected. It will control fan blower speed by using the input signals from the ECM and individual sensors. It also operates windows. The fan blower speed can be adjusted by using "down" or "up" push buttons.

DEF (DEFOGGER/DEFROSTER) - With this setting, all air is forced to the windshield. The compressor runs by using all the input signals mentioned earlier. The fan blower will turn on to a high speed with no delay. After start-up, the "High" fan blower speed can be readjusted by pushing "down" or "Auto".

R. DEF (REAR DEFOGGER/DEFROSTER) - Use this setting to defrost or defog the rear window. The first time the button is pressed, the unit will run for ten minutes. Then the unit will shut "OFF." After it has been warmed up, it will run for five minutes when reactivated.

At ignition, a small amount of air flow is directed to the floor. This purges the heater core and prevents the windshield from fogging. The purge mode duration lasts for 15 seconds and is enabled when the program number is above a given value. If a blower delay is required, the purge mode is entered at the completion of the delay.

Entering manual blower or the front defrost mode will override the purge mode.

(LOW) FAN - This setting will override automatic fan speed. To decrease fan speed, press the "down" button and hold until the selected fan speed is displayed If heat is required, a timer delay will keep the fan "OFF" for three minutes on cold start-ups.

AUTO (AUTOMATIC) FAN - If this setting is selected, the controller will choose the fan speed based on the input signals talked about earlier.

(HIGH) FAN - This setting overrides automatic fan speed. To increase fan speed, press the "up" button and hold until the selected fan speed is displayed. There is no fan blower delay.

EXT TEMP (EXTERIOR TEMPERATURE) - By pushing this button, the readout in the control head will show the outside temperature instead of the vehicle's inside temperature. Push the "EXT TEMP" button again to return to the normal readout (or press either "Cool" or "Warm"). Turning the ignition "OFF" and back "ON," will cause the readout to go back to the vehicle's interior temperature.

For optimum system performance with top removed and/or windows down, use manual control or fan speed.