Heating and Air Conditioning: Description and Operation

The A/C-Heater System is powered by a 10A fuse 7 and 30A Fuse 9 of the Interior Fuse Panel which are both hot with the Ignition Switch in the RUN position and 50A Maxi-fuse 3 of the Power Distribution Box, which is hot at all times.

Blower

With the Ignition Switch in the RUN position, current flows from the 30A Fuse 9 to the Blower Motor. The speed of the Blower Motor is controlled by the Blow Motor Control Switch and the Blower Motor Resistor.

When the Blower MOtor Control Switch is in the HI position, the Blower Motor is grounded for full speed operation. In any other "ON" position (1, 2 or 3) current flows through the Blower Motor Resistor, which controls the amount of current that flows through the Blower MOtor with one, two or three resistors.

A/C-Heater

The A/C System can be turned ON by activating the A/C Switch located at the Blower Motor Control Switch. Current will then flow from the 10A Fuse 7 through the closed A/C Switch to the A/C Pressure Cycling Switch. The Clutch Pressure Cycling Switch cuts off power to the A/C Clutch Field Coil with low suction pressure. Current will then floe from the Clutch Cycling Pressure Switch to the WOT Relay. The WOT Relay is controlled by the EEC and is energized until wide open throttle occurs. With the A/C Switch closed, the Clutch Cycling Pressure Switch closed and the WOT Relay energized, current will flow to the Compressor Clutch Field Coil circuit which allows the engine to drive the compressor.