Initial Inspection and Diagnostic Overview

Operational Check
The purpose of the operational check is to confirm that the system operates properly.

Conditions : Engine running and at normal operating temperature

CHECKING BLOWER
1. Turn blower control dial clockwise. Blower should operate on low speed.
2. Turn the blower control dial again, and continue checking each blower speed until all speeds are checked.
3. Leave blower on speed 4.

If NG, go to trouble diagnosis procedure for MTC-59, "Front Blower Motor Circuit". Front Blower Motor Circuit
If OK, continue with next check.

CHECKING DISCHARGE AIR
1. Turn the mode switch to each position.
2. Confirm that discharge air comes out according to the air distribution table.

Mode door position is checked in the next step.
If NG, go to trouble diagnosis procedure for MTC-47, "Mode Door Motor Circuit". Mode Door Motor Circuit
If OK, continue with next check.

NOTE: Confirm that the compressor clutch (with A/C) is engaged (sound or visual inspection) and intake door position is at fresh when the DEF or D/F is selected.




DISCHARGE AIR FLOW

CHECKING TEMPERATURE DECREASE
1. Rotate temperature control dial counterclockwise.
2. Check for cold air at appropriate discharge air outlets.

If NG, listen for sound of air mix door motor operation if OK, go to trouble diagnosis procedure for for MTC-72, "Insufficient Cooling". Insufficient Cooling If air mix door motor appears to be malfunctioning, go to MTC-53, "DIAGNOSTIC PROCEDURE FOR AIR MIX DOOR MOTOR". Air Mix Door Motor Circuit

If OK, continue with next check.

CHECKING TEMPERATURE INCREASE
1. Rotate temperature control dial clockwise.
2. Check for hot air at appropriate discharge air outlets.

If NG, listen for sound of air mix door motor operation. If OK, go to trouble diagnosis procedure for MTC-79, "Insufficient Heating" Insufficient Heating. If air mix door motor appears to be malfunctioning, go to MTC-53, "DIAGNOSTIC PROCEDURE FOR AIR MIX DOOR MOTOR (FRONT)". Air Mix Door Motor Circuit

If OK, continue with next check.

CHECK A/C SWITCH (IF EQUIPPED)
1. Press A/C switch with the blower control dial set to 1.
2. A/C switch indicator will turn ON.
- Confirm that the compressor clutch engages (sound or visual inspection).

NOTE: If current mode setting is DEF or D/F compressor clutch may already be engaged.

If NG, go to trouble diagnosis procedure for MTC-67 "Magnet Clutch Circuit". Magnet Clutch Circuit

If OK, continue with next check.