A/C System - Electrical Troubleshooting
89mazda04Category Applicable Model/s
16 1986-1988 323
Subject Bulletin No. 038/89
A/C SYSTEM TROUBLESHOOTING Issued 6/6/89
Revised
DESCRIPTION
The purpose of this Service Bulletin is to explain basic operation and troubleshooting of the electrical portion of A/C systems. If a customer complains about an inoperative A/C system, perform the appropriate troubleshooting according to the information in this bulletin.
BASIC A/C OPERATION
1. When the A/C Switch and Blower Switch are turned on, the ground circuit of E.G.I. Control Unit 1L terminal is completed through the Thermo Switch.
2. When the 1L terminal of E.G.I. Control Unit is grounded, the E.G.I. Control Unit grounds the coil side of No.1 A/C Relay through 1F terminal and turns the No.1 A/C Relay on.
3. No.1 A/C Relay supplies battery power to the Magnetic Clutch of the A/C Compressor through the Pressure Switch. At the same time, No.1 A/C Relay supplies battery power to the No.2 A/C Relay to complete the ground circuit for the Condenser Fan.
4. While the engine is turned over (cranking), battery power is applied to the ground side of the IG Relay which makes the IG Relay turn off, and battery power to the Magnetic Clutch, Blower Motor, etc. is cut off in order to reduce the cranking load of the starter motor.
TROUBLESHOOTING (A/C DOES NOT TURN ON)
NOTE:
Before performing the following troubleshooting, check the A/C fuse (15A), circuit breaker (at joint box) and main fuse.
1. With the IG Switch on and Blower Switch in the 1st position, turn the A/C Switch on and check if the Condenser Fan comes on.
^ If the Condenser Fan operates, check the continuity of the Pressure Switch or check for an open circuit between the No.1 A/C Relay and Magnetic Clutch.
^ If the Condenser Fan does not operate, go to Step 2.
2. With the engine running and A/C Switch and Blower Switch on, ground the "W" wire at No.1 A/C Relay connector and check if the A/C comes on.
^ If the A/C operates, go to Step 3.
^ If the A/C does not operate, go to Step 4.
3. Ground the 1L terminal of the E.G.I. Control Unit and check if the A/C comes on.
^ If the A/C operates, check the continuity of the Thermo Switch, A/C Switch, Blower Register and Blower Switch or check for an open circuit in the connectors for the above components.
^ If the A/C does not operate, ground the 1F terminal and check for A/C operation.
A/C operates: Replace E.G.I. Control Unit
A/C does not operate: Repair the open circuit between No.1 A/C Relay and 1F terminal
4. Check the voltage of the two (2) Blue wires of the No.1 A/C Relay connector.
^ 12 volt is applied to both terminals: Replace No.1 A/C Relay
^ 12 volt is not applied to either or both terminals:
To check for the open circuit, SEE IMAGE.