Heater Relay Circuit
- Remove A/C-heater control assembly, leaving harness connectors connected. See A/C-HEATER CONTROL ASSEMBLY under REMOVAL & INSTALLATION. Turn ignition on.
- Backprobe between terminal A18-2 (Blue/Yellow wire) of A/C-heater control assembly connector and ground. See Figure. If voltage is as specified, no problem is indicated at this time. See HEATER RELAY CIRCUIT SPECIFICATIONS table.
- If voltage is not as specified, remove heater relay. Check continuity between relay terminals. Continuity should exist between terminals No. 3 and 5, and between terminals No. 2 and 4. See Fig 1. Continuity should not exist between terminals No. 1 and 4.
- Using a fused jumper wire, apply battery voltage to terminal No. 3. Connect terminal No. 5 to ground. Continuity should exist between terminals No. 1 and 2. Continuity should not exist between terminals No. 2 and 4.
- If continuity is not as specified, replace heater relay. If continuity is as specified, inspect heater fuse, located in instrument panel fuse block. If fuse is okay, inspect wiring between A/C-heater control assembly and battery. Repair wiring as necessary. If fuse is blown, replace fuse and check for short circuit.
HEATER RELAY CIRCUIT SPECIFICATIONS
| Ignition Switch Position | Volts | |
|---|---|---|
| Off | 0 | |
| On | ||
| Blower On | 0 | |
| Blower Off | Battery Voltage | |