Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Did you review the HVAC operation and perform the necessary inspections? | -- | Go to Step 2 | Go to Symptoms |
2 |
Does the test lamp illuminate? | -- | Go to Step 3 | Go to Step 4 |
3 | Connect a test lamp between CKT 1596 (GRY/BLK) terminal A and CKT 850 (BLK) terminal B at the water bypass valve solenoid. Does the test lamp illuminate? | -- | Go to Step 5 | Go to Step 6 |
4 | Using a test lamp backprobe from the rear heater switch CKT 1596 (GRY/BLK) terminal C to ground while moving the rear heater switch between LOW, MEDIUM, and HIGH. Does the test lamp illuminate in all of the settings? | -- | Go to Step 7 | Go to Step 8 |
5 |
Do any restrictions or damage exist? | -- | Go to Step 9 | Go to Step 10 |
6 | Repair the open in CKT 850 (BLK). Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 15 | -- |
7 | Repair the open in CKT 1596 (GRY/BLK). Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 15 | -- |
8 | Inspect for a poor connection at the rear heater switch. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems. Does a poor connection exist? | -- | Go to Step 14 | Go to Step 11 |
9 | Repair or replace the vacuum supply hose as necessary. Refer to Vacuum Hose Harness Replacement in Heating, Ventilation, and Air Conditioning. Did you complete the replacement? | -- | Go to Step 15 | -- |
10 |
Do any conditions exist? | -- | Go to Step 12 | Go to Step 13 |
11 | Replace the rear heater switch. Refer to Control Switch Replacement - Auxiliary in Heating, Ventilation, and Air Conditioning. Did you complete the replacement? | -- | Go to Step 15 | -- |
12 | Repair or replace the rear heater core. Refer to Auxiliary Heater Core Replacement in Heating, Ventilation, and Air Conditioning. Did you complete the repair? | -- | Go to Step 15 | -- |
13 | Replace the water bypass valve solenoid. Refer to Heater Water Bypass Valve Replacement in Heating, Ventilation, and Air Conditioning. Did you complete the replacement? | -- | Go to Step 15 | -- |
14 | Repair the poor connection at the rear heater switch. Refer to Connector Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 15 | -- |
15 | Operate the system in order to verify the repair. Did you correct the condition? | -- | System OK | Go to Step 2 |
