Test H: Insufficient, Erratic Or No Heat

PINPOINT TEST H: INSUFFICIENT, ERRATIC OR NO HEAT

H1:

H2-H5:

H5-H8:

H9-H10:

Normal Operation
Under normal operation, the coolant control valve receives battery voltage through circuit 30-FB3 (RD/OG). The coolant control valve is provided a ground through circuit 91S-FB3 (BN/BL)/91S-FB3 (BK/OG) and/or 91S-FB4 (BN/GN) from the dual automatic temperature control (DATC) module, depending on which side of the heater core warm coolant is to flow through.

Possible Causes
- An open in circuit 30-FB3 (RD/OG), 91S-FB3 (BN/BL), 91S-FB3 (BK/OG) or 91S-FB4 (BN/GN)
- A short to ground or voltage in circuit 91S-FB3 (BN/BL), 91S-FB3 (BK/OG) or 91S-FB4 (BN/GN)
- Coolant control valve
- DATC module
- Evaporator discharge air temperature sensor
- Thermostat