Air Conditioning Blows Warm Air

The air conditioning may blow warm air on some 2021-2022 Tahoe, Suburban, Yukon and Escalade models. The Check Engine MIL may be illuminated and DTCs B1AA3 (Run/Crank Relay Coil Control), U3018 (Control Module Input Power Circuit 1/2 Correlation) and U3505 (Control Module Input Power 2 Circuit Low Voltage) may be set.

These conditions may be the result of circuit 4786 in the front floor console compartment lamp shorting out, opening the BCM 2 fuse F4DR. If the cause is not found after following the Service Information diagnostics for any DTCs set, access the front floor console lid hinge area to inspect the wiring for the console compartment lamp. (Fig. 3)


Fig. 3


In some cases, the two circuits to the compartment lamp will be broken and shorted together. (Fig. 4) Repair any damaged circuits following the wiring repairs in the appropriate Service Information.


Fig. 4


For additional information about wiring repairs, refer to Bulletin 10-00-89-005.


– Thanks to Jim Will

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