Try this...
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Turn ignition switch to RUN position.
Push both SEEK and PRESET 3 buttons simultaneously.
DIAG will be displayed.
Push PRESET 1 button.
Push TUNE button to scroll through the DTCs.
To exit self-test push SEEK .
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Please list any codes you get. My bet is the blower control module which does not set a code. To check out the blower speed control module do this....
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PINPOINT TEST H: A/C BLOWER MOTOR RUNS CONTINUOUSLY IN HIGH SPEED
H1 CHECK BLOWER OPERATION
Turn ignition switch OFF. Disconnect harness connector C2044 from the rear of the remote climate control module. Ground connector Pin C2044 , Circuit 776 (O/BK). Then, turn ignition switch to RUN. Blower motor should not operate.
Does the blower motor operate?
Yes
GO to H2
No
REPLACE remote climate control module.
H2 CHECK BLOWER SPEED CONTROLLER
Turn ignition switch OFF. Reconnect harness connector C2044 to remote climate control module.
Disconnect Circuit 776 (O/BK) from A/C blower motor speed control connector Pin C2043 and reconnect connector to A/C blower motor speed control. Then, jump Pin C2043 , Circuit 57 (BK) (ground) to Pin C2043 of A/C blower motor speed control. Turn ignition switch to RUN. Blower motor should not operate.
Does blower motor operate?
Yes
REPLACE A/C blower motor speed control.
No
SERVICE Circuit 776 (O/BK) for open.
