Possible Causes
WARNING: This page is about a different car, the 2005 Jeep Liberty. However, it is still accessible from the selected car via links, so may be relevant.
FUSED B+ CIRCUIT OPEN
CABIN HEATER RELAY OUTPUT CIRCUIT SHORTED TO VOLTAGE
CABIN HEATER RELAY OUTPUT CIRCUIT SHORTED TO GROUND
CABIN HEATER RELAY OUTPUT CIRCUIT OPEN
CABIN HEATER RELAY