Temperature Control Inaccurate

SYMPTOM DESCRIPTION:

The selected temperature can not be attained or maintained. Check the following:

CAUSE/REMEDY:

^ TCC CONTROL UNIT OR SENSOR INPUTS DEFECTIVE. Be sure to check the basics, [1][2]Initial Inspection and Diagnostic Overview Perform On-board diagnostic test and system tests.
^ POOR CONTACT AT CONTROL UNIT, FEEDBACK POTENTIOMETER OR SENSOR CONNECTIONS. Repair harness connections as necessary.
^ FEEDBACK POTENTIOMETER OUT OF ADJUSTMENT. Refer to ADJUSTMENT PROCEDURES.
^ LEAK AT BLEND AIR FLAP VACUUM ELEMENT OR SYSTEM.
^ SWITCHOVER VALVES DEFECTIVE.
^ HEATING SYSTEM OUTPUT LOW.
^ A/C SYSTEM OUTPUT LOW.