Symptom Chart - Climate Control Systems

WARNING: This page is about a different car, the 2018 Lincoln MKT. However, it is still accessible from the selected car via links, so may be relevant.

Condition	Possible Sources	Action
NOTE: Some PCM DTCs may inhibit A/C operation. If any PCM DTCs are retrieved, diagnose those first. Refer to the ENGINE CONTROLS - INTRODUCTION (EXCEPT DIESEL & HYBRID) .
No communication with the HVAC control module	Fuse Wiring, terminals or connectors Communication network HVAC control module	REFER to Module Communications Network .
No communication with the RHVAC module	Fuse Wiring, terminals or connectors Communication network RHVAC module	REFER to Module Communications Network .
Externally Controlled Variable Displacement Compressor (EVDC) poor performance/does not operate correctly	Refer to the Pinpoint Test	GO to Pinpoint Test Y .
Unable to duplicate the customer concern and no DTCs present	Refer to the Pinpoint Test	GO to Pinpoint Test H .
The HVAC functions are inoperative/do not operate correctly from touchscreen only	Communication network FCDIM	REFER to Information and Entertainment Systems Touchscreen or Information and Entertainment Systems THX Symptom Chart and DIAGNOSE the touchscreen.
The air inlet door is inoperative	Refer to the Pinpoint Test	GO to Pinpoint Test I .
Incorrect/erratic direction of airflow from outlets	Refer to the Pinpoint Test	GO to Pinpoint Test J .
Reduced outlet airflow	Refer to the Pinpoint Test	If the A/C compressor does not cycle, GO to Pinpoint Test M . If the A/C compressor cycles normally, GO to Pinpoint Test R .
Insufficient, erratic or no heat	Refer to the Pinpoint Test	GO to Pinpoint Test K .
The A/C operation is erratic. The discharge air warms up when the vehicle comes to a stop.	Refer to the Pinpoint Test	DIAGNOSE all PCM DTCs before proceeding. REFER to the PCM DTC Chart . If no PCM DTCs are present GO to Pinpoint Test X .
The A/C is inoperative	Refer to the Pinpoint Test	GO to Pinpoint Test L .
The A/C is always on - A/C compressor does not cycle	Refer to the Pinpoint Test	GO to Pinpoint Test M .
The A/C is always on - A/C mode always commanded ON	Refer to the Pinpoint Test	GO to Pinpoint Test N .
Temperature control is inoperative/does not operate correctly	Refer to the Pinpoint Test	For driver side temperature concern, GO to Pinpoint Test O . For passenger side temperature concern, GO to Pinpoint Test P .
The blower motor is inoperative	Refer to the Pinpoint Test	GO to Pinpoint Test Q .
The blower motor does not operate correctly	Refer to the Pinpoint Test	GO to Pinpoint Test R .
The auxiliary blower motor is inoperative	Refer to the Pinpoint Test	GO to Pinpoint Test S .
The auxiliary blower motor does not operate correctly	Refer to the Pinpoint Test	If the auxiliary blower motor does not operate correctly from both the front and rear auxiliary controls, GO to Pinpoint Test T . If the auxiliary blower motor does not operate correctly from the rear auxiliary controls only, GO to Pinpoint Test W . If the auxiliary blower motor does not operate correctly from the front auxiliary controls only, CHECK for HVAC control module DTCs. If HVAC DTCs are present, GO to the HVAC Module DTC Chart . If no HVAC DTCs are present, INSTALL a new HVAC control module. REFER to Climate Control .
The auxiliary temperature control is inoperative/does not operate correctly using the front/rear auxiliary climate controls	Refer to the Pinpoint Test	If the auxiliary temperature control is inoperative/does not operate correctly from both the front and rear auxiliary controls, GO to Pinpoint Test U . If the auxiliary temperature control is inoperative/does not operate correctly from the rear auxiliary controls only, GO to Pinpoint Test W . If the auxiliary temperature control is inoperative/does not operate correctly from the front auxiliary controls only, CHECK for HVAC control module DTCs. If HVAC DTCs are present, GO to the HVAC Module DTC Chart . If no HVAC DTCs are present, INSTALL a new HVAC control module. REFER to Climate Control .
The auxiliary panel/floor control is inoperative/does not operate correctly using the front/rear auxiliary climate controls	Refer to the Pinpoint Test	If the auxiliary panel/floor control is inoperative/does not operate correctly from both the front and rear auxiliary controls, GO to Pinpoint Test V . If the auxiliary panel/floor mode control is inoperative/does not operate correctly from the rear auxiliary controls only, GO to Pinpoint Test W . If the auxiliary panel/floor mode control is inoperative/does not operate correctly from the front auxiliary controls only, CHECK for HVAC control module DTCs. If HVAC DTCs are present, GO to the HVAC Module DTC Chart . If no HVAC DTCs are present, INSTALL a new HVAC control module. REFER to Climate Control .
The auxiliary temperature, panel/floor mode or blower motor controls are inoperative/do not operate correctly using the rear auxiliary climate controls only	Refer to the Pinpoint Test	GO to Pinpoint Test W .
A/C pressure relief valve discharging	High system pressure A/C pressure relief valve	CHECK the high side system pressure. If the pressure is below the A/C pressure relief valve open pressure, INSTALL a new A/C compressor. REFER to Climate Control . If the system pressure is above the A/C pressure relief valve open pressure, REPAIR the system for a restriction.