Pinpoint Test M: HVAC Functions Verification
WARNING: This page is about a different car, the 2010 Lincoln Town Car. However, it is still accessible from the selected car via links, so may be relevant.
NOTE:
Diagnose any HVAC module DTCs before carrying out the following pinpoint test.
NOTE:
Some PCM DTCs may inhibit A/C operation. If any PCM DTCs are retrieved, diagnose those first. Refer to PCM DIAGNOSTIC TROUBLE CODE INDEX
- M1 CHECK THE BLOWER MOTOR OPERATION
- Key in ON position.
- Select PANEL mode.
- Observe blower motor operation and select each blower motor speed.
- Does the blower motor operate in all selections and change speed in each?
- YES : Go to M2.
- NO
: If the blower motor does not operate in any setting, go to Pinpoint Test R .
If the blower motor does not properly change speeds or shut OFF, go to Pinpoint Test S .
- M2 CHECK AIRFLOW OPERATION
- Select the highest blower motor setting.
- While observing the airflow, select each of the airflow positions (PANEL, PANEL/FLOOR, FLOOR, FLOOR/DEFROST, DEFROST).
- Is the airflow directed to the proper outlets?
NOTE: Refer to DESCRIPTION AND OPERATION for proper airflow descriptions.- YES : Go to M3.
- NO : Go to Pinpoint Test L .
- M3 VERIFY TEMPERATURE CONTROL OPERATION
- Start the vehicle and allow it to reach normal operating temperature.
- With the A/C OFF, select PANEL mode.
- Change the temperature setting from the coldest to the warmest and back to the coldest.
- Does the temperature change between very warm to cool?
- YES : Go to M4.
- NO
: If the temperature does not get very warm, go to Pinpoint Test N .
If the temperature does not change at all, go to Pinpoint Test C .
- M4 VERIFY THE A/C CLUTCH DOES NOT ENGAGE WITH A/C OFF
- With the A/C OFF, select PANEL mode.
- Select the coldest temperature setting.
- Is the outlet temperature close to ambient temperature?
- YES : Go to M5.
- NO
: If the temperature is warmer than ambient temperature, INSPECT for binding or broken linkage. If no condition is found, INSTALL a new blend door actuator. TEST the system for normal operation.
If the outlet temperature is significantly colder than ambient temperature and the A/C compressor clutch cycles normally, go to Pinpoint Test Q .
If the outlet temperature is significantly colder than ambient temperature and the A/C compressor clutch does not cycle, go to Pinpoint Test P .
- M5 VERIFY A/C CLUTCH ENGAGEMENT IN THE A/C MODE
- Make sure the ambient air temperature is above 2°C (35°F).
- Select PANEL mode.
- Press the A/C button (indicator ON).
- Does the A/C clutch engage when the PANEL and A/C button (indicator ON) is pressed?
- YES : Go to M6.
- NO : Go to Pinpoint Test O .
- M6 CHECK THE RECIRC OPERATION
- Press the RECIRC button (indicator OFF).
- Select PANEL mode.
- Select the highest blower motor setting.
- Observe airflow noise.
- Press the RECIRC button (indicator ON).
- Does the airflow noise increase when the RECIRC mode is selected (indicator ON)?
- YES : The system is operating normally.
- NO : Go to Pinpoint Test K .