Output Diagnostic Test Mode

WARNING: This page is about a different car, the 2001 Volkswagen EuroVan, 2000 Volkswagen EuroVan, 1999 Volkswagen EuroVan, and 1997 Volkswagen EuroVan. However, it is still accessible from the selected car via links, so may be relevant.

NOTE: Flap motors will be activated in sequence and over their complete operating range. First half of the test, motor will be continuously activated and remainder will be driven in stages. After test flap will move to position selected by A/C control panel. If no DTCs exist after test, but flap did not move through its complete range of motion, check for mechanical damage. If no DTCs exist, but A/C compressor does not engage, check wiring and connectors from A/C pressure switch and A/C clutch.

Ensure ignition is off. For best results, ensure A/C-heater control head is reading ambient temperature of at least 54°F (12°C).
Connect Scan Tool (VAG 1551) to Data Link Connector (DLC) located under left side of instrument panel. Input address word 08, AC/HEATING ELECTRONICS. Press right arrow button until SELECT FUNCTION XX appears in display. Press buttons "0" and "3" to select OUTPUT DIAGNOSTIC TEST MODE (DTM) function. Press "Q" button to confirm input.
Scan tool will check following components in sequence: A/C-heater control head, temperature regulator flap motor, central air flap motor, footwell/defrost flap motor, electrical circuit to fresh air blower, auxiliary evaporator blower, auxiliary warm air fan and A/C clutch circuit. After about 30 seconds, all checks should be completed.
If display reads FUNCTION IS NOT RECOGNIZED OR CANNOT BE CARRIED OUT AT THE MOMENT, output diagnostic test mode is concluded. Press right arrow button. Check A/C-heater control head display. If all display segments appear, control panel is okay. If all display segments do not appear, replace A/C-heater control head. After completing output diagnostic test mode, check for any Diagnostic Trouble Codes (DTC).