The A/C in my 2006 VW Passat does not work consistently. It works at times before the engine gets to operating temperature, but quits upon reaching normal operating temp. Any ideas?

the wire inside the bulb socket could be rusted and broken. wire connection broken before it reach the bulb. socket mostly burn up or dirty, missing a seat. replace socket and test the socket wire connection. wrong bulb also

This is such an old thread but if you or come one else has stumbled back upon this thread:
When you pull the fuse panel cover off of the drivers side and you see the fuse panel, if you look directly above that panel mount you will see a small-ish hole that goes to the internals of the dash. When you get a flashlight and look in there you will see a relay panel and the closest one to you will be the 384 relay. Most are numbered on a VW/ German Engineered autos but if not that is where it'll be.

vw uses a module to control the fan if the controller goes bad the fans shut off the pricey part is both fan motors and the module come a set from the dealer

First of all you need to programm all ignition keys using suitable diagnostic equipment (VAS, VAG-Com) connected to the data link connector of the car.

You have an electronic immobilizer key recognition problem. Now your key chip is not recognized by the transponder antenna fitted on the ignition switch barrel.



This warning lamp indicates that the engine is locked by the immobilizer system, and the engine start sequence must be repeat again.

From year 1995 in Audi-VW (VAG) cars is used engine immobilizer. The VAG group immobilizer system consists of an immobilizer ECU which controls the recognition of keys and the Engine Management ECU system. Immobilizer is activated when the ignition key is removed and, together with the engine control unit, largely prevents unauthorized starting of the engine. The system uses a transmitter and receiver unit in the ignition key (transponder). Whenever an attempt is made to start the engine, it transmits a new code to the car's electronics. The immobilizing is only cancelled and car motor electronic receives permission to start engine if the key sends a right authorization code.

Change ECT/engine coolant temperature/sensor.This job can be done only by a professional mechanic.

Heed of antifreeze coolant temperature!!!
First time you might check the thermostat operating.
The thermostat location for VW Passat 4Motion 1.9 TDI - AJM engine, is on back of the alternator at the bottom side of the bracket.
IMPORTANT: It is NOT necessary to replace the alternator if you want to change the thermostat !!!
Thermostat checking:
1. Cold engine. Start up the engine and watch of the water temp indicator. After first value 60 Celsius Degree you still warm up the engine until the lifter (pointer) reach 80 C deg. (second mark after 60 C deg.). At this time you let engine running at idle speed and check with your hand the thermostat plastic housing and hose temperature in bottom left side of the engine. Heed of alternator driving belt and ventilator fan !!!
2. If the thermostat is good the hose must be cold until the water temp indicator reach almost 90 C deg.
3. The thermostat opening temperature is 87 C deg.
4. If the hose is already warm the thermostat is out of order.

Thermostat location, Part number: 044121113, in german - "Kuehlregle" (Price around $25):


Important note: Always replace the thermostat seal, position 7 in the above picture.

Please do rate my response. Thanks!

The A/C in my 2006 Passat 2.0 T is not working consistently. It seems to quit giving cold air when the outside temp is the hottest. It sometimes works fine until the engine is warmed up-then starts blowing hot air. Any Ideas?

p3081 is the error code for the engine not reaching correct operating temperature. It could be an issue with the thermostat or the ECT (coolant temperature sensor) valve.

As far as how to repair those items, your best bet is to purchase a repair manual. It will save a lot of time and frustration.
Good luck hope this helps.

5w20

assuming fuse and relay are good..no fan should be running when the engine is cool/cold, the only time the fan should be running when it reach over operation temperature which then the fan kick on to bring the temperature back down to it operation temperature. both fan work in sync with one another, addition cooling is needed when the ac is running. when the last time have you replace thermostat and Thermos sensor/switch. I would replace both unit if you have not done so. The thermos/switch will turn the fan on when it reach certain temperature and cut off when it sense the temperature drop in the engine.