2003 vw passat air cond blows warm air

The only other thing then would be if the compressor is turning, engaging, and the cooling fan working properly. You should either be able to see the compressor clutch engage, as the switch is energized, or at least hear it click loudly when the switch is energized. If it is not, then there are sensors for the low pressure/high pressure line to tell the compressor when to function, that also have to be checked.

As the engine runs with the compressor turning, one line should be hot/warm, the othe,r (larger diameter hose) should be cool/cold, if the system is working properly.

If the compressor is turning when you have the A/C turned on, then see if the cooling fan is running as well. It must run to remove the heat and cause the process to function properly.

Good luck!

Sounds to me like it's your thermostat... The reason it works okay when you're moving, is because the air is cooling the radiator...

Check the coolant level, - air in cooling system.

possibly gas pressure to low or pressure switch on aircon condensor faulty.

good day, you may have some heating core issues, anti freeze leakage, have it checked. hope this helps, have a nice day

If there was a blockage,the low pressure pipe would freeze up after awhile.Check that there is sufficient gas in the system and there are no leaks.The high pressure should be between 8-13 bar and low pressure shouldbe between 1.8-3 bar.

It's very possible that the fan itself is bad - relatively common on VW's. First check the fuse for the fan on the fuse panel.
You could also have a fan control module problem. Can you hear/feel the compressor turn on? If so, then the module is good and you probably have a bad fan or a blown fuse.

There is an electrical relay that is malfuctioning. I had the same problem on my 2000 VW Passat. I just got it fixed, part cost 48 dollars and labor will be about an hour.

AC's have a low freon switch that shuts off the system to protect the compressor in the advent that you have a freon leak have the system checked for a leak

you check the fan motor and the compressor winding and terminal you have a short