Hello I have a 2003 Dodge Durango. A few months ago I had the A/C serviced at a shop and was working great. But now when am stopped at a light or leave the vehicle running while parked it starts blowing hot air. Once I start driving again the A/C starts to cool.

 

Welcome to DF
I will move your post to the tech section. You will get more response from the other members.

 

Sounds like an issue with not getting enough airflow through the condenser. Check to make sure that the electric fan is coming on when the a/c is on.

 

+1 on the efan not coming on as it should

 

Also, you may want to take it to a car wash and use the high pressure water gun to blow out and clean out your a/c condenser and possibly radiator to allow more air flow if the E-Fan is working.

If Efan and power washing your condensor does not resolve the issue. Check the fan clutch. Could have gone bad.