Air conditioning runs cool when driving but hot air comes out when waiting at a light or idling

What is your question?

For the past two swimmer seasons, the air conditioning will blow cold air (blows nicely) when in gear and in motion. When I'm at a light or idling while in line say at a bank or restaurant, it still blows air, but warm air.

How long has your 2007 Isuzu Ascender had this problem?

2 summers but has gotten worse