A/C Not blowing cold

[jpeff31787]

my company vehicle is an 03 suburban and it does the same thing. Sucker won't cool off at all if its just idling. I went start it 15 minutes before leaving the other day, and the thing was just as hot as it when i first started it. It doesn't start blowing cold until I start moving. Brought it to the mechanic, he said its just old... I call BS, well either BS or my boss didn't want to pay for it to get fixed and he thought it was easier to just tell me that...