A/C wont cool at idle

Hello, I have a Ford F-150 that will not cool at idle speed, puts out somewhat warm air. Once moving it will get cold. Checked with gauges and it has correct fill. Only a problem at idle speed. Could this be a fan clutch problem? Referring to the A/C not cooling at idle. When I start the truck, it blows warm air. It continues to blow warm air until I get the truck moving. I have waited a long time just to see if it would start cooling, but it doesn't. Once the truck is moving, it starts blowing cold air. Cools great as long as i'm moving. If while parked, I can take the selector off of "max cool" and move it to a lower setting and it starts to cool. This removes the cabin air re circulation. What's going on with this?