Can anyone help I noticed that i have heat from my defrost setting but nothing else cool air comes out the vents i flushed the system and put new cap on the radiator any ideas what could be causing it.

 

You probably have a vacuum leak. The vacuum leak isnt allowing enough vacuum to goto the actuator that opens the door for the different control settings. Alot of times its the vacuum line that goes to the vacuum ball which is located on the drivers side toward the firewall or mounted to the underside of the hood. thats where id start......

 

Could also be a bad vacuum switch at the transfer case. The switch is located on the drivers side of the transfer case, it is known to fail (leak) and suck up fluid fromt the transfer case into the A/C-Heater controls. GM has a service bulletin for this and a new switch design. The fluid in the control lines acts like a no vacuum situation but with out the "leak" which would make for a rough idle but as soon as you accelerate the roughness goes away...