Avoid a trip to the mechanic by trying to troubleshoot problems yourself in your GMC Sierra. Air conditioning problems are quite common, but can often be quite simple to diagnose and even fix. Take a few easy steps to try and determine the cause of the air conditioning problems.
Start the engine and let it to run for a few minutes to allow the air to cool. Double check the controls to make sure the correct buttons are selected. This may seem simplistic, but human error could be to blame.
Adjust the climate controls. If they are working correctly with the right amount of resistance and stopping at the right places but have no effect on the air then it is probably a simple fuse problem. If they are not working correctly then it is probably a control panel issue.
Get to the fuse box to change the blown fuse in a GMC Sierra by opening the driver's side door and prying off the trim panel to the left of the steering wheel. The fuse can be removed with your fingers. If the Sierra was purchased new there should be replacement fuses in the fuse box.
Check the control panel next in your GMC Sierra. Remove the trim plate bezel surrounding the center instrument panel. Pull of the storage tray and the accessory switch.
Unscrew the four screws holding the climate control assembly in place, push in the retaining tabs and pull the control panel out. Unplug the electrical connector. Sierra models older than 2001 have no retaining tabs or accessory switch.
Listen for the blower motor while the engine is running and the air is on. There are two different possible blower motors in a GMC Sierra. Both are easily accessed from under the hood. The Delphi will sit vertically, while the Visteon sits horizontally. In both cases, remove the sound insulation panel, unplug the electrical connector and unscrew the three screws holding the blower motor into place.
