Thanks for the info stevebfl and ChinaClipper. I started troubleshooting this weekend and the weirdest thing happened. While in a/c mode and the air blowing cold through the center vents and hot through the exterior vent, I rolled the temp control to max heat. I let the system operate approximately 30 seconds and the rolled the wheel back to min. The air then blew cold out of all vents. This procedure has been working for the past few days but I would still like to correct the problem.
stevebfl - Is there anything that can be eliminated from the previous troubleshooting information?
ChinaClipper - Did you experience the same quirk?