My Heater mode selector switch will not switch the heat from defrost to floor or cabin. Any thoughts on how to rectify this problem would be appreciated.
Thanks,
Al

 

Defrost is the default mode when there is little or no vacuum to any of the various HVAC servos. So, if it is stuck in defrost, you likely have a vacuum leak. Look under the hood on the passenger side for disconnected/melted hoses. Check the vacuum reservoir. Look up under the dash for disconnected vacuum lines.

 

Thank you. I'll try your suggestions.