I have a similar problem with my 2005 SRT-6 blower motor (Both AC and heater mode). Fan and compressor come on normally and after 5 or 6 minutes the fan stops (at any fan speed). It will eventually come on normally by itself. If I take it our of recirculation mode the forced air will be cold albeit at a low volume.
It is one of those intermittent problems that are hard to diagnose. Apppreciate any suggestions.