Heater and Windshield Wiper conflict

[DrG]

I have a mildly bothersome problem with my 2005 H2. When is cold and wet, and I am running the heater and the wipers on intermitent, the heater blower cuts out for about a half a second when the wipers run a cycle. It's not every cycle but varies. The heater may cut out on every cycle then run normally for 3 to 4 cycles and cuts out again. I can't find any kind of pattern to it. I have been able to demostrate this to a hummer mechanic at the dealership who has no explaination. He has done some work looking for a problem but can't determine the cause. There is no effect on the air conditioner in the summer. It seems to be temperature related. Any ideas what the connection is between the heater blower circuit and the wiper circuit?
Happy New Year everyone.
David