We had a 2000 Intrigue, and had hot air coming out of the register at the passengers feet. Drove my DW nuts. When we got our 2001, had CC put a valve in the bay, and a hose that intersects the return at the hot water heater, so in effect cuts off the loop that goes up to the refer exchanger, then on to the passenger, then the plumbing bay. End of hot air. Don't know if the Magna has the same loop, but you should be able to see the routing in your schematics book. I just switch the valve depending on the season.
Tom and Linda
2001 CC Intrigue 40' Suite of Dreams