Heater valve busted?

[jlevie]

I don't see the blower as having an affect on the flow of coolant through the core, but I can see how it might have an affect on the ducts or, if clogged, the flow of air through the heater core. Those are where I think you need to be looking.

Similar case sort of:

I get heat while driving, but once i come to a stop or idle the heat drops to cold.

A plugged heater hose/valve, or air in the cooling system are the usual cause of this.