I have an 1985 elky, somtimes when i turn the defrost on, and the heat all the way up it won't blow hot air unless you pull it back to cold and then back to hot about 5 or 6 times. Also, when the fan is on high(no matter hot or cold) the fan seems real weak, i think my girlfriend blows more hot air then this thing. Any suggestions?

I would first check your fan switch for loose/burned connections.

Also make sure the vacuum line to the heater control valve is not cracked or real hard. The heat problem could be problems getting the valve to open.

The heater control valve is normally "Open" the only time vacuum is applied to the valve is when the temperature switch is in the full cold position, thus closing the flow of coolant through the valve.