heating system

The first step would be to check for proper coolant flow through the heater core. With the the engine warm touch both heater hoses, both should be warm. If only the inlet hose is warm then there is a coolant flow issue - possibly a plugged heater core. If both heater hosed are warm coolant flow is OK and the problem is with the heater control inside the car. Find the cable from the heater control on the dash to the temperature door in the heater box and make sure the temperature door is moving when you adjust the temperature on the dash.

give the man (the "Oakman") a cigar, or at least a five star rating. crud in the coolant can be from lack of service, addatives that are detrimental or using incompatable coolants. mixing green and pink coolant can cause cooling system clogging.