93 Chrysler Town Country Mini Van's heater dosn't

We have a 93 Town & Country Mini Van. A few months ago the heater/air conditioner fan stopped working. At the local high school there is a auto shop who said they could install a new heater fan for the experience of the students. I purchased a new fan and took it in to the school & they installed the fan. Since then the heater hasn't put out hot air only mildly warm air. It makes no difference what position the temperature setting is at the air is only mildly warm, and since it's winter I would like it to be hot air. The high school shop said it's nothing they did. What could the cause this and how can it be fixed.
Thank You
Roger
You may have air in the cooling system, low coolant, faulty heater control valve, faulty blend door or cabling, bad thermostat, or a restricted heater core. Can you give us a little more info please?

Steve
Prior to the problem with the heater fan the air conditioner and heater was working fine, the engine temp. and water level was good. Since the new heater fan was installed nothing else has been changed and the engine temp. is running at it's normal range. I did try to turn on the rear heater/ air and cold air came out of the vents not even the warm air that was coming out of the front vents.
Is this of any help?
Roger
Roger, the next step is to let the engine get to normal operating temperature. Carefully grab the heater hoses one at a time. If they are both hot the problem is in the ducting of the heater module. If one is hot and one is cold, you have a restricted heater core.
2 of the biggest problems I have seen with these vehicles heat is the heater control valves get stuck in the off position and the blend air duct binds up. Check these out and repost with what you find.