Truck Repair: truck overheating, calcium buildup, falure

Question
mike i just bought a 1994 chevy s-10 pick-up and the only thing wrong is that heat won't blow out of the vent and since heat isn't coming out my engine heats up.i don't want it to overheat.what could be the problem.the previous owner said he had it fixed once but it broke again.what could it be.

Answer
Your engine in NO WAY should overheat due to the heat not coming out in the cab.  If your engine is overheating there is a falure in the cooling system itself (water pump, pluged radiator, thermostat, ect)

I would drain a little coolant out of the radiator and look at the inside to see if the tubes are clogged (looks like calcium buildup).
Look at the waterpump.  There is a weep hole on the lower side of the pump.  Look and see if there are signs of coolant weeping out; if so it is bad.
Wash the radiator out real good with a garden hose.
Repair the overheating prob first, then go for the heat in the cab.