1978 Mercury Monarch heater went out, what is the problem?

[i_8_my_girlfriend]

I live in Washington and it is cold. The heat in my 1978 Mercury Monarch worked in the past it just mad a funny squealing noise, yet the car warmed up just fine, defrost and all. A couple days ago I was driving with the heat on full blast, and the heat was making the normal squealing noise then all of a sudden it just stopped working. No heat, no defrost, nothing. What could be the problem, and what could be the fixing cost if i can't do the job on my own? Thanks! (The car has an inline six) Also if it is the heater motor, where is it located on my car?

 

[Don K]

As a mechanic for many years I can tell you that it's most likely the thermostat. It sounds like it it not opening up to allow the water to circulate in to the heater core. I noticed someone saying that it could be the heater core. Well usually if the heater core is bad it would leak. Do you see any water or antifreeze in side the vehicle? do you smell antifreeze? are you loosing any water out of the radiator? If not then it is most likely the thermostat. You can purchase one for under 10 bucks. it should only take about 15 min. to change it. I would also purchase a new thermostat housing gasket. good luck.