1986 Mercury Sable heater not working

[quote:2125f362c7="Krista Karlsson"]Heater problem
1986 Mercury Sable Front Wheel Drive Automatic 87,850 miles
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The interior heat has gradually stopped working. I found that if I had the heat turned to off when I started the car, and then turned it to defrost after it was warm I would get a little heat. Now it does not mater what I do there is no heat.

My question: How do I determine what is wrong? Or do I just replace a part, and if so, what do I replace.

Thank you—Cold in Seattle[/quote:2125f362c7]


check your coolant level and adjust if needed
check the thermostat
and if all good you need the heater core flushed

Thank you so much for taking the time to answer my question. I will let you know my results after following your advice.--Krista