1996 Mercury Sable Has No Heat From Vents

1996 Mercury Sable. Engine Size : 3.0

Question: My cars heater is not working. The temperature will fluctuate constantly from 3/5ths of the way up to 1/4 the way down back and forth constantly.

I have changed the thermostat in this car. There is no leaking water anywhere either. I have burped the entire system as well but with no luck. Please any advice I got $400 to fix it.

Answer: Fluctuating engine coolant temperature is a normal condition of a functioning thermostat. If it is very cold where you are this sounds about normal. You should at least be getting heat when the temp is at its highest. If you do get heat when it is at the highest, but then none when it drops, then this would be a coolant temp issue. If no heat at all, then this is not a problem of the coolant not heating up, but another problem. Your Mercury could have a problem in the temperature door in the dash not directing heat over the heater core, or even a plugged heater core.

Put the HVAC fan on high, ear up to a vent and switch from cold to hot- you should hear a change in the airflow in one of the vents. If not, it is an issue with the temperature control of the dash. If you do, then suggest getting the heater core back-flushed.


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  • Guest - Peggy

    Hello. I had my car towed home from the library. It wouldn't start. The battery is fine. I was told that it was a head gasket problem. What is the function of the head gasket? I have a 1999 mercury sable. I have also been told that my six cylinder car is runner on five cylinders due to water leaking on a spark plug. I was told to keep putting water in the car. Why is this? What is the function of the head gasket when it comes to starting the car? I know I might sound stupid - I would just like to know what is going on! I am told that a head gasket cost between! $1,000 to $1200 to repair my car. Can you please help me to understand what is going on? When I try to start the car, it acts like it wants to start...? Help.