my heater blows warm air then cold air,it keeps alternating when i have the heat on
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2000 Mercury Mountaineer Question: heater goofed up
DaveJHM November 21, 2010, 01:39Master
You could have an issue with your automatic temperature control if it is so equipped. A temperature sensor could be at fault, or a temperature blend door issue could be present (but not likely for this concern...). Lastly, you could have a thermostat issue - sticking open intermittnetly.
Answer #2Visitor, January 23, 2011, 17:17
Answer #3Visitor, January 23, 2011, 18:11
it also has airconditioner is alternating when turned on ,sometimes blows cold air sometimes regular air,put new thermastat in and had all fluids changed,oil and coolant and transmission fluid it heater and air conditioner still changes air.heater will work for while then blows cold.air conditioer blows cold then without touching any of the controls it blows hot air.
ReplyDaveJHM, January 24, 2011, 00:12Master
Please refer to the original answer; could have a temperature blend door actuator failure. A proper diagnosis is in order.