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Why would the AC and heater blow air through the defroster or the floor vents but not through the dashboard vents?


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2015-07-17 17:38:39
2015-07-17 17:38:39

Because there is a vaccume leak @ the reservoir or the hoses going 2 the reservoir There is a small,main vaccume hose from the intake manifold that supplies VAC 2 the AC system.The hose is usally 1/8 0r 3/16 in size.Older fords have a tank that looks like a fruit juice can for a reservoir.U have 2 have Engine VAC @ the AC Controls 2 work.If a hose or line is Cracked,the AC will usally blow out the dash only when not under acceleration.when u ACC the air will go 2 the floor.There could even B a hose off under the Dashboard. Some cars or trucks have small rubber hoses or small plastic hoses with rubber conections going 2 the intake manifold.

Glenda, most systems use either mechanical or vacume to operate the vent doors on the airflow ducts. You either have a vacume leak or the mechanical lever needs adjustment. . John In Montana


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It should blow through the floor vents. Modern vehicles generally use movable baffles in there HVAC systems, to direct air flow where the controls indicate. If the controls allow airflow to the floor, but nothing flows out, there is a malfunction between the control switch and the actuator that directs the flow.

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You have a leaking heater core. You might smell antifreeze if you turn on the defroster.

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If the heater has a sweet smell it could be that the heater core is leaking engine coolant. When the leak gets worse you will have a wet floor on the passenger side and the windshield will fog up when you turn on the defroster.

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You didn't mention what vehicle you have but in most vehicles the heater core is located under the dash on the passenger side. The heater core is known to spring a leak and show up on the passengers floor. Turn on the defroster and see if your nose senses the sweet smell of radiator coolant. The inside of the windshield my fog up when the defroster is turned on, this would also indicate a leaky heater core.

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