Sorry bad news Your heater core has a leak
thats because your blower went out
There may be something blocking the deflectors from sending air up there.
If it blows only out the defroster vents : then check for Vaccume leak Rick ASE L-1 Master TransMichigan.com
My ac blows only in the defroster and not any of the other vents i have 98 ford windstar 3.8 v6
Low coolant level? Thermostat opening too soon? Plugged or restricted heater core? Water pump not circulating coolant? System airbound?
I think your refering to the door in the heater housing that directs air to vents, floor or defroster vents, there is also a blend actuator that mixes heated or cooled air to give the correct temperature from the selector.
Defroster actuator lost vacuume[manual control] or locked up[electronic ATC]....
Either you need to pen your vents or there is some vent obstruction.
a 5 cent broken hose that goes from engine through the firewall
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.
the middle vents only supply air from the ac unit using a separate in dash fan. the floor and defrost vents come only from the heater
your switch cable might be broke you will have to remove your dash
It sounds like there is a vacuum leak. Check under the dash for any small hoses not attached and then look under the hood for any. The hoses should be small and grey or black.
The Heating/ ventilation systems in cars are large structures throughout the dash board, that have many channels of which air can flow through. When you use your face vents, the air is blowing from the upper vent channels. If you use the windshield defroster, the air comes from the very same upper channels, the channels just switch. They have a divider that blocks airflow one way or another. Very much like train tracks, when you change the settings with the switches, the airflow changes because the divider has moved. Therefore you cannot use both at once. The only reason why you can use the foot vents, and face vents at the same time, is because they have a divider that splits the channel that they share, you can use face vents (full force), foot vents (full force) or both split (half force). The Defroster is made to work fast, so if you use the face, and defroster vents at the same time, the defroster would be half as effective. This is why you cant use them both at the same time.
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Most temp blend doors have an electric actuator. The defroster, dash vents and floor vents are usually run by vacuum.
some thing is probley cloging the vents take it appart and ckeck.
Dont know what the problem is but i can tell you its a vacuum leak . the vents are vacuum operated and require air pressure to change between the vents and floor. the defroster is default setting you may have a vacuum line that has come undone but all i know is its somewhere under the dash.
I am sorry, I am not technical on this stuff, but we had the same problem on our 95 Mustang GT. We had to take it into the dealer and the problem was that one of the hoses had come loose, so it was not blowing enough air pressure to force the vents open.
Its your Heater core if it smells like a syrupy sweet smell if not then its your thermostat
If air blows from defroster only, the vacuum line to the blend door may be broken. You can access most of it under the hood.
This means that you have either an issue with a vacuum line or one of the a/c - heater doors behind the dash is not working correctly and you need to start off at the a/c - heater controller to check that all positions are working...........
heater core is shot and you have to get a new one