Sounds like vents are in open position where it passes through based on speed with or without fan on
yes
This may be a vacuum problem not an electrical problem. Determine if you hear the fan running? When you accelerate the engine vacuum is reduced and the heater/ AC door diverts to floor instead of upper vents.
I have the same problem, and looking for answers. Please help!
Your AC might be blowing out of dash vents on the windscreen as you might have turned the knob to that particular mode. It is also possible that the vent mechanism might be out of order or broken.
The heater core is leaking coolant.
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If central air conditioner turns on but is not blowing through the vents, check the filter. If it is dirty, change it. Change the thermostat into cool, this will defrost the air conditioner.
Pin cone
If the air vents of the Chevy trailblazer 2004 are not blowing air, have the fuel pump checked.
you may just be low on freon
your cabin filter might be dirty
When there is a problem in the vent system it defaults to defrost setting. Check the doors & vac supply