Heater fan only blows on high seaberng 2002 - 2001 Chrysler Sebring

A few possibilities. Easiest (cheapest) to worst (expensive).
1) fuse blown
2) bad fan switch
3) your blower fan has gone to fan heaven (blower fan died)
Go to parts store and get a Chiltons/Haynes repairs manual for your make,model, and year. It has pictures and diagrams for replacement of switches etc. As well as a trouble shooting guide that may offer suggetions not covered in my answer.

When the fan motor is loud it means its out of balance. Kind of like a dishwasher.

Could a business card or two have slipped through the defrost vents ? or maybe leaves have accumulated in the fans squirrel cage.

A heater motor isn't hard to remove. Usually above your feet on the passenger side held in with 3 or 4 screws and one heavy wire.

Heater core may be clogged. Try flushing it to see if water flows through freely. Also check the heater water control valve for restrictions.

I would need more info to give any advice.
I assume you mean the blower for the ac and heater.
How is it not working but works on high ?
And what power are you turning off that makes it blow harder ?

if the fan does not increase speed as turned up replace resistor assembly usually in heater housing under dash.if doesn,t nave separate resistor assy.it is the fan switch

The resistor card may be defective. Does it blow any speed? If it only works on high speed it's probably the resistor card. If the fan is intermittent, it may be either the fan switch or the blower fan.

Sounds like your heater blower motor is not functioning properly. At high speeds it's probably drawing air in from the outside then through the vents (defrost, etc.). If blower motor sounds like it's running, then maybe the squirrel cage (heater fan blade) is not spinning and in need of repair or replacement.

bad gauge or bad thermostat.

Fans come on because when you disconnect, it goes to default mode of fans on high speed.

could be the heater/ac controller head. This is the buttons and switches that you use or you have a bad heater blower. Check fuses and then the wire to the heater blower motor under the hood on the passenger side. Hope this helps

replace heater control switches