The compressor working to remove the heat from the air, but the blades could be dirty
if the unit is old which throws off the balance of the blades and could cause this.
A humming sound, most likely.
check to see if the blower is moving it may be stuck open ac spin the blower then try ac again it worked for me .
People who hear a humming, a ringing, or a pulsation may have tinnitus or an ear infection.
The humming sound is the fuel pump. this is normal the sound is the air compressor for the ELC (Electroinc level control) it pumps air into the rear struts the level the car out when you turn on the key.
One would really have to hear it in order to determine for certain. Are there any particular conditions existing in which the humming occurs? Wheel bearings are a possibility.
Sometimes the blower is always on, at a low speed. If you have a system that turns off the blower completely, then you should hear nothing.
It's most likely to be a wheel bearing if you jack ur car up an spin each wheel if you hear a rough sound it's a wheel bearing
Vacuum leaks in the A.C. system. DO YOU hear a faint humming or whistling sound?
The heater or blower motor on my 91 previa works some time but has'nt now for the last month. I hear a humming sound that lasts for 10 seconds or so and then seems to kick out. It will do this twice with a gap of a few minutes in between when i start the vehicle in the morn.then it doesnt do this again until i let it sit for hours.i have heat but cant get the full effect because the blower wont kick in to circulate it. Also the blower only works on high when it works.any suggestions?
you have to listen to see if your fuel pump is operating when you turn your car on (do not start it) you should hear a humming sound if you dont you can tap your gas tank if you hear the sound after tapping the gas tank now try to start it if it doesnt start it the fuel pump.
put tranny fluid in it!
The blower motor is probably busted, or the blower speed switch could be busted as well, if that isn't it could be a fuse for the blower motor I would check that first and save your self alot of time and money.