Have a 2012 Lexus ISC Hardtop Convertible. When the heater and or A/C is on a humming sound like a motor sounds appears. If I shut down the heater the sound goes away.

SOURCE: Thumping sound under dash when start or shut down.

I take a shoot here you can try this. try pulling the fuse or fuses that go to your heater blower and heater controls. If it stops check your heater blower it may be going bad, if you find nothing there, leave the blower unplugged and try turning your key on and see if you still hear it. If so I would think that the heater control is mess up and open and close the air blend door or you may have a wire shorted out under the dash some where.

SOURCE: sudden overheat

hi  ernie try changing the thermostate first as this can cause this  D

SOURCE: The fan on my 2004 SAAB 93 convertible will not shut off.

I would suspect that the cooling fan relay ( in a relay / fuse box under the hood) is stuck. There are 2, a high and low speed relay. Pull one and see if the fan goes off. Once you have identified the culprit, see if there is an identical relay in another location that you can swap into place to verify the problem is fixed.

SOURCE: 93 convertible top wont go down

This happenrd to me the first few times after filling the tank. When the roof stops push the switch to up then back until movement stops then go back to down, eventually it will get rid of all the air in the system and the roof should start to work.

SOURCE: Heater/AC fan motor keeps running after car is shut off

that's normal when hot, but should't run down the battery. if severly overheats ffnd/fix that problem. the other will probably dissapear . if not excessively hot then the fan heat sensor is faulty....