Hoover Dirt Finder (light) not working

The sensor is dirty. The next time you change the bag, leave it off and the cover as well. Plug the sweeper in and turn it on for a few seconds. The lights should blink then run steady. This is the best way to blow out dust. It should be done outside.

There's a microphone inside the tube the dirt runs up. It listens for dirt coming up the tube. They just go bad and there's no making it better. You can either replace that entire assembly or ignore it. Fairly easy to replace. I'll include the part so you know what you're looking at.
Good luck! The Vac Dr.

http://vacuummedic.com/product.php?id=481

Inspection of the circuit board found that the 470uF capacitor looked damaged. I replaced it and I now have the Green and Red lights are working correctly.

take the bag out and the filter,put the coveer back on and start it up.see what the light says.if there is a clog somewhere and air is not getting into the bag it will read full.if that workd then put the filter back in and start it up.when the bag is in and hooked up does it expand when you turn it on.try putting the bag in and no cover and see what the bag does.please leave feedback

I had the same problem with a hoover windtunnel 6200 - u5477-900. I removed the flexible hose from top of the plastic tube running vertically along the right side of the back of the vacuum. When I used a flashlight to look into the plastic tube, I could see a clog at the bottom, where the flexible hose curved frontwards towards the brushes. I then removed the 2 screws holding the vertical plastic tube to the vacuum. When I disconnected the plastic tube from the flexible hose at the bottom, I found a clog of dirt and dog hair. After removing the clog and reassembling, the clean / dirty light now moves back and forth from red to green.

The Hoover uses a small microphone that is positioned in the plastic housing that the end of the hose fits into, just behind the bag compartment. What happens is that when dirt comes up the hose and hits the 90 degree corner, just before it enters the bag, the microphone picks up the sound and transmits that info to the electonics that controls the lights. Sometimes the microphone will stick and the red light will stay lit. If you take a screwdriver and give the microphone area a sharp tap with the handle of the screwdriver, this will often jar the microphone and it will begin working again. If not, it may need to be replaced. NOTE: this function does not affect the cleaning efficiency of the vacuum. Your vacuum will still work normally whether the dirt sensor is working or not. It is a totally unrelated function to the vacuum itself.

The sensor may be bad, or it may be coated over with dirt. Re,ove the hose at the back of the vacuum, the head of the sensor is down inside that opening, reach in there and clean it off and see it that corrects the problem, if not replace the sensor.

check out the switch that activates it. go to thehooverstore for a complete listing of hoover machines. I'm sure you'll find your machine listed along with an exploded diagram of the machine

Does this happen at both Dirt Finder Sensitivity settings?

check to make sure the settings didn't get inadvertently switched to the hi position, move the switch back and forth from high to reg a few times, then leave it on reg.

remove and hand wash the primary filter and secondary filter, dry throughly and replace them in the vacuum.

if none of this works, you will need to have the vacuum serviced, or if it is still working, just don't pay attention to the dirt-finder. the dirt sensor on your vacuum is located in the suction tube and is generally not accessible enough to clean without taking the vacuum apart.

hope this helps,
trin