It gets hot near the switches and there is a burn mark there.

That unit is a very heavy duty machine that uses ionization to clean air. There is a high voltage power supply that is used to generate ions. The unit can release ozone and that substance has a definite smell to it. If you have ever been near a copy machine or an electric motor that sparks, you would smell ozone. The concern is whether or not it is ozone. Ozone is regulated by the manufacturers to be held at a permissible level because at high concentrations it is an irritant and can cause respiratory issues by itself. The power unit for that air cleaner is on the top near the back and you can run the machine for a while to see if that area gets hot. That would be a bad sign. All the documentation is here: http://electronicaircleaners.com/f50f1032parts.aspx But if you don't trust the unit, take it or send it back.

We will need to know the make and modek in order to help you.

Either your switch is not making a contact internally or the wire that runs from the motor to the switch is loose or not connected, or that speed is burned out on the motor. Those motors have a separate wire for each speed, so it's either not getting power to the motor from the switch or the that speed setting is burned out on the motor its self. I would just work around it and use the low or high setting until you can take it apart to test if the motor is getting power from the switch, if so then the motor is bad, usually the bearings go out on the motors before the wiring does. Unless your motor was on medium and was stopped for a long period and overheated that setting which will melt the wires and cause it to not work. They have a safety switch on the motors now to keep this from happening.

Check where wires attach to collector plates. Possibly there is a a burn mark there. Or these units also spark when humidity is very low.

Something is not reassembled correctly.
Check all connections, insertions, turnings, etc.
The lamp/starter need to be inserted so they "click" or "seat" firmly.
The plate needs to be inserted into the little "tracks" at the top and bottom of the plate. The contact fingers must press firmly on both sides of the plate. Bend them so they do.
The back screen needs to be inserted so the little pull-tab sticks out at the top and so the safety switch (if there is one) is depressed.
The back needs to be screwed back on firmly.
The plug needs to be inserted firmly, FIRMLY, FIRMLY into the back of the machine.
The little safety switch near the plug with the 0/- markings needs to be set to allow power to the machine (try it with power plugged in).
If all else fails, check the fuse (near the plug.)
If nothing works, call customer service (Vollara is the new name for EcoQuest) at 1-800-989-2299. They can walk you through these steps if you ask them to, then give you other options. Use #16618 as your dealer referral number if you are not in touch with a registered dealer.

You will need to take unit apart to check both the and bottom. Start either at top or bottom go over the circuit path of hi voltage grid wire check for more burn marks. Insure hi voltage insulated wire coming from transformer is not broken. This will be located at bottom of unit you will have to take top pc board off and control transformer to get to hi voltage transformer, then when that is removed you will see the hi voltage connector I was talking about. That wire is soldered on and is a very delicate connection. Make sure wiring soldered. Hi voltage transformer should be ok if you did not leave unit on for a long time while you had your loose connection in the grid wire.

I would check the line fuse located near the power cord. The other thing would be the safety switch. Make sure the clip on the lint filter is making contact witht the safety switch.

The problem is you're Gas valve. If you have a volt meter, set it above 24 volts ac.When the Hot surface ignition glows, have you're meter on your gas valve terminals. Hold them there through the complete cycle, and you should have 24volts which you will, showing with power going to it, it will not open, the coil is burned out. Do not try and repair it! This has to be replaced.When the Gas valve is ready to open, you will hear a click.No gas, bad coil.This will solve you're problem, I have replaced so many of the MGV's. Good Luck, and please let me know, Thanks Shastalaker7

No. This is not repairable. You will need to purchase a new cell from your local hvac contractor.

I had the same problem and then found that it was from burning aroma candles! I will never burn them again!