Green purifier light no longer comes on

That's interesting... I doubt it is the filter if the new filter did the same. It might help if you take a fan and blow it through the area behind the filter, or maybe even spraying some Lysol in it, because my best guess is that something inside the purifier is what is causing the smell. Hope this helps!

Larry, since this unit is electrostatic, you may or may not hear little crackles of sparks when it is operational. You should, however, smell a very faint odor of ozone when it is running properly. If you do not hear any sounds from the electrical plates and the air coming out of the unit does not have a little different smell than the air in the rest of the room, then the unit is not functioning properly. In my research of these units, I did see references to replacing the metal fins being required as some claimed they were an consumable element to the purifier and needed periodic replacement to function properly. However, nothing in the owner's manual says they are. It simply says to carefully clean them to avoid damaging the fins or plastic insulation on them.

Other factors to check include:
Making sure the unit has at least 12" of open space behind it.
Making sure there is 36" of open space in front of it.
Give time for dust to accumulate. The manual states that you should check the collection fins after a couple of days to see how much dust has accumulated since cleaning schedules will vary greatly depending on how dusty your home is. Dust collection may take days to start to appear.
Make sure the DRYING CYCLE light is not on when the unit is operating. This protection system is designed to remove electrical power from the fins if humidity is detected (which can easily be the case since you are advised to wash the fins in water to clean them).

If the DRYING CYCLE light is not on, you have plenty of air space around the unit, and after days you still do not see anything on the fins, then chances are the issue is internal and will require repair or replacement of parts. Be advised that this unit is no longer made and has no manufacturer supported service or parts availability. Further diagnosis and repair could quickly get costly and in most cases, you are probably better off replacing the unit.

Replace the Aprilaire #4598 Ionizer Frame Assembly to correct this condition and return unit to operation with the green light now illuminated.

if you're sure you feel a breeze (fan is working), then this won't help. but make sure the rear filter is pushing in the metal tab at the bottom, or else it won't turn on. you can hold it in with a pencil to see if the machine works. also, are your plates in correctly, are any broken ? also, check/replace the internal fuse which you can find in the back.

it needs new plate (s)

The Classic XL-15 should have 2 individual indicator lights. The 'red' light is the ionizer indicator, and the 'green' light is the ozone level indicator. Both lights should be illuminated, if the unit is operating properly. The red light should be pulsing, and the green light should be dimly lit, and brightened as the output knob is turned up - indicating a higher ozone production. If the green light is not lit, you likely won't smell the ozone. The first thing you should try, is cleaning the filter and glass ozone plate. Unplug the unit and remove the rear air filter. Clean the filter with clean water and allow to COMPLETELY air dry. Removed the glass plate by depressing the lever behind the glass plate, and gently pulling it out. Clean the glass with a half water, half ammonia (or distilled white vinegar, if ammonia not available) and an old toothbrush to clean between the mesh. Dry plate with a hair dryer and re-place plate into unit. Replace dried air filter, making sure the little tab on the bottom is secured into the interlock. Power the unit on and you should see the indicator lights and smell the fresh ozone!

the electronic cleaner can not get wet. if you put the unit back on without drying the filter paks you will short the control pak out.

This unit can be replaced on ebay for around $45.00 which is under any labor cost to repair the unit you currently have. You can always post your unit for sale on ebay for parts.

Regardless of unit the purifier plates may need replacement. How are the plates cleaned? Could it be that there is a residue from the cleaning agent present after cleaning? With new plates there is a little oil on the plates to prevent oxidation when in storage or transit. A little rubbing alcohol would do the trick.
Make sure the plates are dry before putting them back into the unit.

If the plates are seated right and clean you should see a faint purple glow on the plates when the unit is on purify.

Let me know if that's the case.

Eric

Sharper Image products are no longer supported since the have been recalled after being prov-en to be ineffective

Here is a link about the Chapter 11

Here is an EPA link about them