Frequently Asked Questions
Aren't the filters really expensive?
Unlike some air cleaners, like the HEPA, there are no expensive filters to replace in the C-90B. The only replacement filter is an inexpensive carbon filter which removes odors and fumes.

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• What is the difference between the Friedrich C-90B and the Friedrich C-90A?

• Why does the light on my C-90 blink or flicker?

• Is the C-90B effective against mold?

• Does the C-90B electronic air cleaner produce any ozone?

• How can I buy replacement carbon filters?

• How often should I replace my carbon filter?

• Do I need to replace my pre-filter?

• Where do I get filters for my C-90A or C-90?

• How do I find a Friedrich dealer in my area?

• Where can I download an Owner's Manual?

• What are the Friedrich C-90B's dimensions?

• How often should I replace the carbon filter in my Friedrich air cleaner?

• How quiet is the Friedrich C-90B?

• Aren't the filters really expensive?

• How large an area will the Friedrich C-90B handle?

• Will the Friedrich C-90B discolor walls, drapes or furniture?

• How do I know which air cleaners are really effective?

• How much electricity does the Friedrich C-90B air cleaner require?

• How do I clean my Friedrich air cleaner?

• How do I install a carbon filter on my electronic air cleaner?

• Can I use my Friedrich C-90B with my window open?

• Why is my electronic air cleaner making a popping sound?

• Are there discounts for purchasing more than one Friedrich C-90B?