Frequently Asked Questions


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


The Friedrich C-90B is the newest version of our top-rated electronic air cleaner. While the basic construction of the unit is the same as the C-90A, improved internal components and design have yielded better performance. For more information on the improvements, click here.

Frequently Asked Questions

What is the difference between the Friedrich C-90B and the Friedrich C-90A?
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 the carbon filter?
Do I need to replace my pre-filter?
Where do I get filters for my C-90A, C-90B, or C90?
Where can I download an Owner’s Manual?
What are the C-90B’s dimensions?
How quiet is the C-90B?
Aren’t the filters really expensive?
How large an area will the C-90B handle?
Will the C-90B discolor walls, drapes or furniture?
How do I know which air cleaners are really effective?
How much electricity does the C-90B require?
How do I clean my C-90B?
How do I install a carbon filter on my air cleaner?
Can I use my C-90B with my window open?
Why is my air cleaner making a popping sound?