Verify that you removed the filter bags. Verify which fan speed the product is set on. Higher fan speeds make more noise. If you hear a rattling or squeaking noise, call customer service.
Regarding AeraMax models: if your unit is making a clicking noise that is bothersome, then the PlasmaTrue Technology feature can be turned off. The PlasmaTrue technology feature on the AeraMax air purifiers can be turned off by pressing and holding down on the PlasmaTrue icon on the touch screen display panel for approximately five seconds. The PlasmaTrue Technology indicator light will turn off, letting you know that the PlasmaTrue Technology feature on the machine is turned off. Please note that if you turn off the PlasmaTrue Technology feature, it may reduce the coverage area below the AHAM certified rating.