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Honeywell HPA300 Air Purifier How-to & Troubleshooting Guide

Honeywell HPA300 Air Purifier How-to & Troubleshooting Guide

The Honeywell HPA300 air purifier model is one of the most popular household air purifiers in the market. It covers an ample space of 465 square feet and boasts of 300+ CADR rating (Clean Air Delivery Rate). Its two filters with  3-stage air purification make it highly effective in reducing household odors, allergens, and other air pollutants which are 0.3 microns or larger. However, when the air purifier develops issues, it affects its performance.

Most issues come from clogged filters, inlets, and outlets, and electrical problems. Therefore, we have come up with this manual to help you troubleshoot the common issues related to your Honeywell HPA300 and tips on maintaining optimum performance.

How do I reset my Honeywell air purifier HPA300

After changing the filter in your air purifier, the “check filter” indicator light will remain on. Resetting the Honeywell air purifier will clear all the errors, such as the change filter error. Follow the instructions below on how to perform a hard reset on your Honeywell HPA300 air purifier.

  • Press and hold the “check filters” button for more than three to five seconds.
  • The filter timer will reset, and the indicator light will stop flashing.
  • Press and hold the “check pre-filter key”  until the pre-filter error light stops flashing.
  • The air purifier can now work without errors.

How to replace the filter on Honeywell HPA 300

Follow the instructions below on how to replace all three filters in your Honeywell HPA300.

  • Press the power button on the air purifier and unplug it from the power outlet.
  • Locate the plastic two locking mechanism at the front of the unit.
  • Press the two locking mechanisms and remove the cover to access the filters.
  • Take out the circular HEPA filter and the black carbon pre-filter from the unit.
  • Remove the CPZ filter usually located behind the HEPA filter.
  • Take a clean microfibre rag and clean the interior chamber of the air purifier. You can also use a shop vac to remove dirt from corners and hard-to-reach areas.
  • Remove the new filters from their packaging.
  • Place the HEPA filters into the purifier making sure the arrows on the filters are pointing towards the air purifier.
  • Insert the new carbon pre-filter and lock it behind the tabs to hold it in place.
  • Return the front cover to the air purifier.
  • Plug the unit back to power and press the power button.
  • If the “check filter” light is still on, reset it by pressing the “check light” button for 3-5 seconds until the light goes off.

How to clean Honeywell air purifier HPA300

You should regularly clean the inside and outside of your air purifier to prevent dust from collecting and make the unit inefficient by clogging the filters. Follow the steps below to clean your Honeywell HPA300.

Clean the body of the air purifier

  • Use a soft dry microfibre cloth to wipe the dust from the outside and inside of the unit.
  • Clean off the dust from the air outlet with a dry cloth. You should never use water or chemicals when cleaning your air purifier.
  • Remove the front cover and clean it under cold running water and then let it air dry.

Clean the air quality sensor

  • You should clean the sensor every two months to maintain its functionality. If the unit is in a very dusty area, you may have to clean it more often.
  • Switch off the air purifier and unplug it from the power outlet.
  • Use a soft-bristled brush to wipe out dust and debris from the air quality sensor inlet and outlet.
  • Detach the air quality sensor cover.
  • Use a damp cotton swab to clean the air quality sensor.
  • Use a dry swab to dry the sensor.
  • Return the air quality sensor cover and front cover of the unit.

Clean the pre-filter

  • Switch off the air purifier and disconnect it from the power outlet.
  • Detach the from cover by pressing the two clips.
  • Remove the pre-filter.
  • Use a soft brush to remove dust and large dirt particles.
  • Wash it under cold running water, and then let it air dry completely.
  • Reattach the pre-filter to the unit and replace the front cover.
  • Reconnect the air purifier to power and switch on the unit.
  • Press and hold the “check the pre-filter” button to reset the pre-filter cleaning time count.
  • Wash your hands thoroughly after installing the filter.

Check this too: Germ Guardian Air Purifier How to & Troubleshooting Guide

Honeywell HPA300 won’t turn on.

Follow the troubleshooting tips when your Honeywell HPA300 won’t turn on.

  • If the air purifier does not turn on after pressing the power button, check the power cord. First, check the condition of the electrical cord and make sure it is not damaged. Sometimes pets can bite one cable preventing the current from passing through. If the cord is damaged, contact technical support for a replacement power cord.
  • Check if the cord plugs into the power outlet. If not, plug it back in.
  • If the cord is plugged in and still not working, the power outlet could be faulty. First, try connecting another appliance to the outlet to test it. Then, if the new electrical appliance does not turn on, replace the power outlet and make sure it has the correct power rating.
  • If the power outlet is working, check the circuit breaker and reset any tripped breakers.
  • If the air purifier is too old, it won’t turn on. The Honeywell HPA300 typically lasts between three and five years. After five years, it becomes less effective in cleaning the air and can break down completely. After five years of service, no need to repair it. You will have to buy a new air purifier.

Why did my Honeywell air purifier stop working?

The Honeywell air purifier uses three individual filters to remove harmful airborne pollutants from your indoor air. When these filters become clogged with dirt and contaminants, the air purifier stops working. To get your air purifier working again, you need to replace the filters and clean the device.

Why does my Honeywell HPA300 air purifier keep shutting off?

If your air purifier is not working continuously, here are some reasons and how you can fix them.

Clogged filters

Your air purifier will keep shutting off if the filters are clogged. If you live in a very dusty area, you will need to replace the filters more often. The air purifier with clogged filters will keep shutting off to prevent damage to its components. Remove the old filters, clean the unit’s interior with a dry cloth and replace the new filters then reset the unit.

The air purifier is overheating.

When it overheats, the air purifier shuts off as a safety measure to prevent the unit from damaging prematurely. Disconnect the air purifier from power and allow it to cool off, then switch it on again. To avoid the overheating issue, you could use an air purifier too small for the space, causing it to overwork and heat up. Clogged filters can also cause the unit to overheat.

Power surges

Check for electrical surges in your home. If other appliances are also shutting off, there could be fluctuating power supply in your house. Switch off power at the circuit breaker and contact a professional electrician to fix the power issues.

Faulty air purifier

Air purifiers are likely to be less stable after being in service for over three years. Over time the systems start to shut down slowly, and the unit needs a replacement.

Honeywell HPA300 air purifier troubleshooting

Below we have summarized the most common issues that can arise from your air purifier, possible causes, and solutions.

The air purifier is making a loud sound.

The Honeywell HPA300 has a noise level of less than 63dB, which is relatively low. So if you notice unusual loud noises, that’s an indication of a problem.

  • Change the fan speed to a lower speed level. The filter could be clogged and need replacing, or the filter is incorrectly installed. The germ mode is the quietest, followed by general clean and then turbo mode.
  • Look for the “check filter” indicator light; if it is on, you need to replace the filters then reset the timer. If you recently replaced your filter, ensure they are seated correctly in the unit. The HEPA filters fit snugly into their compartments while the side tabs hold the black pre-filter in place.
  • Check the cover and ensure that it is closed correctly. The unit may vibrate when it is running, and loosely installed components will produce the sound.
  • Inspect the unit for a foreign object. For example, a foreign object inside the air purifier could cause a loud rattling sound.

Strange odor coming from the air purifier

  • If the air purifier is new, it will produce a faint plastic smell during its first cycle, which disappears within a few days.
  • The air outlet should produce cleaner and fresher air into the room, but if you notice an odor, check the filters. A malfunctioning filter will not efficiently bad smell from the room. Therefore you should replace all three filters in your Honeywell HPA300.
  • The filters could also have absorbed gases to their maximum capacity. There could be a strong odor or smoke in your environment, causing the filters to clog quickly. You should deal with the source of the smell if possible and then replace the filters.
  • Inspect the interior of the air purifier for dead pests. Sometimes insects will crawl into the unit and produce a foul smell when they die.
  • If you detect the smell of plastic or a burning smell, the unit could be overheating and heating the components of the air purifier. Turn off the air purifier, disconnect it from power, and contact technical support.

Check this too: How to Clean a Honeywell Air Purifier

Air purification is not working well.

There are a couple of reasons why the room’s air quality does not improve, even after using the air purifier for a while. They include;

  • The room space is too large for the air purifier size. The Honeywell HPA300 air purifier is effective in an area of up to 465 square feet. Any space bigger than that will cause the unit to overwork, and it will not effectively clean the air in that room.
  • The filters are too clogged. You can clean the pre-filter and replace the other HEPA filters with new ones. Use clean water without detergents or chemicals when cleaning the pre-filter.
  • The air intake and outlet are blocked. Inspect the air purifier’s outlet and inlet, remove any blockage and clean them with a dry cloth to remove dirt and debris.
  • Indoor air quality is horrible. You should ventilate the room before turning on your air purifier to reduce the number of contaminants in the room. When you switch on the air purifier, close all the doors and windows.
  • The air purifier is in a corner. To increase efficiency, place the air purifier next to the worst source of air pollutants, 3-5 feet off the ground and away from corners and obstacles like furniture.


From this article, you will be able to diagnose and solve most of the issues that will affect your air purifier’s performance. However, most of these problems come from poor maintenance and incorrect use of your air purifier. Therefore, regularly clean your air purifier, check and clean the filters and ensure you place the air purifier in the right place to optimum efficiency.