Hello @CCSR79 

This is an unusual one for me - a first, actually. Have you ever tried NOT using the unit in Auto mode, to see what your air quality readings are? You can play around with the airflow speed settings and see if that makes any difference in the air quality readings. Have you ever seen poor air quality alerts either on the screen or within your App?

Air quality on the app is always exactly the same.  No changes to the sensor, it’s just a long green line.  There actually has never been any changes now that I think of it.  All readings are always at zero, with the exception of the temperature. 

Hi @CCSR79 

Kelly raises a valid point.

The auto function reacts to changing in the air quality. If there aren't changes past the minimal recommended level, then the purifier wouldn’t record any reading past the Good/Green line. If this is the case, my suspicion is that the air flow you are feeling is from the devices continuous monitoring setting. 

It is my understanding that all air expelled from the purifier passes through the filter set. As you stated the filter set you’ve removed is visibly clean, I suspect no particles larger than that visible to the eye have passed into or attached themselves to the outer shell. The material captures particles as small 2.5 micrometre. To put this into perspective of size comparison, a human hair is around 70 micrometres in diameter, making PM2.5 around 30 times smaller. 

The other possible scenario and less likely in my opinion, is that the onboard sensor is faulty or blocked, meaning it isn’t according recording the air, and as a result is unable to send this data to the app. If this were faulty, you should have been presented with a warning. View Dyson HP04 - Air Quality Sensor Fault/No Humidity Reading | Dyson Community for an example of this warning. 

For peace of mind, here are a few of my own recommendations, using the community as a guide:

1. Reset the purifier to its factory settings - 'Power Cycling/Restarting' your air treatment machine | Dyson Community
2. Thoroughly clean the purifier - Keeping your purifier performing at its best | Dyson Community
3. Become familiar with the graphs - Viewing your air treatment machine's air quality graphs | Dyson Community
4. Review how the filter life is calculated in the app - How is the filter life calculated and displayed in the App? | Dyson Community

If you still it is not reacting to changes in the local air, you could try the following:

1. Use an aerosol, such as deodorant near to purifier. The auto function should enable and increase the airflow to deal with the increased pollutant in the air.
2. Likewise, blow out a candle or use incense near by.

If this fails, the last resort is to contact Dyson. The Purifier range has a 2-year guarantee, where they replace or repair for free. 

David. 

Thank you David.  There’s no errors, and prior to living where I am now, I had a construction site literally 20 feet from my windows and yet the air was always reading as great.  Since I have a friend with allergies, I bough another purifier to keep in my living room (where the TP09 currently is), and that one on auto mode kicks into high and low multiple times during the day, especially when the door is open a while.  I guess my dyson has been faulty all along and I had no idea!  Good to know it’s still under warranty.  I’ll reach out!