I performed a single system heating maintenance on a 2023 gas system. I checked amps, capacitor, filter, electrical, drains, safeties, cleanliness, filter, and rinsed the outdoor unit. Also, I ran an air quality test. I came back having high carbon dioxide and VOCs. I spoke with the homeowner about surge protection and addressing the air quality issues. Customer was not interested in addressing the carbon dioxide via a fresh air intake. However, she would like us to send a pdf file on the Airscrubber to further investigate and educate herself.