I thoroughly examined the cleanliness of 2 gas systems. Systems are from 2012 and the manufacturer is carrier. 1. Both systems have excessive dust build up within the ducts and plenums. 2. The blowers have minimal build up and should be fine for another year or two. 3. Both systems have poor filtration and this allows dust to bypass the filter. 4. The downstairs system has a compromised emergency drain pan. This makes it a major risk for causing water damage. 5. I observed that neither system has water safety switches and having them is highly recommended. 6. The upstairs system is short 600CFM on return air. This causes unnecessary wear and tear on your blower motor, heat exchanger, evaporator coil, and compressor. This wear leads to premature failure in major components.