Dirty HVAC duct is the problem

She kept insisting that I should do this for her

My sister called myself and others up & told myself and others that her Heating & Air Conditioning system wasn’t laboring genuinely well. She said it hadn’t been laboring the best for months now however that it is getting worse. I don’t think why she was telling myself and others this. I think almost nothing about Heating & Air Conditioning units. I am a plumber, not an Heating & Air Conditioning repairman, and yet, I am the 1 everyone in the family calls whenever they need any kind of house service done. Because I was already coming over to my sister’s house for the holiday I told her I would take a look at her Heating & Air Conditioning system anyway. The first thing I noticed was the fact that she had vent filters on every single vent in the house. I asked why & she said that a lot of dust comes out of them. I removed 1 of the vents & the filter was full of dust. In fact, as far as I could see, the entire duct was full of dust. No wonder she wasn’t getting any heated air if all of the vent filters were so dusty. Additionally, the HVAC duct shouldn’t be this dirty either. I told her as much. I highly proposed she get a HVAC duct cleaning done ASAP. Then she would be able to discard the vent filters & I bet her whole Heating & Air Conditioning unit would toil a lot better. She kept insisting that I should do this for her. I had to remind her that I’m not an Heating & Air Conditioning professional. I don’t even have the tools, or the knowhow, to do a HVAC duct cleaning.