Picture above is how most of the HVAC contractors connect their ductwork. They just put a zip tie on it. It is faster and cheaper. But in a couple years the strap stretches and the duct will come off. This one blew off, but I slid it back on to show how they did their work. I took off all the zip ties and taped the inside and outside liners on. This was a very nice custom home. Here are a few pictures of the way we connect our duct joints.
While I was under this same crawl space, I found a gas line that didn’t have any hangers for about 16 feet and it had caused a gas leak at the connection.
Here is a couple pictures of after we hung the gas line and repaired the leak. Notice the yellow gas pipe
Here here is a picture of how we can clean a condenser coil. It is very important for the air to be able to flow freely through the coils. The coils being clogged will increase your utility bill, make the system not cool properly and make the equipment not last as long.
The most common thing I see is a dirty filter. Usually not this dirty though. A good way to remember to change your filter, is to keep a pack of them, and when you get your electric bill each month, change your filter.
Another problem we find, usually while checking the heat is a cracked or busted heat exchangers. The flame burns and the fumes travel through the heat exchangers and the warm air to heat your home travels around the outside of the heat exchanger. When they crack or bust the fumes mix with your indoor air and becomes very dangerous. It is a good idea to have your heat inspected and services every fall, before turning it on.