Throughout my 24 years working as a certified HVAC technician and master plumber, I have seen homeowners try to repair just about everything on their heating and cooling systems. There are some tasks that I believe homeowners should take on themselves, but there are others that they should leave to professionals like me.
When it comes to heating and cooling systems, homeowners should tackle simple maintenance projects...
DO change the air filter. Think of the air filter as your system's lungs; if the filter is clogged it will decrease the heating and cooling capacity and could prematurely end the life of the condensing unit compressor and furnace heat exchanger. Keeping it clean is simple and important.
DO keep the outside condensing unit clean. To ensure your unit is working at peak performance you should keep all debris and vegetation at least 12 inches away from it. The aluminum fins on the condensing unit should be kept clear so they can disperse the heat. You can do this by turning the power off to the unit and spraying the fins with water or air to remove dirt.
DO change batteries for the thermostat. Before each heating and cooling season starts, you should run the HVAC system to make sure it works properly.
DO adjust the vents. Only you know how your house feels so you can open or close the vents as needed to balance the air flow.
DO visually inspect the system. You can look over your HVAC system to see how it looks -- nothing invasive; just a quick glance. Many problems can be spotted this way. If it looks bad it probably needs attention.
While DIY homeowners should feel confident about the tasks above, there are other aspects of heating and cooling systems that absolutely require a professional's expertise. In my opinion, homeowners shouldn't do any of the following...
DON'T remove the front panels on the furnace. All furnaces are filled with electrical parts and circuitry -- all expensive parts that can be damaged very easily. There is also a blower motor in the cabinet that is very dangerous if the power is not off. Stay out!
DON'T touch the electrical for the outside condensing unit. This unit is typically served with 220 volts of electricity. If not properly worked on by a licensed contractor the unit can be damaged and homeowners could be harmed.
DON'T work on anything containing refrigerant. No homeowner should ever try to work on or repair any part of the system that contains refrigerant. It is very dangerous.
DON'T replace a thermostat. This may sound simple enough, but if you do not know how to replace the thermostat you can damage the electrical parts or compressor of your HVAC system.
DON'T attempt a chimney inspection. The chimney base may appear to be clear, but there can be a blockage higher up, or air may not be drafting up. Hire a professional.
Many aspects of your system may seem simple or easy to repair. Sometimes this is the case, but when in doubt always call a trusted and licensed contractor.