For the professional, knowing what to change out and how to do it will lead to extending the life of a heating and air conditioning system. Here is an overview of common replacement issues and parts.
For Heating Parts,
the Do-It-Yourselfer in us wants to tackle installing replacement parts to save money. This can be a fools errand, as HVAC equipment is inherently very dangerous. It may also be illegal in your locale to perform this work. You are certainly opening yourself up to liability should you ever sell your home and there are subsequent problems.
This discussion is for those who are completely qualified and/or licensed as applicable to your local laws.
If you are qualified and are going to proceed, the first thing to find out is where you find the proper parts. Most heating and air conditioning parts has generic replacements which are perfectly serviceable. A qualified HVAC technician would make sure to replace parts that are the exact matches of the original. This applies to every specification including horsepower, voltage, amperage, shaft lengths, diameter and ratings. If you have a connection, parts are available from nationwide wholesalers like Johnstone Suppy or Graingers. If you live near a city of any size, a quick Google search of ("appliance parts "my city") will yield the results of local stores which will sell such parts to individuals. Make sure you bring the part with you, so that you can insure an exact replacement.
If you are changing out blowers, a variable one is a nice choice. It should be considerably quieter, more comfortable and more economical than a single speed blower. Blower motors going bad is a common occurrence. Replacement is one of the easier jobs for a heating and air conditioning professional to do.
Make sure you have the capacitor replaced at the same time. Capacitors are typically only $10-$15 and go bad all the time. They get fried with power surges. In fact, in many cases you may not need a motor at all, just a capacitor replacement. Capacitors carry an electric charge, even when disconnected and you can get a nasty shock if you do not know what you are doing. If your air conditioner compressor is running and your outside fan is not, or if the fan starts, then stops or turns slowly, your capacitor is the first thing to replace.
Blower wheels themselves can be a problem source. Axles crack and these wheels come off - binding in the process and wrecking havoc. This can be the issue instead of the motor, but a dislodged wheel can cause the motor to burn out and you will need to replace both.
It is amazing the amount of parts that the supply houses have for units going back for years and years. Things like gas valves are readily available, as are ceramic ignition coils and thermocouples. If replacing a ceramic ignition coil make absolutely sure that the power is off. The ceramic will not look hot, yet it will instantly sear your skin into a third degree burn.
When buying a new unit, make sure that you do not buy one with a polypropylene secondary heat exchanger. Units on the market with this have experienced numerous problems. The heat exchanger is key, because if it cracks, it will pump deadly carbon monoxide (CO) gas into your home. Always have a live CO detector in your home, because these heat exchangers can fail without warning and without indication that they have failed.
An expensive replacement are evaporator coils. Check the reputation of your brand of choice, because some makers are notorious for having leaky coils. Freon is ridiculously expensive to replace. Typically, it is $400 plus labor. Make sure of your evaporator coils before you ever buy a unit.
These are some of the parts which you can manage if you are a qualified professional. If you have any doubts, contact your friendly local service professional for help. Some may even let you supply the heating parts, if you are willing to waive the warranty on their work.
