If you want to get good at DIY HVAC repair or you want to eventually start your own HVAC company, you’re going to need to get really good at diagnosing or troubleshooting a system. If you’ve ever hired a professional HVAC company, you know that this is always the first step to fixing a problem. Although on the surface, you may know exactly what’s happening with a furnace or AC unit, but with further investigation, you may discover something entirely different.


The first thing you should always check is that your system has power and that the circuit breaker hasn’t tripped. You can try turning the circuit breaker for either your AC unit or furnace off and then on again to reset it. You should switch the main power off if you have fuses instead of circuit breakers. Next, you should check your thermostat and if that isn’t working, replace its batteries.

Test Your Furnace

Go to your thermostat and change it to “heat” mode. Turn it up about five degrees and wait about thirty seconds. If no air is coming out of the vents, turn it off and go to your panel door. If the switch inside this door isn’t engaged, the system won’t work. Try turning the gas off and then on again or hitting the rest switch. Turn the gas back on after five minutes and test the system to see if it works.

Test Your AC

Start by setting your thermostat to “cool” mode. Once this is done, follow the same process you did with the furnace to see if air is coming through the vents. If not, go to the circuit breaker and reset it. If it’s still not working, look for condensation underneath the AC unit. Unfortunately, dirty coils can result in freezing which may lead to normal room temperature air coming out of your vents rather than conditioned air. If this has happened, turn the system off for several hours and clean the coils once they’ve thawed.

Contact Jenin Supply Today

If you need replacement parts for your system or you have any questions while you’re attempting a DIY repair, don’t hesitate to get in touch with our HVAC supply store here in Bridgeview. We offer nothing but the highest quality furnace, air conditioner, and refrigerator supplies  Come visit us in store or give us a call today to get started.