Generic HVAC Repair Guides
Free step-by-step repair guides for Generic hvac.
Window AC Not Cooling
A window AC that runs but does not cool is almost always a dirty filter or dirty coils. When the filter gets clogged with dust, airflow drops and the unit cannot cool your room. A quick cleaning usually brings it back to life.
Window AC Leaking Water Inside
When a window AC drips water inside your room, the most common cause is that the unit is tilted forward instead of slightly backward. AC units are designed to drain condensation out the back. A simple tilt adjustment usually stops the leak right away.
Central AC Not Turning On
When your central AC will not turn on at all, start with the simple stuff: the thermostat, the breaker, and the disconnect switch. About half the time it is one of these easy fixes. If those check out, a blown capacitor in the outdoor unit is the next most likely cause.
Central AC Blowing Warm Air
If your central AC is running but only blowing room-temperature or warm air, the most common causes are a dirty air filter, a dirty outdoor unit, or a refrigerant issue. Start with the filter and outdoor unit cleaning — these are free fixes that solve the problem more often than you might think.
AC Freezing Up / Ice on Coils
Ice on your AC coils means airflow is restricted or refrigerant is low. The evaporator coil gets too cold, and moisture in the air freezes onto it. The number one cause is a dirty air filter. You need to thaw the system first, then fix the root cause.
Furnace Not Turning On
A furnace that will not turn on is often caused by something simple: a tripped breaker, a switched-off power switch, a dirty filter, or a failed ignitor. Before assuming the worst, walk through the basics. Many homeowners pay for a service call only to find out the power switch was off.
Furnace Blowing Cold Air
When your furnace blows air but it is not warm, the burners are either not lighting or they light briefly then shut off. The most common fix is cleaning the flame sensor — a small metal rod that tells the control board the burners are lit. When it gets dirty, the furnace lights for a few seconds and then shuts down, leaving only the blower running.
Furnace Short Cycling (Turns On and Off Repeatedly)
Short cycling means your furnace turns on, runs for just a few minutes, shuts off, and then repeats. The most common cause is a clogged air filter that makes the furnace overheat. The safety switch shuts it down, it cools off, then it tries again. Replacing the filter often stops the cycle.
Thermostat Not Working / Blank Screen
A blank thermostat screen is almost always dead batteries. If your thermostat uses batteries, swap them first — this fixes it about 80% of the time. If it does not have batteries (powered by the HVAC system), check the breaker and the tiny fuse on the furnace control board.
Mini Split Not Heating
Mini splits are heat pumps, which means they pull heat from the outdoor air and bring it inside. When it is very cold outside, they have to work harder and periodically run a defrost cycle. If your mini split is not heating, it may be in defrost mode, have dirty filters, or be set to the wrong mode on the remote.
Portable AC Not Cooling
Portable AC units struggle more than other types because they are less efficient by design. If yours is running but not cooling, the most common issues are a full water tank, a dirty filter, a kinked exhaust hose, or the room is just too big for the unit's BTU rating. The good news is most of these are easy to fix.
AC Making Loud Noise
AC noises usually tell you exactly what is wrong. A rattling sound often means loose hardware or debris. A buzzing sound points to electrical issues or a failing contactor. A screeching or squealing sound usually means a bad fan motor bearing. Identifying the type of noise helps you find the fix fast.