My central air conditioner units won't work

by Dadan

Follow this step, if the central ac unit is completely OFF.

Check breaker and fuse ONLY

This is JUST MY OPINION, ALWAYS call tech - Dadan

Someone ask a question and the question was “why does my central air conditioner not working?” and I scratch my head. I didn’t know where to start.

I will try to scratch the surface of the question.

Our first approach is to LOOK and LISTEN

That is the first step to troubleshooting by the way. We will only discuss what to look and listen for. There is NO DIY or FIY info here. Ok, let begin - Since, the indoor units provide the power source to the thermostat; we will start from the air handler unit first.

Let’s said, we turn ON the central ac unit and it would not turn on, it is completely off. The first thing, we need to know is, which part of the central ac unit is not having power. To do that, we need to separate the indoor from the outdoor.

The indoor and the outdoor unit have separate breaker!

The best way to determine if it has power for the indoor unit is, we will need to turn the fan from AUTO to ON. When the fan comes ON, it means we have power for the indoor unit and we move to the outdoor unit.

Or much easy way, if a programmable thermostat is power by the indoor unit, we could look at the thermostat screen. If the screen lit, it has power for the indoor unit.

So than, the outdoor unit is the only component that is not coming ON and we need to know why. We could checks the fuses box near the condenser unit; it is within hand REACH from the condenser unit. Within the fuse box, there should be a handle, we pull it out. There is two cartridge fuses. Use Ohm meter to check it.

After checking the fuses and it is goods. The next task, we need to listen for sound. If the outdoor unit is making some humming or click sound, we will need tech to look at it – sorry, I stop here!

If the fuse box is not within hand REACH, there should be breaker panel within 5 feet of the condenser unit. Check the breaker to see if it in the ON position or the OFF for the condenser unit.

Let’s going back to the indoor unit, what happen if the screen didn’t lit and the fan didn’t come on? There we will focus on the indoor unit.

There is a switch (it the same as light switch) that turn ON and OFF the air handler. Find the switch and look at what position it is in. The switch is within hand REACH.

If it in the ON position and the air indoor unit is not coming ON, the next thing is to check the breaker for indoor unit. If the breaker for the air handler is in the ON positive and there is not sign of power, we need to call a tech.

If the indoor or outdoor units blow the original fuse, and you put in the second fuse, it blows the fuse again. Have tech check your HVAC unit.