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Home AC Repair – What to Do When Your AC Won’t Start

air conditioner fan behind grille
Image by Pixabay

If you’ve turned on your air conditioner and it won’t start, there are a number of issues that may be at fault. Here, we’ll go over some simple home AC repair work that homeowners can perform at minimal cost.

Home AC Repair Tools

First, there are a few tools you’ll need before starting out, including:

  • A multimeter (to make sure the power is off)
  • An insulated screwdriver (i.e. with all plastic on the handle)
  • Work gloves
  • Safety goggles
  • Nut driver
  • Adjustable wrench

Also, before doing any home AC repair work, make sure all power to the system is shut off.

Reasons Your AC Might Not Turn On

If your air conditioner won’t turn on, it may be for one of the following reasons:

  • The thermostat may not be set to “cool,” or it may need new batteries.
  • The circuit breaker may have flipped.
  • The outdoor condenser may not be switched on.
  • The air filter may be completely clogged.
  • The drain pan is full.
  • You have a faulty fan motor.
  • The capacitor or contactor in the outdoor unit may have failed and need to be replaced.

The final issues are a bit trickier to fix than the others, so it’s important to follow the right steps.

Diagnosing the Compressor

Start by testing the compressor. Making sure everything is turned on, go outside and watch the compressor unit as it cycles on. If it clicks and hums, you probably need a new capacitor or fan motor.

On the other hand, if it clicks without doing anything at all, the contactor may have failed. Home AC repair in any of these cases is fairly straightforward with the steps described below.

Checking the Fan Motor

If the unit turns on, but the fan doesn’t move, then the problem may be the fan motor. One way to test if it’s the fan and not the capacitor is to try kick starting the fan when the unit is on. Using a screwdriver or stick, get the fan blades moving. If they start spinning, you have an issue with the capacitor. If not, it’s likely a fan motor issue.

Replacing the Fan Motor

To replace the fan motor, start by turning off the power to the unit. This is done both at the breaker switch and at the line disconnect by the condenser. From there, remove the access panel (generally where the electrical wires connect) and snap a picture of the assembly inside. You’ll want this as a reference later because you’ll be disconnecting some wires.

Unscrew the top of the condenser unit and turn it so it’s a little offset. Follow the wires inside down to the control cabinet and detach them each. From there, you’ll be able to remove the fan motor top. Take a measurement from the fan blade to the lid to make sure you get the blade at the right height during reassembly.

The next step is to remove the fan blade. Using a wrench, remove the set screw from the side of the fan’s shaft and pull the fan off. You may need a wheel puller if the fan blade is especially stuck. Otherwise, wiggling the shaft with a wrench should do the trick.

Flip the lid over again, undo the bolts holding the motor in place, and carefully remove it from the assembly, threading the wires out the sleeve. Bolt your new motor in place, thread the new wires into the sleeve, replace the bolts and the blade (making sure it’s at the right height), and place the lid back into offset position on the condenser.

Finally, thread the wires back through into the control cabinet, making sure they’re tight enough not to get tangled in the blade. Reattach all the wires in the cabinet, screw everything back together, and give the fan a few turns. If it seems to catch on anything, you’ll probably need to adjust the fan height or wires.

Replacing the Capacitor

The capacitor is something like a large battery in your condenser unit. It stores electricity and gives the fan blowers a boost when it cycles on. Again, before starting repairs, shut off power to the unit.

When replacing it, open the access panel to the AC unit. The capacitor looks like a can with three terminals labeled COMMON (C), HERM (H), and FAN (F). After removing the capacitor and before detaching the wires, use an insulated screwdriver to discharge it. It’s very important that you not touch any metal on the screwdriver while doing this. Also, work gloves and glasses are highly recommended.

Use the screwdriver to bridge the C and F terminals, then C and H. There will be sparks, so be careful. Once you’ve discharged the capacitor, detach the wires, and insert the new capacitor (generally less than $40) into the bracket. Reattach the wires and replace the cover.

Replacing the Contactor

If the contactor needs replacing, again make sure all power is shut off to the unit. The contactor should be in the same cabinet as the capacitor.

Take note of where all the wires are connected, remove the old contactor, and replace it with a new one (about $25 at most hardware stores). Reattach all wires, shut the panel, and restore power once again.

cartoon repair person

Image by Dmitry Abramov from Pixabay

Additional Home AC Repair Information

Note that after performing these repairs and restoring the power, your AC may take a while to restart. Most systems have a delay period built in, so it could take about 10 minutes before it cycles on again. If it doesn’t after about a half hour, you may need to call a professional.

If these home AC repairs don’t work, there may be more complex issues afoot. At that point, you may be best off calling a professional for further testing.

In addition to DIY repairs, a home warranty can help you save more on home AC repair work. AHS covers locations throughout the US, including North Carolina, Texas, and Florida.

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