Air Conditioner Not Cooling? Hither'southward What You Should Troubleshoot.

Our experts explain how to repair the most common causes of central ac service failures.

Introduction

Our experts shows you easy DIY solutions for the virtually mutual primal air conditioning repairs. You'll exist upwardly and running sooner and will salve the expense of a service call.

Tools Required

Materials Required

  • Capacitor
  • Compressed air
  • Condenser fan motor
  • Contactor
  • Fuses

DIY Air Workout Service Repair

When central air conditioning service fails during a estrus spell, you may accept to wait days for an HVAC repair technician or an ac contractor to show upwards, and you'll probably pay at least several hundred for the repair. Just if you're comfortable working effectually electricity and are willing to spend about $50 on parts, y'all tin probably repair your air conditioning service yourself in about two hours and salve about $225 on parts markup and labor.

We talked to local HVAC repair technicians to get their all-time practise-it-yourself Air conditioning fan repair and maintenance tips. These tips volition assist you with the near common "low cooling" and "no cooling" problems. You'll need an inexpensive multimeter, a voltage sniffer, an array of insulated screwdrivers and a socket gear up.

If these AC repairs don't work, at least you've covered the most common failures, and your service guy can concentrate on finding the more than elusive trouble. Plus, with the new parts, y'all'll probable add years of breakdown-gratis ac. Hither's how to start.

Why Is My Air Conditioner Not Cooling the House?

Make Sure the Problem Isn't the Furnace

Set your thermostat to Air conditioning mode and lower the temperature setting. If the furnace fan kicks in, the problem isn't in the furnace. If the fan doesn't run, try resetting the furnace excursion breaker. If the fan still won't start, call a pro — the fixes shown here won't work.

Next, bank check the outside condensing unit of measurement. The compressor (which sounds like a fridge) and fan should be running. If not, follow the troubleshooting and repair procedures shown here.

Circumspection: Plough Off the Ability

Turn off the A/C and furnace breakers in the primary electric panel before pulling the outdoor disconnect or removing the condensing unit'due south access panel. Then use a voltage tester on the wires coming into the contactor to make sure the power is actually off.

Ac Doesn't Piece of work? Buy Parts

The Ac contactor (relay) and get-go/run capacitor(s) (see illustration below) fail about oftentimes and are inexpensive. So information technology's a prophylactic bet to buy and install those parts right away, especially if your air-conditioning service unit of measurement is older than five years. The condenser fan motor can as well fail, simply information technology runs well-nigh $150 — hold off buying that unless you're sure that'southward the culprit.

To buy replacement parts, observe the nameplate on the condensing unit of measurement (not your furnace). Jot downwards the make, model and serial number (or have a photograph). Get the parts at an appliance store, furnace dealer or online.

Projection step-by-step (8)

Step 1

Acquire the Anatomy of a Primal Abode Air Conditioner

Primal home air conditioner service systems consist of two major components: a condensing unit that sits exterior your house, and the evaporator coil (often referred to every bit an A-coil) that sits in the plenum of your furnace or air handler. The refrigerant in the A-coil picks upward the heat from your domicile and moves information technology to the outdoor condensing unit of measurement. The condensing unit fan blows outside air through the condensing whorl to remove the oestrus. The condensing unit houses the three parts replaceable by a DIYer: the Air conditioning contactor, the start/run capacitor(s) and the condenser fan motor. The condensing unit also houses the compressor, but only a pro can replace that. The A-coil has no parts that tin be serviced by a DIYer.

diagram of a central home air conditioner

Step two

Close Off the Power

  • Open the electrical box next to the condensing unit and pull the disconnect block straight out.
  • Check inside the box with a voltage sniffer to make sure the power is really off.

air conditioning service shut off the power

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Step 3

Clean the Condenser Coils

  • Aim your garden nozzle up into the top of the condenser roll to remove the crud buildup under the hat.
  • Work all the way around the coil. Then aim the nozzle down and affluent the debris down the coil fins.
  • Arrange the nozzle to a gentler stream and shoot h2o directly into the coils to flush out any remaining droppings.

clean condenser coils on air conditioner

Step 4

Test the Fuses

Many disconnect blocks contain two cartridge fuses. Check them before you keep with repairs. A diddled fuse is a sign of a failing part inside the condensing unit of measurement. And so don't only supersede it and recall you've solved the problem. Instead, supervene upon the parts, install new fuses, and fire upwardly the unit of measurement. If information technology blows once more, phone call a pro—you've got more serious problems.

How to Bank check Fuses In the Disconnect Cake

  • Ready your multimeter to the lowest Ohms calibration and bear upon the red and black leads to reverse ends of each fuse.
  • If y'all get a numerical reading, the fuse is expert.
  • A nil, a minus symbol, or an infinity symbol (∞) indicates a blown fuse.

air conditioner fuse block pull out

Footstep 5

Inspect the Inside of the Access Console

Follow the electrical conduit from the business firm — that'southward where you'll notice the admission panel. With the ability off, remove and store the access-panel retaining screws and remove the panel. Before you replace any parts, check for rodents' nests or prove of chewing on wires and electrical connectors.

If you lot observe broken wires or chewed insulation and can safely handle electrical repairs, discharge the capacitor first. Then repair the wires and make clean out the nest. Otherwise, phone call a pro.

How to Discharge a Dual Start/Run Capacitor

  • Remove the capacitor from the retaining subclass.
  • Then touch an insulated screwdriver betwixt the HERM (or "H") concluding and the Common (or "C") terminal.
  • Practice the aforementioned between the FAN (or "F") concluding and the "C" terminal.
  • On single-manner capacitors, but make a brusk betwixt the 2 terminals.

inspect access panel in air conditioner

Step half dozen

Supplant the Start/Run Capacitor(s)

All ac service units take at least one capacitor. The capacitor stores electricity and releases it during compressor and condenser fan startup to requite both motors an actress jolt of power. And it smooths out voltage fluctuations to protect the compressor and condenser fan motor from harm.

Capacitors can dethrone slowly, providing less startup power over time. Or they can fail in an instant. Gradual capacitor failure tin can go unnoticed for a long time, stressing the compressor and condenser fan motor windings, resulting in their early on failure. Since capacitors are cheap, it pays to proactively replace yours about every 5 years.

How to Supplant a Capacitator

  • Take a photo of the wires earlier disconnecting anything (you may need a reference subsequently).
  • Belch the stored energy in the old capacitor.
  • Apply needle-olfactory organ pliers to pluck one wire at a fourth dimension from the old capacitor and snap information technology onto the corresponding tab of the new capacitor. The female crimp connectors should snap tightly onto the capacitor tabs.
  • Wiggle each connector to see if it's tight. If it'south not, remove the connector and curve the rounded edges of it so it makes a tighter fit on the tab.
  • When you've swapped all the wires, secure the new capacitor.

WARNING: Discharge the capacitor before disconnecting wires or removing it from its bracket.

Install the new air conditioner capacitor

Step seven

Replace the Air-conditioning contactor

An AC contactor is a $25 mechanical relay that uses low-voltage ability from the thermostat to switch 220-volt high-amperage current to the compressor and condenser fan. Air-conditioning contactors can article of clothing out and are at the top of the list of mutual air conditioning service failures. Even if your Air-conditioning contactor is working, it pays to replace it every 5 years or so. Unscrew the sometime Air conditioning contactor earlier removing the wires. And so movement the wires to the new unit (Photograph half-dozen).

HVAC Troubleshooting Photo vi: Swap out the Ac contactor

  • Yank a connector off the sometime contactor and motility it to the aforementioned location on the new part.
  • Tighten the connectors where needed.
  • Secure the new contactor in the condensing unit of measurement.

replace the ac contactor

Footstep 8

How to Test Your Repairs

  • Reinstall the admission panel and disconnect block.
  • Plow on the excursion breaker and furnace switch, so set the thermostat to a lower temperature and wait for the AC to start.
  • The compressor should run and the condenser fan should spin.
  • If the compressor starts only the fan doesn't, the fan motor is nearly likely shot.
    • Shut off the power and remove the screws effectually the condenser encompass.
    • Lift the cover and remove the fan blade and motor.
    • Reinstall the blade and secure the embrace.
    • Then repower the unit and see if the fan starts.
    • If it doesn't, y'all've given it your best shot—information technology's time to phone call a pro.

Replace the fan motor in air conditioner

Be Patient at Startup

AC units and thermostats have built-in delay features when they're shut downwardly and then repowered. The filibuster can exist as long as 10 minutes. And, if you've subscribed to an energy-saving device from your local ability utility, the unit tin accept even longer to reset. If you lot've installed the parts shown and reinstalled the disconnect block, repowered the excursion billow, turned on the switch at the furnace, moved the thermostat to AC style and lowered the temperature below the indoor temperature, and the unit doesn't fire upwardly after 30 minutes, it's time to telephone call a pro.

Originally Published: May 20, 2022