How a central air conditioner works, in brief
A central air system has two halves. The outdoor condenser holds the compressor, a fan and a large coil. Indoors, an evaporator coil sits on top of your furnace or air handler. Refrigerant moves between them, absorbing heat from your home's air at the indoor coil and releasing it outside.
Central AC repair almost always involves one of three areas: the electrical parts that start the equipment, the refrigerant circuit, or airflow across the indoor coil. Understanding which area is involved helps explain what the technician finds.
Seven common central air conditioner problems
These are the faults we see most often during summer service calls in Metro Vancouver homes.
- Failed capacitor: the outdoor unit hums but the fan or compressor will not start. Capacitors weaken with heat and age and are one of the most frequent repairs.
- Worn contactor: this switch tells the outdoor unit to run. Pitted contacts can stop it from starting or keep it running when it should be off.
- Refrigerant leak: the system runs but blows lukewarm air, and you may see ice on the lines. Leaks need to be found and repaired, not just topped up.
- Frozen evaporator coil: usually caused by low airflow from a dirty filter or a blocked return, or by low refrigerant.
- Clogged condensate drain: water backs up and leaks around the furnace, or a safety switch shuts the system off.
- Dirty outdoor coil: cottonwood fluff, leaves and grass clippings block heat transfer and make the system work much harder.
- Thermostat or wiring problems: a dead battery, a loose wire or a misconfigured setting can look like a major failure.
Safe checks you can do before calling
Some issues have simple causes. These checks are safe for most homeowners and may save you a service call. Do not open electrical panels on the equipment or handle refrigerant lines.
- Confirm the thermostat is on cool and set a few degrees below room temperature.
- Replace or check the furnace filter. A badly clogged filter can freeze the coil.
- Check the breaker for the outdoor unit and the furnace, and make sure the outdoor disconnect is on.
- Look for ice on the copper lines. If you see it, turn the system off and run only the fan for a few hours to thaw it.
- Gently rinse loose debris from the outdoor coil with a garden hose, spraying from the inside out if you can, with the power off.
What a technician checks during a central AC repair
A proper diagnosis follows a logical path instead of guessing at parts. The technician will typically measure voltage and test the capacitor and contactor, check the compressor and fan motor amperage, measure system pressures and temperatures to judge the refrigerant charge, and look at airflow across the indoor coil.
If a refrigerant leak is suspected, the technician should look for the source with electronic detection or bubble testing. Simply adding refrigerant without finding the leak means you will likely face the same problem again next summer. Once the cause is clear, you should get a plain explanation and a quote before any repair work begins.
Problems that point toward replacement
Not every failure is worth fixing. A failed compressor in an older system, a large leak in the indoor coil, or a unit that still uses R-22 refrigerant can make repair costs hard to justify. In those cases, many homeowners replace the air conditioner with a heat pump that also handles most of the heating.
An honest technician will lay out both options and let you decide. If the system is relatively young and the problem is a single part, repair is usually the sensible path.
How to prevent the next breakdown
Most central air conditioner failures are linked to heat, dirt and neglect. A yearly spring tune-up catches weak capacitors and dirty coils before the hottest week of the year. Between visits, change the filter regularly, keep plants and fences a short distance back from the outdoor unit, and make sure the condensate drain line is clear.
During a heat wave, set the thermostat to a steady temperature rather than turning it off and cranking it down later. Asking the system to pull a hot house down quickly is when weak parts tend to fail.
Central AC repair from Able Pro
Able Pro repairs central air conditioners and heat pumps in homes across Coquitlam, Port Coquitlam, Port Moody, Burnaby, Surrey, Pitt Meadows and Maple Ridge. Our technicians diagnose the fault, explain it clearly and give a quote before starting work. We are on call 24/7, which matters when a heat wave hits and the house is getting dangerously warm.
If your air conditioner is not keeping up, call (236) 222-2222 or book a repair visit online.