What Your AC Contractor Should Be Checking During a Tune-Up (And Why It Matters)

May 12, 2026

By Coastal Air Plus | Serving Myrtle Beach and Charleston, SC Since 1947

We get it. Most homeowners have no idea what they are actually paying for in a tune-up. Here is something most HVAC companies would not tell you: a tune-up that takes less than 45 minutes probably was not a real tune-up. Our techs take their time. If a tech showed up, glanced at your outdoor unit, changed a filter, and was back in the truck in 20 minutes, you paid for something that looked like maintenance but was not. We serve homeowners in Myrtle Beach and Charleston and we want you to be an informed consumer, whether you use us or anyone else. Here is what a professional AC tune-up should cover. See it in action on our residential maintenance page.

The Electrical Components: Where Most Failures Start

  • Capacitors. The capacitor is what starts the compressor and fan motors. It degrades over time and is the single most common cause of AC system failure in summer heat. A tech should measure capacitor microfarad ratings with a multimeter and compare them to the rated specs on the label. A capacitor reading 10 to 15 percent below rated capacity should be replaced. One reading 20 percent or more below is a failure waiting to happen.
  • Contactors. The contactor is the electrical switch that sends power to the compressor. Contactors develop pitting on their contact points over time, which causes resistance, heat, and eventually failure. A visual inspection should confirm the contacts are not significantly pitted or burned.
  • Electrical connections. All wire connections at the disconnect box, the capacitor, the contactor, and the control board should be inspected for corrosion, looseness, and proper torque. In a coastal environment, salt air accelerates corrosion on electrical connections faster than most places. This is not something you skip.
  • Amp draw. The technician should measure the actual amp draw of the compressor and fan motors and compare them to the rated values on the nameplate. A motor drawing significantly above rated amps is working too hard, indicating a mechanical problem or low refrigerant.

Refrigerant System

  • Refrigerant level check. This requires gauges. If a tech does not connect gauges to your system, they did not check your refrigerant level. Low refrigerant means reduced cooling capacity and, over time, compressor damage. The check involves measuring operating pressures and comparing them to expected values for the current conditions.
  • Check for leaks. If refrigerant is low, a leak must be present because refrigerant does not deplete in a properly sealed system. The tech should check common leak points: the Schrader valves, service valves, and coil connections.

Coils and Airflow

  • Condenser coil cleaning. The outdoor coil pulls heat out of your home and rejects it to the outside air. A dirty condenser coil is like trying to cool your home with a blanket over the outdoor unit. In a coastal environment, salt deposits and debris accumulate quickly. The coil should be cleaned with an appropriate coil cleaner and rinsed.
  • Evaporator coil inspection. The indoor coil should be inspected for dirt buildup and signs of microbial growth. A tech cannot always fully clean the evaporator coil without removing the access panel, but they should at least look at it.
  • Blower motor and wheel. The blower moves air across the evaporator coil and through your ductwork. A dirty blower wheel reduces airflow, reduces efficiency, and can cause the coil to freeze. It should be inspected and cleaned if necessary.
  • Airflow measurement. In a thorough tune-up, the tech should measure airflow at the supply registers to confirm the system is moving the volume of air it was designed to move.

Condensate System

  • Drain line flush. The condensate drain removes the moisture your system pulls from the air. In coastal South Carolina, algae grows fast in warm, moist drain lines. The drain should be flushed and treated with an algaecide tablet. A tech who does not address the condensate drain is setting you up for a flooded air handler by August.
  • Drain pan inspection. The pan under the evaporator coil should be inspected for standing water, rust, and cracks. Standing water means the drain is already slow.

Thermostat and Controls

  • The thermostat should be calibrated and confirmed to be cycling the system on and off at the correct temperatures. The tech should also test the safety switches, including the float switch in the condensate pan that shuts the system off if the drain backs up.

Red Flags for Poor Service

A tune-up that does not include gauge readings. For more background, see whether you should really need an AC tune-up and our full AC maintenance checklist. means refrigerant was not checked. A visit under 30 minutes means several items on this list were skipped. A tech who cannot explain what they found means they were not really looking. A quote for refrigerant recharge without identifying the leak source means you will be back in the same position next summer.

Be straight with them. Ask questions. Any good technician will welcome them and sit down with you to walk through what they found. We take our time on every visit and we are transparent about what we find. Not better than every contractor out there, just different in that we take our time and are straight with you about what we find with every visit and walk customers through what we found. That is how we have done it for over 75 years.

At Coastal Air Plus, creating lasting relationships is what we are all about. We look at each system one at a time. Schedule your tune-up with us and see the difference. coastalairplus.com/request-service or 843-238-3838. You will not be oversold. Rest easy. Simple. Reliable. Coastal Air Plus.