Short answer
For AC repair in Knoxville, TN, first check the thermostat, breakers, filter and outdoor fan. If the air is still warm, a frozen coil, failed capacitor, refrigerant leak or blocked drain is the usual cause. Get the diagnostic fee and repair price in writing, and check the contractor's Tennessee license.
What should I check before calling for AC repair?
Check five things first: the thermostat setting and batteries, the indoor and outdoor breakers, the air filter, the outdoor unit's fan, and any ice or water near the indoor unit. These take a few minutes and need no tools. If they all look normal and the air is still warm, it is time for a technician.
Plenty of no-cooling calls in Knoxville turn out to be a tripped breaker or a thermostat that switched to Heat or Off. Rule those out before you pay for a visit.
- Thermostat. Set it to Cool, a few degrees below the room, with the fan on Auto. Replace the batteries if the screen is blank or faint.
- Breakers. The indoor unit and the outdoor unit usually have separate breakers. There is often a disconnect box on the wall by the outdoor unit too.
- Filter. ENERGY STAR says a dirty filter can raise energy costs and damage equipment. A clogged one can also freeze the indoor coil.
- Outdoor unit. The fan on top should spin when the system calls for cooling. Clear grass clippings, leaves and anything stacked against it.
What are the most common AC problems in Knoxville homes?
The most common AC repairs are electrical parts that wear out, low refrigerant from a leak, a frozen indoor coil, a blocked condensate drain, and a failing outdoor fan motor. Hot, humid summers keep systems running for long stretches, so worn parts tend to fail during the first heat wave of the year.
Knoxville averages 36 days a year at 90 F or hotter, and July's daily average is 78.4 F. That means long run times from June through September, and that is when weak parts show up.
| What you notice | Common cause | What a technician usually does |
|---|---|---|
| Outdoor unit hums but the fan does not spin | Failed capacitor or fan motor | Tests and replaces the failed part |
| Air from vents is warm or barely cool | Low refrigerant, dirty coil, or a compressor fault | Checks pressures, looks for a leak, cleans coils |
| Ice on the copper lines or indoor coil | Poor airflow or low refrigerant | Thaws the coil, checks the filter, blower and charge |
| Water around the indoor unit | Clogged condensate drain or pan | Clears the drain line, checks the float switch |
| System turns on and off every few minutes | Oversized unit, thermostat or electrical issue | Checks controls, sizing and wiring |
Refrigerant is not used up like fuel. ENERGY STAR notes that too much or too little refrigerant makes a system less efficient and shortens its life, so low refrigerant usually means a leak that should be found, not just topped off.
Is my AC frozen, and what should I do?
Ice on the copper line set, the indoor coil, or the outdoor unit in summer means the coil got too cold, usually from weak airflow or low refrigerant. Turn the thermostat from Cool to Off, or set the fan to On, so the ice melts. Running it frozen can damage the compressor.
Once it thaws, replace the filter and make sure supply vents and the return grille are open. If it freezes again within a day, a technician needs to check the blower, the coil and the refrigerant charge. Put towels down, because a thawing coil can overflow the drain pan.
How much does AC repair cost in Knoxville?
We do not publish prices, because the cost depends on the part, the system and the contractor, and a number on a referral site would only be a guess. What you can control is how the price is set. Ask for the diagnostic fee up front, and get the repair price in writing before work starts.
ENERGY STAR advises getting written, itemized estimates and signing a written proposal before work begins. On an AC repair, ask:
- Is there a trip or diagnostic fee, and is it credited toward the repair?
- Is the price flat-rate or time and materials?
- What warranty comes with the part and with the labor?
- Are after-hours or weekend rates different?
The things that move the price most are the part (a capacitor and a compressor are very different jobs), whether refrigerant is needed, and the age of the system.
Should I repair or replace an old air conditioner?
ENERGY STAR suggests calling a contractor to look at replacement when a heat pump or air conditioner is more than 10 years old. Age alone is not the answer. A single failed part on a system that cooled well last summer is usually worth repairing. A big repair on an old, inefficient system often is not.
Older systems that use R-22 refrigerant add a twist. The EPA notes that most HCFCs, including HCFC-22, have been phased out, with some use continuing only for servicing existing equipment. A leak on an R-22 system can be costly to recharge, which pushes many owners toward replacement. Our AC replacement guide walks through the decision.
When is a broken AC an emergency?
A broken AC becomes urgent when someone in the home is at risk from heat: older adults, infants, people with heart or breathing conditions, or pets left inside. It is also urgent if you smell burning, see sparks, or a breaker keeps tripping. In those cases, shut the system off and get help fast.
For anyone at risk from heat, move to a cooler room or a cooler building while you wait. Our emergency HVAC repair page covers what to do while you wait and how after-hours calls usually work. Whether a contractor can come out the same evening depends on the contractor, so ask when you call.
How do I choose an AC repair company in Knoxville?
Choose a company that will tell you its fees before it arrives, holds a license you can check, and puts the repair price in writing. In Tennessee, the Board for Licensing Contractors regulates contractors and home improvement contractors, and its Verify a License tool is free.
- Ask for the business name and check the license before the visit.
- Ask what brands they service. Most can work on any brand.
- Ask for references, as ENERGY STAR suggests, and call one.
- Be wary of pressure to replace a system on the first visit without a written diagnosis.
When you call the number on this site, you are connected with an independent HVAC contractor who takes calls for your area. You are never obliged to hire them. See how referrals work.
Can I fix my AC myself?
You can safely change the filter, clear debris from around the outdoor unit, reset a tripped breaker once, and flush a condensate drain line with a cup of water if it is accessible. Leave anything involving refrigerant, capacitors or wiring to a technician. Capacitors store a charge even with the power off.
Handling refrigerant also requires EPA Section 608 certification, so a refrigerant top-off is never a DIY job. If a reset breaker trips a second time, leave it off and call.
How can I keep my AC from breaking down next summer?
Book a cooling check-up in spring, before contractors get busy, and check the filter every month. ENERGY STAR recommends checking the cooling system in spring and the heating system in fall, and inspecting, cleaning or changing filters monthly during heavy use.
A spring check-up usually covers electrical connections, refrigerant level, the condensate drain and airflow. ENERGY STAR notes that airflow problems alone can cut efficiency by up to 15 percent. See our HVAC maintenance guide for the full list. Many Knoxville area homes use a heat pump for cooling, and the same advice applies.
Sources: ENERGY STAR maintenance checklist, ENERGY STAR replacement guide, ENERGY STAR hiring tips, EPA HCFC phaseout, Tennessee Board for Licensing Contractors, Knoxville climate normals via Wikipedia.