HVAC FAQs in Columbia, TN — Questions Homeowners Actually Ask

The short list: clogged filter, frozen coil, low refrigerant from a leak, failed capacitor, dirty outdoor coil, or duct leaks. Start with the filter and the thermostat (Cool, not Fan). See ice? Cooling off, fan On, let it thaw, then call if it happens again. Full breakdown on the AC repair page.

Turn cooling off and the fan On so house air melts the ice. Do not chip at it — coils bend and puncture easily. Lay a towel near the indoor unit; melt water can overwhelm a slow drain. Check the filter while you wait. A thawed system that freezes again has a cause that needs a tech.

No. Refrigerant is sealed in and never used up. Yearly top-offs mean a leak that is getting paid for but never fixed. The honest choices are a leak search and repair, or, on an old unit, weighing that repair against replacement.

On the hottest, most humid days, long runs are normal — Columbia systems are sized for design days, and July afternoons sit right at them. It is a problem if the house loses ground all day, the air feels damp, or the unit never cycles even in the evening. Those point to low charge, dirty coils, duct leaks, or a system that is simply undersized or worn out.

Set what your house can hold without the system running ragged — for most Columbia homes that is 72–75 while home. Cranking it to 65 does not cool faster; systems cool at one speed. If 74 feels sticky, that is a humidity problem, not a temperature problem.

A breaker that trips at start-up is the circuit protecting the house from a part drawing too much current — a compressor struggling to start, a weak capacitor that can no longer help it start, a short in the outdoor fan motor, or a breaker itself gone weak with age. Reset it once. If it trips again, leave it off: each restart pushes more current through the fault, and a cheap capacitor problem can turn into a compressor problem. Tell us whether it trips the instant the unit starts or after a few minutes of running — that timing alone splits the likely causes in half.

AUX is automatic backup the heat pump calls on for short help — defrost, very cold mornings. EM is a manual setting that shuts the outdoor unit off and heats with strips alone. EM is for a broken heat pump until it is fixed. Full answer on the heat pump page.

That is defrost, and it is normal. The system melts frost off the outdoor coil, steam rises, the fan pauses, then heating resumes. Ice that builds into a solid shell and never clears is the broken version of the same picture.

Yes, with help. Output per run drops as air gets colder, so AUX heat covers the gap in short stretches during cold snaps. A heat pump that cannot hold the house at 35 degrees outside, or runs AUX all day at 45, has a fault, not a climate problem.

Get it checked. A bang can be duct metal popping with heat — harmless — or delayed ignition, where gas lights late with a small whoomp. Delayed ignition is hard on the heat exchanger and gets worse. New, louder, or with a gas smell: system off, call.

Check the thermostat, filter, and breaker once each. Then protect the pipes: open sink cabinets on outside walls, drip faucets, keep the house above 55 any safe way you can, and call. Pipe damage in a crawl space costs more than the furnace repair that caused the night. See the emergency page.

No. Cold alone is not a reason. Leave it on Heat and let AUX come and go — short AUX runs in a cold snap are normal. EM heat turns the outdoor unit off and heats on strips alone, at a much higher cost. Use it only when the heat pump cannot run at all, and switch back to Heat as soon as it is fixed. Full answer on the heat pump page.

It is an error code. Count the short and long blinks and write the pattern down — or video it through the sight glass — before resetting anything, because a reset can clear the code the tech needs. The chart lives inside the blower door, which is our side of the panel. Give us the pattern when you call. More on the heating repair page.

Between 40% and 50% feels right for most people here. Above 55% the house feels sticky even when it is cool, and musty smells and window condensation start. Measure it — a thermostat or a cheap gauge — before buying anything. Answers on the air quality page.

Different jobs. Cleaning removes what is inside the ducts. Sealing and repair stop cooled air from leaking into the attic or crawl. Hot rooms and high bills are nearly always the second problem. We inspect and show you photos before recommending either. See duct services.

Heat rises, upstairs ducts are long and often leaky, and many homes have no return air upstairs. The fix is duct repair, sometimes zoning — rarely a bigger unit. Thermostats & zoning page lays out the options.

MERV 8–11 suits most home systems. Higher MERV in a small return chokes airflow and can freeze the coil. Match the filter to the return size and blower, and change it every 30–90 days — more often with pets or during peak summer run time.

Cold duct, wet crawl air, thin or torn insulation. The drip soaks insulation and feeds the musty smell in the house. Fix is sealed, insulated ducts — and a dry-enough crawl. Crawl space page.

The sources do not agree, so we will not fake a schedule. The EPA does not set a routine interval — it points to cleaning when there is a clear reason: visible mold, pest debris, heavy dust and debris, or remodel dust. The duct-cleaning trade group talks about every 3 to 5 years. We look first, show you photos, and clean only on a reason. See duct services.

For narrow jobs, yes. A UV light at the coil can help with growth on the coil and musty start-up smells. A media filter catches more dust and pollen than a basic filter. Neither fixes humidity, a wet crawl space, or a clogged drain — those get fixed at the source. Air quality page explains the order we work in.

The thermostat reads only the air at its own wall, and sun, drafts, or a nearby vent can fool it — and a second thermometer in another room can read two or three degrees different on placement alone. If one room is always about five degrees off, that is air not reaching or returning from the room: ducts and airflow, not the thermostat. See thermostats & zoning.

Square footage alone does not answer it, and any chart that says it does is a starting point, not a size. Windows, insulation, ceiling height, duct condition, and sun load all move the real answer, and an oversized unit is a humidity problem in Columbia, not a luxury. The full sizing answer — including the starting-point ranges and the load calculation that overrules them — lives on the replacement page, so this site gives one sizing answer in one place.

Depends on the house and the fuel at the house. A heat pump heats for less than electric strips through most of a Columbia winter and cools in summer — a strong fit for all-electric homes. A gas furnace gives the hottest supply air in cold snaps and suits homes that already have gas. Dual fuel pairs the two. One number to hold onto: Middle Tennessee Electric puts auxiliary strip heat at about three times the electricity, so any setup that leans on AUX heat all day loses money quietly. Full comparison on the home page and heat pump page.

Thermostat off while the power is out, so the unit does not take the surge when it returns. Once the lights are steady, wait about 15 minutes before switching back on. Walk the outdoor unit for debris or damage, check the breaker once, and check the drain. Breaker trips again, a hum with no start, or a burning smell means leave it off and call. Full list on the emergency page.

More than most people guess. Middle Tennessee Electric says heating and cooling can account for more than half of a single-family home’s energy use, especially in extreme weather. That is why small faults — a clogged filter, AUX heat stuck on, ducts leaking into the crawl — show up on the bill before they show up as a breakdown.

Four small things: a clear path to the indoor unit and the electrical panel, pets settled in a closed room, the thermostat easy to reach, and anything you have noticed written down — when it started, what changed, any blink pattern on the furnace light. None of it is required. All of it shortens the visit.

We will give you the visit terms and honest ranges of what a symptom usually turns out to be, but not a repair price — a price quoted blind is a price built to change at your door. The repair price that counts is the one in writing after the system has been tested, and that is the one we stand behind.

Yes, and you should on any big ticket. Bring the other quote if you have it. We check the same scope — model numbers, duct and electrical lines, permit, warranty split — and price ours on that same scope, in writing. If their quote is the better buy on the same work, we will say so.

Finding the fault is usually the first 30 to 45 minutes: thermostat, airflow, electrical tests, and charge readings, in that order. A repair with a part on the truck — a capacitor, contactor, igniter, flame sensor, a cleared drain — is often finished inside the same visit. What stretches a visit is a part that has to be fetched, a leak search that has to rule out sections one by one, or duct and crawl space findings that change the job. We tell you which of those you are in before the clock matters, and the price in writing comes before the repair work, not after it.

Not one. Age-times-cost, half-cost, and weekly-cost rules all circulate and they disagree. We price both with the same scope and weigh age, history, comfort, and bills with you. Replacement page shows the factors.

AC and heat pumps: roughly 10–15 years in the Southeast, shorter without maintenance, because they run both the long humid summer and the winter. Furnaces: 15–20 years. Humidity and runtime here are harder on equipment than in drier states.

Emergency: no cooling in extreme heat with a health risk at home, no heat on a cold night, burning smells, a breaker that keeps tripping, water through a ceiling. Can wait: one off room, a mild noise, a high bill, a degree-off thermostat. When in doubt, call and describe it — we will tell you honestly which list it is on.

We walk payment options on any replacement quote, in writing. Whoever you use, watch for deferred-interest offers where one late day triggers back-interest on the full amount, and get the term, rate type, and total cost on paper. The financing page lists the questions to ask.

Mostly, if your system is eight years old or more, you have more than one system, or you know you will not book tune-ups on your own — a plan buys visits that actually happen, priority booking in the first heat wave or cold snap, and a repair discount. A young system under warranty can be fine paying per visit. Get the terms in writing either way. Maintenance page.

Brand matters less than the install: sizing, ducts, charge, and airflow decide how a system runs, and those are installer work. Compare quotes on the same scope — exact models, matched equipment, duct and electrical work, permit, and parts and labour warranty as separate terms. Replacement page.

Heating and cooling in one outdoor cabinet, instead of an outdoor unit plus an indoor furnace or air handler. Common where indoor space is tight, in some slab homes, and in houses built around one. Packaged is not a quality tier — placement, duct connection, and service access are the real questions. Replacement page.

Careful with old articles: the federal §25C credit ended for equipment placed in service after December 31, 2025. Utility incentives change too. We check what is current for your address at quote time and put only real, current incentives in writing. Financing page.