The HVAC jobs you can safely do yourself, and where to put the screwdriver down

Your half of the job, in one paragraph

You can safely handle the air filter, the thermostat, the area around the outdoor unit, the supply vents and return grilles, a visual check of the condensate drain, and testing your smoke and carbon monoxide alarms. Anything that involves refrigerant, gas, electrical parts beyond the breaker, or opening sealed equipment panels belongs to a licensed technician. That split covers most of what keeps a system healthy between professional visits, and it keeps you away from the parts that can hurt you or void a warranty.

I am Brandon Quigley, and my family has run Quigley Heating & Air in Farmers Branch since 1945. I am a big believer in homeowners doing their half. A clean filter and a clear outdoor unit prevent a surprising share of the calls we get in July. Here is how to do your half well, and why the technician's half is where it is.

The filter, done properly

The filter is the single most important thing you control. ENERGY STAR's maintenance checklist recommends inspecting, cleaning or changing the filter on your air conditioner, furnace or heat pump once a month, and its heating and cooling guidance says to change it at least every three months. A dirty filter raises energy costs and can lead to early equipment failure, and ENERGY STAR notes that airflow problems can reduce a system's efficiency by up to 15 percent.

Check the size printed on the edge of the old filter, note the airflow arrow and install the new one pointing the same way, toward the equipment. Check more often during heavy summer use, if you have pets, or after any remodeling dust. As for which filter to buy, the EPA advises using the highest-efficiency filter your system's manufacturer recommends. That last phrase matters: a filter that is too restrictive for your system can choke airflow just like a dirty one. If you have a ductless mini-split, its washable filters need cleaning at least monthly, more often with pets or smokers.

Outside: let the condenser breathe

Your outdoor unit releases the heat pulled out of your house. When its coil is matted with cottonwood fluff, grass clippings and leaves, or boxed in by shrubs, it cannot get rid of that heat, so it runs longer and works harder. Walk out once a month during the cooling season. Clear debris from the top and sides, trim plants well back, and keep fences, trash cans and stored items away from it.

If the coil looks dusty, a gentle rinse with a garden hose is fine, with the power turned off at the outdoor disconnect first. Spray from the outside without force and never use a pressure washer, which flattens the thin aluminum fins and blocks the very airflow you are trying to improve. Point the mower discharge away from the unit, too. Grass clippings blown into the coil every week add up quickly in a long Texas summer.

If you have a heat pump, the outdoor unit works all winter as well, so the same rules apply in January. Keep leaves and ice from falling roof edges clear of it, and do not chip at frost on the coil. Light frost is normal and the unit clears it on its own with a defrost cycle.

Inside: vents, returns, thermostat and drain line

Make sure supply vents are open and not covered by rugs or furniture, and that return grilles have clear space in front of them. Replace thermostat batteries once a year if your model uses them. A blank or flickering display is one of the easiest no-heat or no-cool calls to avoid.

Then find the condensate drain. Your system pulls a lot of water out of the air in summer, and that water runs through a pipe, usually PVC, to a drain or to the outside. ENERGY STAR points out that a clogged drain can cause water damage and affect indoor humidity. Look at the drain pan under the indoor unit if you can see it safely. Standing water, rust or a float switch that has shut the system off are all signs of a clog. If the system has a cleanout on the drain line, ask your technician to show you how to flush it. If an overflow has already soaked a ceiling or floor, deal with the water first; the first 48 hours after finding standing water explains what to do.

In many Dallas homes the indoor unit and drain pan sit in the attic. If yours does, go up in the morning, not on a summer afternoon when the attic is dangerously hot, step only on joists or decking, and take a flashlight. You are only looking, not touching. A two-minute look a few times a summer is enough to catch a pan that is starting to hold water.

Alarms: the two-minute safety check

If your home has a gas furnace, a gas water heater or an attached garage, carbon monoxide alarms are part of your heating system whether you think of them that way or not. Press the test button on each smoke and carbon monoxide alarm, replace batteries in the units that use them, and look for the replacement date printed on the back, because alarms do not last forever. If you find a level of the house with no carbon monoxide alarm at all, fix that first. Our technicians still find homes with gas heat and no CO alarm, and we install and maintain both kinds of alarm if you would rather not climb the ladder.

Where to put the screwdriver down

Some tasks look simple on a video and are not. These belong to a trained technician, for reasons of safety, law or both. In Texas, contractors who install, repair or maintain heating and air systems are licensed, and the jobs below are the reason.

• Anything involving refrigerant: adding it, recovering it or repairing a leak
• Capacitors and contactors, which can hold a dangerous electrical charge
• Gas valves, burners and the furnace heat exchanger
• Electrical work beyond resetting a breaker
• Opening sealed blower or control compartments
• Cleaning the duct system, which can spread debris through the house
• Installing or replacing equipment

Why refrigerant is never a weekend project

Refrigerant is where most well-meaning do-it-yourself efforts go wrong. The EPA advises homeowners to work with dealers that employ EPA-certified technicians, often called Section 608 certification, because handling refrigerant safely takes training and recovery equipment. For older systems that use R-22, the EPA states that after 2020 only recycled, reclaimed or previously produced refrigerant can be used to service existing equipment, so every pound has become precious.

More importantly, a system that is low on refrigerant has a leak. Refrigerant is not used up like fuel. Adding more without finding the leak treats the symptom and guarantees a repeat. The amount also has to be right: ENERGY STAR notes that too much or too little refrigerant will make your system less efficient. Getting the charge right takes gauges, temperature readings and knowledge of the specific system, which is why our technicians measure pressures and temperatures on every no-cool call.

A simple routine by season

ENERGY STAR suggests tying checkups to the spring and fall clock changes, which is an easy way to remember. Here is a routine that fits a North Texas year without taking more than a few minutes a month.

• Every month: check the filter and glance at the outdoor unit
• Early spring: clear around the condenser, test cooling on a mild day and book a cooling tune-up
• Summer: watch the drain pan and vents, and keep the filter clean
• Early fall: test the heat before the first cold front and book a heating tune-up
• At each clock change: test smoke and carbon monoxide alarms and replace thermostat batteries if needed
• After storms: clear branches and debris from the outdoor unit

What a technician sees that you cannot

Your checks keep the system breathing. A technician's visit tells you how it is actually performing. During our tune-ups we check refrigerant levels, clean the condenser coil, inspect the visible ductwork, measure the supply and return air temperatures, check the condensation components, the thermostat and the electrical controls and safety devices, and on the heating side run a carbon monoxide test and check ignition, gas operation and motors. Those measurements catch a weak capacitor or a slow refrigerant leak months before it leaves you without cooling.

That is the difference between maintenance and repair. If you are already past the maintenance stage, my guide on an air conditioner that runs but does not cool walks through the checks to make before calling, and my guide to furnace and heat pump warning signs does the same for winter.

Handing off the technician's half

Most homeowners who keep up with filters and the outdoor unit still want a professional to handle the rest twice a year. Our Q Club plan does exactly that: a cooling visit in spring, a heating visit in fall, one standard filter replaced per system at each visit, priority scheduling and discounts on repairs. If you are wondering whether a plan makes sense for your house, my guide to whether a maintenance plan is worth it lays out what to look for, with or without us.

We serve Dallas, Farmers Branch, Carrollton, Coppell, Frisco, Garland, Highland Park, Plano, Richardson and University Park, and we service all brands. If you have done your half and something still is not right, call us and tell us what you have already checked. It saves time, and it tells the technician where to start.

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