Heating and Cooling in an Older Home: What to Check

Short answer: Older homes often have systems that were added to, patched or replaced in pieces over the years. The things worth checking first are the ductwork, the refrigerant the AC uses, the thermostat and its wiring, the furnace's venting and safety controls, and whether the equipment is still sized for the house as it is now. Start with a filter change and a look at the thermostat, then have a technician inspect the system before you commit to big repairs or a replacement.

Safety first: if you smell gas (a rotten-egg smell), leave the house now and call 911 or Southwest Gas from outside. If a carbon monoxide alarm sounds, get everyone out and call 911 from outside. A dusty or oily smell the first time the heat runs each season is normal and can linger for a couple of days.

Why older homes need a different look

A newer system in a newer house was usually designed and installed together. In an older home, it's common to find a furnace from one decade, an outdoor unit from another, ducts from the original build, and a thermostat someone swapped in along the way. Each piece may work, but they may not work well together. Rooms may have been added, windows replaced, or an attic insulated since the system was sized.

None of that means something is wrong. It just means it's worth checking the whole system, not only the part that stopped working.

1. Ductwork

In many older homes, the ducts have been there since the house was built. Over time, joints loosen, tape dries out, flexible duct can sag or get crushed in the attic, and insulation can break down. Leaky ducts in a hot attic waste cooling in summer and heating in winter, and they can pull dusty attic air into the house.

Signs include rooms that never get comfortable, a lot of dust, whistling at vents, and high bills. Our ductwork problems guide covers what to look for and what you can check safely.

2. Refrigerant in older AC systems

Older air conditioners and heat pumps may use HCFC-22, also called R-22. According to the U.S. EPA, U.S. production and import of HCFC-22 ended on January 1, 2020. The EPA says you can keep using and servicing an existing R-22 system, and it doesn't require you to replace it. Service uses recovered, reclaimed or previously produced R-22, and the EPA notes that price and availability may change.

The nameplate on the outdoor unit usually lists the refrigerant. If your system uses R-22 and has a leak, that's a good time to talk about repair versus replacement. Our AC refrigerant leak guide explains leaks, and our repair or replace an old AC guide walks through the decision.

3. The furnace or heat source

Older furnaces can still heat well, but they deserve a careful safety check: the flue and venting, the heat exchanger, the burners and the safety switches. If the furnace is due for service, our furnace tune-up guide covers what a check-up includes. If you're weighing a new one, see our furnace replacement guide.

Make sure you have working carbon monoxide alarms in any home with gas appliances.

4. Thermostat and wiring

Older thermostats may be wired with only a few conductors, which can limit which newer thermostats will work without adding a wire. An older mercury or mechanical thermostat may also be less accurate. If you're upgrading, or your current one acts up, see our thermostat guide.

5. Sizing and the house today

Equipment sized for the house years ago may not match it now if rooms were added, a garage was converted, windows were replaced or insulation was added. A system that's too small may run constantly in summer, and one that's too large may short cycle and leave rooms uneven. A proper load calculation looks at the house as it is now.

Uneven rooms

Older homes often have rooms that run warmer or cooler than the rest. Common reasons include long or leaky duct runs, too few return vents, and additions that were tied into existing ducts. Keep vents and returns open and clear, change the filter, and have a technician measure airflow before you add equipment.

What you can do before calling

• Change the filter, and check it more often in dusty months.
• Keep vents, returns and the outdoor unit clear.
• Look at the outdoor unit's nameplate and note the refrigerant and model number. It helps when you call.
• Write down which rooms are uncomfortable and when.
• Test your carbon monoxide and smoke alarms.

What not to do

• Don't replace one piece without asking whether it matches the rest. A new outdoor unit may need a matching indoor coil.
• Don't seal ducts in the attic with standard cloth duct tape. It doesn't hold up.
• Don't let anyone top off a leaking system again and again without finding the leak.

Spring Valley and Rhodes Ranch

Spring Valley is an unincorporated town in Clark County, west of the Las Vegas Strip. Rhodes Ranch is a master-planned golf community within Spring Valley in the southwest valley. Older homes there, as anywhere in the valley, benefit from the checks above. See our Spring Valley service area page for local service.

FAQ

Do I have to replace an AC that uses R-22?

No. The U.S. EPA says you can keep using and servicing an existing R-22 system. Production and import of new R-22 ended on January 1, 2020, so service uses reclaimed or previously produced refrigerant.

How do I know what refrigerant my AC uses?

Check the nameplate on the outdoor unit. It usually lists the refrigerant type along with the model and serial number.

Should I replace the ducts in an older home?

Not always. Many ducts can be repaired and sealed. A technician can inspect them and test airflow to see whether repair is enough or sections need replacing.

Can I put a smart thermostat in an older home?

Often, yes, but older wiring may not have the extra wire some thermostats need. A technician can check the wiring and add a wire or adapter if needed.

Why are some rooms in my older home always uncomfortable?

Common reasons are leaky or long duct runs, too few returns, additions tied into existing ducts, or equipment no longer sized for the house as it is now.

What hours can I reach Colton?

Colton Air Conditioning is open Monday to Friday, 8am to 5pm. You can call or book online during those hours.

Colton Air Conditioning

Colton Air Conditioning, 6545 S. Fort Apache Rd Ste 135 #467, Las Vegas, NV 89148. Nevada contractor license 0092120. Hours: Monday to Friday, 8am to 5pm. Call (702) 738-6976 or book online during those hours.

Want routine maintenance on a schedule? See our Comfort Club maintenance plans: Gold, Platinum and Diamond tiers are all listed there.