Furnace Tune-Up Checklist: What a Fall Heating Tune-Up Should Include

Lowcountry winters are mild, but the first cold nights still catch a lot of heating systems off guard. A furnace or heat pump that has sat idle since spring can start with a dirty flame sensor, a clogged filter or a loose electrical connection, and those small problems tend to show up on the coldest night of the week. A fall heating tune-up is the simplest way to avoid that. Here is what a thorough tune-up should cover, what you can do yourself beforehand, and when to book it.

When to Schedule a Furnace Tune-Up

The best time is early fall, before you need heat every night. In the Mount Pleasant area that usually means booking in September or October, before the first real cold snap. Scheduling early gives you time to fix anything the technician finds without being without heat while you wait for a part.

If your home has a heat pump, it does both heating and cooling, so it benefits from two visits a year: one in spring before cooling season and one in fall before heating season.

What You Can Do Before the Visit

• Replace the air filter. A dirty filter is the most common cause of poor heating and overheating shutdowns.
• Clear the area around the furnace or air handler and the outdoor unit so the technician can work safely.
• Open and uncover supply vents and return grilles throughout the house.
• Test your carbon monoxide detectors and replace batteries. Any home with a gas furnace, gas appliances or an attached garage should have working CO detectors near sleeping areas. The EPA explains how carbon monoxide affects indoor air and why detection matters.
• Write down anything unusual you noticed last winter: odd smells, noises, short cycling or rooms that never warmed up.

Gas Furnace Tune-Up Checklist

A professional gas furnace tune-up should include these checks:

1. Check thermostat operation and settings, and confirm the furnace responds to a call for heat.
2. Inspect and clean the burners so the flame burns evenly.
3. Clean and test the flame sensor and check the hot surface igniter or pilot assembly.
4. Inspect the heat exchanger for cracks, corrosion or signs of overheating.
5. Test for carbon monoxide around the furnace and in the supply air.
6. Check gas pressure and inspect gas connections for leaks.
7. Inspect the flue and venting for blockages, corrosion and proper draft.
8. Inspect and clean the blower wheel and motor, and check the belt if there is one.
9. Tighten electrical connections and measure motor current draw.
10. Test safety controls, including the high-limit switch, rollout switch and pressure switch.
11. Clear the condensate drain on high-efficiency furnaces.
12. Measure the temperature rise across the furnace and run a full heating cycle.

Heat Pump Heating Tune-Up Checklist

Many Lowcountry homes heat with a heat pump instead of a gas furnace. A heating-season heat pump tune-up should add:

• Testing the reversing valve so the system switches cleanly into heating mode.
• Checking the defrost controls and sensors so the outdoor coil doesn’t ice over.
• Testing the auxiliary or emergency heat strips and their controls.
• Checking refrigerant pressures and looking for signs of leaks.
• Cleaning the outdoor coil and checking it for salt-air corrosion, which is common near the harbor and marsh.

If ice is already building up on your outdoor unit, see our guide to heat pump defrost problems in winter.

Signs You Need a Repair, Not Just a Tune-Up

A tune-up is preventive. If your system is already showing problems, tell the technician or book a repair visit instead:

• A burning smell that lasts more than a few minutes after first startup, or any smell of gas.
• The system turns on and off every few minutes.
• Cold air from the vents when the heat is on.
• New banging, squealing or rumbling noises.
• A CO detector alarm. If that happens, leave the house and call 911 or your gas company first.

Our guide to the warning signs your furnace needs repair covers these in more detail.

Book Your Heating Tune-Up

Mount Pleasant Heating & Air Conditioning has serviced heating systems in the Lowcountry since 2007. Book a fall tune-up through our HVAC maintenance service, or if your heat has already stopped working, see our furnace and heating repair service. For the reasons a yearly tune-up pays off, read about the benefits of heating system maintenance, and for cooling season, use our AC tune-up checklist.