Furnace No Heat: Winter 2026 Checklist

This checklist is for the 2026–2027 heating season. It was updated on October 31, 2026. ENERGY STAR says to check the heating system in the fall, because contractors get busy once winter comes. Nothing below is a deadline, a price, or a stock claim.

If you smell gas, stop

Goodman IOG-2037B, under “What to do if you smell gas”:

• Do not try to light any appliance.
• Do not touch any electrical switch; do not use any phone in your building.
• Immediately call your gas supplier from a neighbor’s phone. Follow the gas supplier’s instructions. If you cannot reach your gas supplier, call the fire department.

The same warning says installation and service must be performed by a qualified installer, service agency or the gas supplier.

Make the thermostat call for heat

Goodman’s startup procedure says to adjust the thermostat to a setting above room temperature. On a call for heat, the thermostat contacts close and the control board receives 24 VAC on the W terminal. ENERGY STAR’s maintenance checklist includes checking thermostat settings as part of a contractor checkup. This page does not tell you to change fan settings; the Goodman steps cited here do not.

Read the code, then open that page

Write down the characters or the flash pattern before you cut power. How to read a furnace LED flash code shows where Carrier, Goodman, Lennox, Rheem and Trane put the light. Rheem 10 is a one-hour lockout that alternates with the code that caused it; Rheem 10 says to read that second code.

What you see	What the manual names	Open
Blower runs, no heat	Goodman EE3: circulator runs continuously, no furnace operation; primary limit open; blocked filters. Carrier 33: limit or rollout switch open; dirty filter. Lennox red slow / green on: primary or secondary limit open; check the air filter. Trane E04: open limit; dirty filters.	Goodman EE3, Carrier 33, Carrier 13, Lennox, Trane E04
Inducer runs, burners do not light	Goodman EE2: pressure switch circuit is not closed; blocked flue and/or inlet air pipe; pressure switch hose blocked, pinched, or connected improperly. Lennox red off / green slow: pressure prove switch open, or blocked inlet or exhaust. Carrier 31: pressure switch did not close or reopened.	Goodman EE2, Lennox, Carrier 31
Ignition tries, then stops	Goodman EE0: lockout after 3 ignition retries; igniter worn or misaligned; flame sensor coated or oxidized. Rheem 11: failed ignition, then one-hour lockout 10. Carrier 34 and 14: oxide on the flame sensor; defective hot surface igniter. Trane E2.1: flame never sensed after 3 tries.	Goodman EE0, Rheem 11, Carrier 34, Carrier 14, Trane E2.1
Furnace still runs, weak flame signal	Goodman EE6: flame sensor coated or oxidized. Rheem 12 is the low-flame-sense code on that control.	Goodman EE6, Rheem 12
Rollout switch open	Goodman E11: open rollout switch, furnace fails to operate. Trane E04 says never to leave limit switches jumpered, and its rollout checks are for a technician.	Goodman E11, Trane E04

The part finder lists every code whose document names the flame sensor, igniter, pressure switch, filter, or limit switch.

York, Amana, American Standard and Bryant use the same idea with different lights. York 7 red flashes is three failed ignition trials. York 3 red flashes is a pressure switch that stayed open, and the manual names a blocked vent pipe. York 4 red flashes is an open main limit, and a dirty filter is on that list. Amana EE0, EE2 and EE3 are the lockout, open low-stage pressure switch, and open primary limit on the *CVC96 / *MVC96 chart. American Standard E2.1 is flame never sensed. Bryant 14 is ignition lockout after 4 attempts on the 926TB. On the 80% two-stage chart, Bryant 34 is the proving failure before that lockout, Bryant 33 is the limit fault and names a dirty filter, and Bryant 32 is the low-heat pressure switch with a restricted vent on the list. The longer writeups are the ignition lockout and open limit guides.

Outdoor terminations and snow

Goodman IOG-2037B requires every vent and intake termination to be at least 12 inches above ground level or the anticipated snow level. EE2’s corrective action is to inspect the flue and inlet air piping for blockage, proper length, elbows, and termination. Look at the outdoor pipes for a termination buried in snow. Do not take the pipes apart, and do not jumper the pressure switch. If the termination is clear and EE2 remains, the hose, inducer, and switch checks in that entry are technician steps.

Filter, and what the cards below are

The Department of Energy Energy Saver guide says to clean or replace filters on furnaces once a month or as recommended. ENERGY STAR says to inspect, clean, or change air filters once a month, and that a dirty filter can increase energy costs and damage equipment. Goodman EE3 says to check filters and ductwork for blockage. Use the size printed on the old filter. The cards below are text links only: four Filtrete sizes whose listing titles were read on Amazon on October 25, 2026, plus a search for other sizes. They are not a fit for your furnace.

Goodman says a qualified servicer cleans the flame sensor with emery cloth or steel wool. Rheem recommends that cleaning at the beginning of the heating season, with fine steel wool or a Scotch Bright Pad, by a qualified installer, service agency or the gas supplier. The steel-wool card is that material. The cleaning-kit button is an Amazon search, because neither manual names a branded kit. Carrier 14 and Carrier 34 also name oxide on the flame sensor and mark the steel-wool cleaning as a technician step.

The multimeter card is a consumer tool. Trane E6.3 gives an igniter resistance of 37 to 70 ohms at about 75°F and assigns the check to a technician. Do not use it as a reason to work on the gas valve or the control board.

This page does not link a gas valve. Goodman says installation and service must be performed by a qualified installer, service agency or the gas supplier.

When to call a licensed technician

Call a licensed HVAC technician for the gas valve, the igniter circuit, the control board, vent sizing, and any limit or rollout switch that has opened. Trane E04 says never to leave limit switches jumpered. ENERGY STAR’s heating checkup, done by a contractor, includes gas connections, gas pressure, burner combustion, and the heat exchanger. Schedule that in the fall; ENERGY STAR notes that contractors get busy once winter comes. That is planning advice from ENERGY STAR, not a cutoff on this site.