What is the most common part to fail on a furnace?
The most common “failure point” on a furnace is the air filter becoming clogged and restricting airflow; that can overheat the furnace and trip a safety limit, making it seem like the furnace has failed. On a Coleman Evcon furnace model DGAT095ADA, the next most common true part failures are the flame sensor, igniter, and blower-related components.
- Dirty air filter: causes overheating and repeated shutdowns
- Flame sensor: gets coated and stops proving flame
- Hot surface igniter (or ignition system): cracks or weakens over time
- Blower motor or capacitor: weak start, intermittent airflow, or no airflow
- Pressure switch: venting or draft-proving problems
- Control board: less common, but can cause no-start or erratic operation
- Turn off power to the furnace at the breaker.
- Replace the air filter (most homes need it every 1 to 3 months).
- Confirm the thermostat is calling for heat and has good batteries (if applicable).
- Check for a tripped breaker or blown fuse.
- If you are comfortable testing, use a multimeter to verify power and continuity using how to use a multimeter to test electrical parts video.
| What you notice | Most likely cause | What to do first |
|---|---|---|
| Starts then shuts off in 30 to 90 seconds | Dirty filter or flame sensor | Replace filter; clean flame sensor |
| Inducer runs, no ignition | Igniter, pressure switch, venting | Check venting; inspect igniter |
| Ignites, then short-cycles | Airflow restriction or limit switch trip | Replace filter; check registers |
| Blower never comes on | Blower motor/capacitor/control | Verify blower power; inspect capacitor |
Restricted airflow is the number one reason furnaces stop heating because it triggers built-in safety protection. Fixing airflow first prevents repeat shutdowns and helps protect the heat exchanger, limit switch, and blower system.
Last updated: February 2026
How do you reset a Coleman furnace?
To reset a Coleman Evcon furnace like model DGAT095ADA, we restore power to clear a basic control lockup and then correct the underlying issue (overheat, ignition failure, or airflow problem) so the furnace can run normally again.
- Set the thermostat to OFF.
- Turn OFF power to the furnace at the service switch or circuit breaker.
- Wait 3 to 5 minutes.
- Turn power ON.
- Set the thermostat to HEAT and raise the setpoint.
- Watch for a normal start sequence: inducer runs, igniter glows, burners light, blower starts.
Many “reset” situations are caused by a safety switch opening or a control that is protecting the furnace.
- Air filter: Replace a dirty filter; restricted airflow can trip the high-limit switch.
- Supply and return vents: Make sure registers and returns are open and not blocked.
- Furnace door/panel: Confirm the blower door is fully seated (door switch must close).
- Condensate drain (if applicable): Clear clogs; some systems shut down on drain issues.
- Flame sensor: If burners light then shut off quickly, the flame sensor often needs cleaning.
| Reset method | What it does | When to use it |
|---|---|---|
| Power cycle (breaker/switch) | Clears many control board lockups | No response, intermittent operation |
| Limit switch reset (if manual) | Restores operation after an overheat trip | Furnace overheated due to airflow issues |
| Ignition retry (automatic) | Control retries lighting after a failed ignition | Burner never lights or lights inconsistently |
A reset can get the DGAT095ADA running again, but repeated shutdowns usually mean a real problem (airflow restriction, dirty flame sensor, venting issue, or failing ignition component). Fixing the cause prevents nuisance trips and protects the heat exchanger and controls.
If you need to test power, switches, or continuity during troubleshooting, use our guide: how to use a multimeter to test electrical parts video.
Last updated: February 2026
Where is the limit switch located on a Coleman furnace?
On a Coleman Evcon furnace like model DGAT095ADA, the limit switch is typically mounted on the furnace’s hot-air side near the heat exchanger area, often on or just above the burner/vestibule panel where it can sense overheating. Many units also have additional rollout limit switches near the burners.
We usually see these safety switches in a few predictable spots:
- Main high-limit switch: on the supply air plenum side of the furnace cabinet (hot-air outlet area), often behind the upper access panel
- Rollout limit switch(es): near the burner box or burner compartment opening
- Auxiliary limits (if equipped): on the blower housing or near the heat exchanger panel
- Wiring access: typically reachable after removing the front access doors (burner door and blower door)
Most furnace limit switches are small, round or rectangular safety controls with two wires attached.
| Switch type | Typical appearance | Typical location | What it protects against |
|---|---|---|---|
| High-limit switch | Small control with 2 terminals (sometimes a probe-style body) | Supply air side near heat exchanger | Overheating from restricted airflow |
| Rollout switch | Small round disc with 2 terminals, often with a reset button | Burner area | Flame rollout / blocked venting |
The limit switch has to “feel” abnormal heat quickly. If it is tripping, the root cause is usually airflow restriction (dirty filter, blocked returns, closed registers, failing blower motor) or combustion/venting problems (rollout switch trips).
Use these safe, high-value checks first:
- Turn off power to the furnace at the switch or breaker before opening panels
- Replace or clean the air filter; confirm it is the correct size and installed correctly
- Make sure supply registers and return grilles are open and not blocked
- Check the blower compartment for heavy dust buildup on the wheel
- If a rollout switch is tripped or you smell exhaust, stop and contact Sears PartsDirect support or a qualified technician
For electrical testing basics (continuity and safe meter use), use our guide: how to use a multimeter to test electrical parts video.
Last updated: February 2026
Where is the filter on a Coleman furnace?
On a Coleman Evcon furnace like model DGAT095ADA, the air filter is usually located in the return-air path, not inside the burner compartment. Most commonly it sits behind a return grille in the wall or ceiling, in a filter slot at the furnace cabinet, or in the return duct just next to the furnace.
- Return grille filter: a large grille in a hallway, living area, or near the thermostat; the filter slides out when you open the grille.
- Furnace-side filter rack: a narrow slot where the return duct connects to the furnace; the filter slides in and out like a drawer.
- Return drop or return plenum: a filter access door on the return duct within a few feet of the furnace.
- Media cabinet (thicker filter): a separate box attached to the return side; often uses a 4 to 5 inch filter.
- Turn off power to the furnace at the switch or breaker.
- Find the large return duct (the one pulling air into the furnace, not the smaller supply ducts).
- Look for a slot, hinged door, or thumb-screw cover on that return side.
- If you do not see a slot at the furnace, check the largest return grille in the home.
- Note the airflow arrow on the filter frame before removing it; install the replacement the same direction.
| Setup | What it looks like | Where you access it |
|---|---|---|
| Return grille filter | Filter directly behind a big grille | Wall or ceiling return grille |
| 1 inch filter rack | Thin filter in a side slot | At the furnace or return duct |
| Media cabinet | Thick filter in a separate box | Return side cabinet next to furnace |
A correctly placed, correctly oriented filter protects the blower motor and heat exchanger area from dust buildup. A missing filter or a clogged filter can reduce airflow, cause overheating, and lead to nuisance shutdowns.
If you need to confirm the model number on the furnace data tag before ordering a filter or other parts, use how to find your appliance model number (and what it means for parts).
Last updated: February 2026
Why is the green light blinking on my Coleman furnace?
A blinking green light on your Coleman Evcon furnace model DGAT095ADA is a diagnostic code from the control board. It means the furnace is reporting a normal operating status or a fault (often a failed ignition or a safety switch opening) based on the blink pattern.
On most Coleman-style furnaces, the board flashes a repeating code to narrow the problem area. Common causes include:
- Ignition failure (burners never light)
- Flame not proven (flame sensor does not detect flame)
- Pressure switch open (draft inducer or venting issue)
- Limit switch open (overheating from low airflow)
- Control board lockout after multiple failed starts
Shut off power to the furnace before removing any access panel.
- Set thermostat to HEAT and raise the set temperature
- Replace the air filter; restricted airflow commonly trips the limit
- Make sure supply registers and return grilles are open
- Confirm the blower door is fully seated (door switch must close)
- Check intake/exhaust terminations for blockage (snow, nests, debris)
- If the furnace is completely dead, check the fuse using how to tell if a fuse is blown
Because this is a gas furnace, stop and contact Sears PartsDirect support or a qualified technician if:
- The furnace retries several times and never heats
- You smell gas or see soot around the burner area
- The unit lights briefly, then shuts down repeatedly
The blink code is a built-in safety feature; it prevents unsafe operation and helps protect parts like the igniter, gas valve, and control board.
| Symptom | Often points to |
|---|---|
| Inducer runs, no ignition | Pressure switch, igniter, venting |
| Lights, then shuts off in seconds | Flame sensing |
| Runs, then stops on high temperature | Airflow or limit switch |
Last updated: February 2026
