Tempstar Furnace Not Igniting: Causes, Troubleshooting, and Solutions

The Tempstar furnace not igniting can leave a home cold and homeowners searching for fast, reliable fixes. This guide explains common causes, step-by-step troubleshooting, safety checkpoints, and when to contact a professional. It focuses on practical solutions and informs users of parts, costs, and preventative maintenance to reduce future issues.

Problem	Likely Cause	Quick Action
Blower Runs But No Ignition	Igniter Failure Or Flame Sensor Issue	Inspect/Replace Igniter; Clean Flame Sensor
Clicking With No Ignition	Gas Valve Or Pressure Switch Problem	Check Gas Supply; Test Pressure Switch
Ignition Sparks But Shuts Off	Dirty Burner Or Bad Flame Sensor	Clean Burners; Replace Sensor If Needed

How Tempstar Furnaces Ignite: Basic Operation

Understanding how the furnace ignites helps diagnose why a Tempstar furnace not igniting occurs. Most modern Tempstar units use an electronic hot surface igniter (HSI) or intermittent pilot with direct spark ignition.

The thermostat calls for heat, the control board powers the ignition sequence, the gas valve opens, and the igniter lights the burners. The flame sensor confirms combustion and signals the control board to keep the gas flowing.

Common Causes For A Tempstar Furnace Not Igniting

Failed Igniter Or Pilot Assembly

Electronic igniters degrade over time and are the most frequent cause of no ignition. A cracked or non-glowing HSI prevents gas from lighting.

Faulty Flame Sensor

A dirty or failing flame sensor can’t detect flame and will shut off the gas for safety, causing cycling ignition attempts or startup failures.

Gas Supply Issues

Closed gas shutoff valves, low gas pressure, or utility interruptions stop the furnace from igniting despite correct electrical operation.

Control Board Or Limit Switch Failures

The control board manages the ignition sequence; a malfunctioning board or tripped limit switch can halt ignition signals to the gas valve or igniter.

Pressure Switch And Venting Problems

A blocked or leaking vent, clogged condensate drain, or defective inducer motor can prevent the pressure switch from closing, stopping the ignition cycle.

Step-By-Step Troubleshooting For A Tempstar Furnace Not Igniting

Safety First

Before any inspection, turn off power at the furnace switch and shut the gas valve if working on gas components. If gas odor is present, evacuate the home and call the gas company immediately.

Verify Thermostat And Power

Confirm thermostat is set to heat and at a higher temp than room. Check the furnace power switch, circuit breaker, and 24V transformer voltage if available.

Listen For The Ignition Sequence

Turn the thermostat up and observe. Note whether the inducer motor starts, there is a click or glow from the igniter, and if the gas valve opens. These cues narrow the fault location.

Inspect The Igniter

Visually inspect the hot surface igniter for cracks or damage. A non-glowing or brittle igniter typically requires replacement. HSIs are fragile—handle with care and avoid touching the element.

Clean The Flame Sensor

Remove the flame sensor and gently clean it with a soft abrasive pad to remove oxidation. Reinstall and test; cleaning often restores proper flame detection.

Check The Gas Supply

Ensure the furnace gas valve is open and other gas appliances are working. If utilities are suspected, contact the gas supplier before continuing diagnostics.

Test The Pressure Switch And Venting

Inspect intake and exhaust vents for blockage from nests, debris, or snow. Confirm the inducer motor runs and the pressure switch tubing is intact and free of debris.

Examine Error Codes And Diagnostic Lights

Many Tempstar furnaces display LED codes on the control board. Record flashing sequences and consult the furnace manual or Tempstar code chart to interpret the meaning.

Common Fixes And Typical Costs

Some solutions are simple and inexpensive while others require professional service. Below are common fixes and estimated U.S. cost ranges including parts and labor.

Issue	Fix	Estimated Cost
Dirty Flame Sensor	Clean Sensor	$0 – $50 (DIY) or $50 – $120 Service
Bad Igniter	Replace HSI	$80 – $300
Failed Gas Valve	Replace Valve	$250 – $600
Control Board Failure	Replace Board	$200 – $800
Blocked Vent Or Condensate Issue	Clear Vent / Repair Drain	$100 – $400

When To Call A Professional

If troubleshooting steps do not resolve the Tempstar furnace not igniting, or if the problem involves gas valves, control board replacement, or persistent safety lockouts, contacting a licensed HVAC technician is recommended.

Call a professional immediately if there is a strong gas smell, repeated ignition attempts with no flame, or visible damage to internal components. Certified techs ensure safe diagnostics and warranty-compliant repairs.

Preventative Maintenance To Reduce Future Ignition Failures

Regular maintenance significantly lowers the chances of a Tempstar furnace not igniting. Annual HVAC tune-ups, ideally before heating season, identify wear and ensure safe operation.

• Replace filters every 1–3 months depending on use and filter type.
• Have burners, flame sensor, and igniter inspected and cleaned annually.
• Check vents and chimneys for obstructions seasonally.
• Schedule a professional inspection of gas pressure, control systems, and safety components annually.

Parts And Compatibility For Tempstar Furnaces

When replacing parts, use OEM or equivalent components specified for the Tempstar model. Using incompatible igniters or control boards can create hazards and void warranties.

Identify the furnace model number on the data plate inside the cabinet before ordering parts. Cross-reference part numbers with Tempstar or Lennox-branded parts if applicable, since Tempstar is often sold under larger manufacturing groups.

Safety Tips And Best Practices

Never attempt to repair gas components or control boards without proper training. Disconnect power before accessing internal parts, and avoid touching hot surface igniters directly.

Keep a CO detector and smoke alarm in working order. Frequent ignition failures could indicate incomplete combustion or ventilation problems that increase carbon monoxide risk.

Frequently Asked Questions About A Tempstar Furnace Not Igniting

Why Does The Furnace Click But Not Ignite?

Clicking often indicates the control board is initiating ignition but the igniter fails to light the gas or the gas valve does not open. This suggests an igniter, gas valve, or control signal issue.

How Long Should Ignition Take?

Most Tempstar ignition sequences complete within 30–60 seconds. Repeated cycles or prolonged attempts often trigger a safety lockout, indicated by an error code.

Can A Dirty Filter Cause Ignition Problems?

A severely dirty filter can restrict airflow and cause high-limit switch trips or delayed combustion, potentially preventing ignition. Regular filter changes help avoid these issues.

Is It Safe To Keep Trying To Restart A Furnace That Won’t Ignite?

Repeated restart attempts are not advised. After several failed attempts the furnace will usually lock out to protect the system. Persistent attempts may indicate a hazardous condition; call a professional.

Resources And Where To Find Help

Official Tempstar manuals and error code guides are valuable for model-specific troubleshooting. Local HVAC companies, licensed electricians, and the gas utility are appropriate contacts for service and safety matters.

Online forums and manufacturer support can help identify part numbers and interpret error codes, but professional diagnostics should be used for gas and electrical repairs.

Key Takeaway: A Tempstar furnace not igniting usually stems from igniter, flame sensor, gas supply, or pressure/venting issues. Many problems are diagnosable with basic checks, but anything involving gas valves, control boards, or persistent safety codes requires a licensed HVAC technician to ensure safe, reliable repair.