Kenmore Dryer Error Code F20: Heater Relay Failure and No-Heat Troubleshooting

Updated: February 2026

When a Kenmore dryer displays F20 , it is often associated with a heater relay problem. The heater relay is typically on the main control board and acts like a switch that turns the heating circuit on and off. If the relay fails, heat can become intermittent, stop completely, or behave in a way the control detects as unsafe or abnormal.

Because a relay-related code can be triggered by other issues (like burned wiring, an open thermal fuse, or severe vent restriction), the best approach is to verify the basics first. That prevents you from buying an expensive control board when the real problem is a loose terminal or an airflow restriction.

Symptoms you may notice with F20

💡 Pro Tip: Check if there is a manufacturer-specific version of this advice in your product manual.

Dryer runs and tumbles but produces no heat.
Heat starts for a short time, then stops.
Cycle ends early with clothes still damp.
Burning smell or hot electrical odor near the rear panel or heater area.
F20 appears repeatedly even after a power reset.

Safety warning

Dryer heating circuits involve high voltage and high current. Always unplug the dryer or switch off the breaker before removing panels or touching wiring. If you see melted insulation, charred connectors, or signs of arcing, stop and consider professional service. Electrical heating problems can become fire hazards if ignored.

Step 1: Confirm proper power for electric models

On electric dryers, the motor can run on 120V even if the dryer is missing the second hot leg needed for 240V heating. A partially tripped breaker or a bad connection at the outlet can cause a no-heat complaint that looks like a relay failure.

Check the breaker: flip it fully off and fully on.
If you are comfortable and trained, measure voltage at the outlet to confirm correct supply.
If you are not comfortable with live electrical testing, call an electrician or technician.

Step 2: Fix airflow issues that stress heating controls

Restricted venting can cause overheating and can damage heater wiring and relay outputs over time. Clean the lint screen, vacuum lint around the lint chute if accessible, inspect the vent hose, and verify strong airflow at the exterior hood. If your dryer vent is long, schedule a full vent cleaning.

Step 3: Perform a reset and verify repeatability

Unplug the dryer for two to five minutes, then restore power. Run a timed dry cycle with heat selected. If the dryer consistently throws F20 during a heat call, you have a persistent fault worth diagnosing.

Step 4: Inspect heater circuit wiring and terminals

Before testing parts, do a detailed visual inspection. Many heating failures begin as a loose terminal that arcs and overheats:

Inspect spade terminals at the heating element, thermostats, and any thermal cutoffs.
Look for discoloration (brown or black), melted plastic, or brittle insulation.
Check that connectors fit tightly and do not slide off easily.

If you find a burned terminal, replace the terminal and inspect the mating tab. A new control board will not fix an overheated connector and may fail again if the connection remains poor.

Step 5: Test common no-heat parts before blaming the relay

A heater relay code can show up when the dryer commands heat but the expected temperature rise does not occur. That can happen if the heater circuit is open for any reason. With the dryer unplugged, test these parts for continuity or correct resistance (using your model tech sheet when available):

Heating element : test resistance across the element terminals. An open element means no heat.
Thermal fuse (if equipped): an open fuse cuts heat and often indicates overheating from vent restriction.
High-limit thermostat or thermal cutoff : an open safety device can stop heat and may signal chronic overheating.

When testing, remove at least one wire from the component to avoid reading through the rest of the circuit.

Step 6: When the heater relay or control board is the likely culprit

If the heating element and safety devices test good, wiring is clean and tight, and airflow is strong, then a heater relay failure on the control board becomes a more likely root cause. Relay contacts can burn or stick. In some cases, the board trace or relay drive circuitry can also fail, leading to a relay that does not energize reliably.

Control board replacement should be done carefully:

Match the part number to your exact model number.
Photograph connectors before removal so you reconnect correctly.
Inspect the console area for moisture or lint buildup that could affect electronics.

After the repair: verify stable heating

Run timed dry with heat for 10 to 15 minutes and confirm warm exhaust outside.
Run a normal load and confirm dry time and cycle behavior are normal.
Recheck the vent for strong airflow and no unusual heat buildup.

Preventing repeat heater relay problems

Relay stress increases when the heater runs too hot or too long due to restricted airflow. Keeping the vent path clear, using correct vent materials, and maintaining tight, clean electrical connections reduces overheating and electrical resistance that can damage relays and control boards over time.

What Matters Most: When dealing with Kenmore Dryer Error Code F20 : Heater Relay Failure and No-Heat Troubleshooting, patience and the right information are your best tools. You now have both.

Share this guide:

← Back to Overview

Frequently Asked Questions about Kenmore Dryer Error Code F20: Heater Relay Failure and No-Heat Troubleshooting

Is Kenmore Dryer Error Code F20: Heater Relay Failure and No-Heat Troubleshooting suitable for beginners?

Yes, absolutely. Our guide to Kenmore Dryer Error Code F20: Heater Relay Failure and No-Heat Troubleshooting explains all basics clearly.

How much does Kenmore Dryer Error Code F20: Heater Relay Failure and No-Heat Troubleshooting cost?

Costs vary depending on the provider. A comparison is always worth it.

Where can I find more information?

Right here in our expert area for Dryer Error Codes & Troubleshooting.