Rheem R802VA07542117MSA Error Code T022_F: Main Limit Switch Open
What Does Code T022_F Mean?
Fault code T022_F on the Rheem R802VA indicates that the main high-temperature limit switch has opened. This is a troubleshooting-level fault, meaning it has occurred but has not yet triggered a full lockout.
The limit switch is a safety device that monitors the air temperature inside the furnace plenum. When the heat exchanger gets too hot — typically because not enough air is flowing across it — the limit switch opens and shuts off the gas burners. The blower continues running to cool things down.
The most common cause is a dirty or clogged air filter that restricts airflow through the system. Closed or blocked supply and return vents throughout your home can have the same effect. A blower motor that is failing or running at the wrong speed is a less common but possible cause. If left unaddressed, repeated overheating can damage the heat exchanger over time.
Common Causes
How to Fix It: Replace the Air Filter and Restore Airflow
What You'll Need
- Replacement air filter (correct size for your system) 🛒 Find at FiltersFast · 🛒 Find at Amazon
- Flashlight
Steps
- Turn off power at the breaker or power switch AND shut off the gas supply valve Locate the furnace circuit breaker and flip it to OFF. Turn the gas shutoff valve to the OFF position (perpendicular to the pipe). If you smell gas, leave immediately and call your gas company.
- Check and replace the air filter Remove the air filter from the return air duct or furnace filter slot. If it is visibly dirty, clogged, or has not been changed in over 3 months, replace it with a new filter of the correct size. Make sure the airflow direction arrow on the new filter points toward the furnace.
- Verify all supply and return vents are open Walk through every room and ensure all supply registers and return grilles are fully open and not blocked by furniture, curtains, or rugs. Even a few closed vents can significantly restrict airflow and cause overheating.
- Inspect the blower area for obstructions With the power off, look through the access panel at the blower wheel. Check for excessive dust buildup on the blades, which can reduce airflow. Verify the blower wheel is securely attached and not wobbling.
- Restore power and gas, then test Turn the gas supply valve to ON and flip the circuit breaker to ON. Set your thermostat to call for heat and monitor the furnace through its heating cycle. Feel the supply vents to confirm warm air is flowing steadily.
When to Call a Professional
Contact a licensed HVAC technician if:
- The code returns after replacing the filter and opening all vents
- The blower motor seems slow or makes unusual noises
- The furnace overheats even with a brand-new filter installed
- You notice the blower is not running during the heating cycle
- The problem occurs repeatedly over several days
Sources
✓ Verified against manufacturer service manual — March 2026