Quick diagnosis
What this code is telling you
Most likely trigger
Severe airflow restriction (dirty filter)
Recommended replacement
Thermal Limit Cutoff Switch
Diagnostic path
4 ordered checks
Part fit
Exact model number required
Safety first
Before opening the appliance
Unplug the appliance before removing panels or testing internal components. Do not bypass safety switches or live-test high-voltage, gas, refrigerant, or combustion components unless you are qualified to do so.
Read the full safety disclaimerRoot cause
Why the control reported this error
The heat-pump control reports this fault when a monitored pressure, temperature, communication, or compressor condition is abnormal. Begin with severe airflow restriction (dirty filter); also verify dirty evaporator or condenser coils and defective indoor blower motor before replacing thermal Limit Cutoff Switch.
Symptoms
What you may notice
- ✓System blows cold air while set to heat
- ✓Inducer fan runs constantly
- ✓Display shows code 22
Possible causes
Check the most likely causes first
- 1
Severe airflow restriction (dirty filter)
Start here when it matches your symptoms.
- 2
Dirty evaporator or condenser coils
- 3
Defective indoor blower motor
- 4
Tripped thermal cut-off limit
Diagnostic sequence
Work through these checks in order
Stop when you find the fault. Do not perform a step that requires skills or live testing you are not qualified to do.
- 1
Check 1
Change HVAC air filter.
- 2
Check 2
Inspect indoor coil for dust mats and clean with foam spray cleaner.
- 3
Check 3
Ensure indoor fan motor turns at proper speed on heat speed tap.
- 4
Check 4
Replace main limit switch assembly.
Replacement part reference
Thermal Limit Cutoff Switch
Exact OEM part number
Model number required
Fitment note
The exact OEM part number varies by model and production revision. Verify the complete model number before ordering.
Verify the appliance model before ordering.
Manufacturers can use different parts under the same error code across model families and production revisions.
Where do I find my model number? →FixCodeDB may earn a commission from qualifying purchases made through affiliate links.
Common questions
Quick answers for this fault
What should I check first for 22?
Start with severe airflow restriction (dirty filter). If that checks out, continue through the diagnostic sequence above rather than replacing a part based on the code alone.
Does 22 always mean Thermal Limit Cutoff Switch is bad?
No. An error code identifies the condition the control detected, not a guaranteed failed part. Confirm the likely causes and wiring first. The exact OEM part number varies by model and production revision. Verify the complete model number before ordering.
When should I stop troubleshooting 22 myself?
Stop if the next step requires live electrical testing, sealed-system work, gas or combustion service, or any procedure outside your training. Unplug the appliance before removing panels or testing internal components. Do not bypass safety switches or live-test high-voltage, gas, refrigerant, or combustion components unless you are qualified to do so.
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