33
Moderate
Carrier · Central Air Conditioners & Furnaces
Limit Circuit Lockout
Quick Answer
Error code 33 on your Carrier Central Air Conditioners & Furnaces means: Limit Circuit Lockout. This is usually fixable — see the step-by-step guide below.
Likely Causes
How to Fix It
1
Reset the furnace by turning power off for 30 seconds then back on
2
Check the air filter and all ductwork for restrictions
3
Inspect blower motor and capacitor for proper operation
4
Measure static pressure in the duct system (should be under 0.5 inches WC)
5
If code recurs, a licensed HVAC technician should inspect the heat exchanger for cracks using a combustion analyzer
Pro Tip
This fix requires some technical knowledge. If you're unsure about any step, consider contacting support or a qualified technician.
Parts You May Need
Blower motor
Blower motor capacitor
High-limit switch
Heat exchanger (if cracked)
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