4 flashes
Easy Fix
Goodman · HVAC Systems (AC, Furnaces & Heat Pumps)
Open High Temperature Limit Switch
Quick Answer
Error code 4 flashes on your Goodman HVAC Systems (AC, Furnaces & Heat Pumps) means: Open High Temperature Limit Switch. This is usually fixable — see the step-by-step guide below.
Likely Causes
How to Fix It
1
Check and replace the air filter if dirty
2
Open all supply and return registers throughout the home
3
Verify the blower motor is running during the heating cycle
4
Measure temperature rise across the furnace (compare to nameplate range, typically 30-60 degrees F)
5
Check the blower motor capacitor and clean the blower wheel if dirty
Pro Tip
This is a common issue that most users can resolve without specialized tools. Try the first step before moving on to more complex solutions.
Parts You May Need
Air filter
High-limit switch
Blower motor capacitor
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