HVACopediaGoodman · Furnace
4 flashes Primary or auxiliary limit open
What the control is telling you
A limit switch opened. The circulator blower runs and the furnace does not fire until the limit closes. Usually too little air over the heat exchanger.
Applies to: GMES9, GCES9, AMES9, ACES9, VMES9, VCES9 (single stage, 92% and 96%)
Likely causes
- Failed primary or auxiliary limit
- Dirty filter, restrictive ducts, wrong blower speed or failed blower
- Loose wiring in the limit circuit
Test and repair steps
- Turn off power before repairs.
- Check the limits and replace if bad.
- Check filters and ductwork for blockage. Clean or clear them.
- Check blower speed and performance. Correct the speed or replace the blower.
- Tighten any loose wiring.
Settings for these units
- Normal status displays (7-segment) · Goodman/Amana GM9S96/AM9S96
- Normal status displays (7-segment) · Goodman/Amana GM9S80/AM9S80
- Normal status displays (7-segment) · Goodman/Amana GM9C96/AM9C96
- Minimum recommended filter size · Goodman/Amana GM9C96/AM9C96
Models that show this code
57 models in Goodman/Amana *MES9 single-stage
Other codes on the same units
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Source: Goodman Service and Troubleshooting GMES9*/GCES9*/AMES9*/ACES9*/VMES9*/VCES9* (RS6612016r3) , Troubleshooting Chart p.52; LED table p.44. Summarized in our own words; check the original manual for your model.
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For licensed technicians. Gas, electrical and refrigerant work must be done by a qualified, licensed person. Shut off power and gas before servicing, never bypass a safety control, and follow the manufacturer’s manual for the exact model; it and local codes always take priority. HVACopedia is not affiliated with any manufacturer; brand and model names only identify the equipment.