Goodman HVAC Error Code 21: How to Fix It

Q: What does Goodman error code 21 mean?

Error 21 on a Goodman AC means the high pressure switch has opened because refrigerant pressure is too high. This shuts down the compressor to prevent damage.

Q: How do I reset Goodman error code 21?

First, fix the underlying cause (e.g., clean coils, check fan). Then turn off power for 5 minutes, restore power, and set thermostat to cool. The error should clear if the issue is resolved.

Q: Can a dirty filter cause error code 21 on Goodman?

Indirectly, yes. A dirty filter restricts airflow across the indoor coil, causing high pressure. Replace the filter as part of routine maintenance.

Q: Is it safe to bypass the high pressure switch?

No. Bypassing the switch removes safety protection and can cause compressor failure or refrigerant line rupture. Always repair the root cause.

Q: How much does it cost to fix error code 21?

If DIY (cleaning coils), cost is minimal. If a technician is needed, expect $150–$300 for diagnosis plus parts/labor. Refrigerant repairs can cost $300–$800+.

Abstract

Goodman error code 21 indicates that the air conditioner's high pressure switch has opened due to excessive pressure in the refrigerant system. This is a safety mechanism to protect the compressor. Common causes include a dirty condenser coil, a faulty fan motor, low refrigerant, or a defective pressure switch itself.