Indoor unit shows E1 and stops cooling or heating shortly after startup

Safety first: Turn off power at the outdoor unit disconnect and indoor breaker. High-pressure refrigerant is dangerous; do not open the refrigeration circuit unless you are EPA-certified.

Steps to try:

• Clean the outdoor condenser coil: Remove leaves, plastic bags, and debris from the outdoor unit. Use a garden hose on low pressure to rinse the coil fins from inside out. Do not bend fins.
• Check outdoor fan operation: Restore power and observe the outdoor unit. The fan should start within a minute of compressor start. If the compressor runs but the fan does not, suspect the outdoor fan motor or its capacitor.
• Verify airflow indoors: Ensure all indoor filters are clean and supply/return air is not blocked. Poor indoor airflow can also raise system pressure.
• Check service valves (visual only): Confirm that the liquid and suction service valves on the outdoor unit are fully open (stem turned counterclockwise). Do not loosen caps with power on.

When to call a pro: If E1 persists after cleaning and confirming fan operation, a technician must check refrigerant charge and system pressures.