Heil outdoor unit will not start; diagnostic indicates low-pressure or loss-of-charge fault

Safety first: Turn off power at the disconnect and breaker. Refrigerant work must be done by an EPA-certified technician; do not attempt to add or remove refrigerant yourself.

• Step 1 – Filter and airflow: Check and replace the air filter at the Heil air handler or furnace. Ensure all supply and return vents are open and unobstructed.
• Step 2 – Inspect indoor coil: Remove the access panel to the evaporator coil. If the coil is iced over, turn system to OFF and fan to ON at the thermostat for several hours to thaw. Once thawed, clean visible dust from the coil with a soft brush and coil cleaner.
• Step 3 – Check for obvious oil stains: Look at refrigerant line connections at the outdoor unit, indoor coil, and service valves. Oil stains often indicate a refrigerant leak.
• Step 4 – Reset low-pressure switch: Some Heil models auto-reset after pressure normalizes. After thawing and restoring airflow, restore power and test. If the unit still will not run and E3 persists, the system likely has a leak or control issue.
• Step 5 – Call a technician: A pro must locate and repair leaks, replace the low-pressure switch if defective, and properly evacuate and recharge the system.