Indoor unit shows H1 and no warm air is produced at the start of heating

Note: On many Pioneer heat pump models, H1 is an informational code indicating defrost or preheat, not a failure.

Steps to try:

• Wait 5–10 minutes: During H1, the outdoor unit may be defrosting or the compressor may be warming up. The indoor fan may be off to avoid blowing cold air.
• Observe outdoor unit: Check if steam is rising from the outdoor coil (normal during defrost) and if the fan stops temporarily.
• Check for repeated H1: If H1 appears constantly and heating never resumes, there may be a defrost control or sensor issue.
• Power reset: Turn the system off for 5 minutes, then restart in HEAT mode and monitor behavior.

When to call a pro: If H1 never clears and no heat is produced, a technician should check defrost sensors and outdoor PCB operation.