Bosch Poor Heating Performance / Heat Pump Issue

Unit in heating mode blows only cool or lukewarm air; outdoor unit may frost heavily.

Safety Warning

This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.

If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.

Possible Causes

Low refrigerant charge, Faulty reversing valve, Outdoor coil heavily iced and not defrosting properly, Outdoor ambient too low for model capability

How to Fix / Troubleshooting

Steps:

Observe defrost: In very cold weather, the Bosch unit should periodically enter defrost (H1 or similar indication). If the outdoor coil remains iced, defrost may not be working.
Clean outdoor coil: Remove debris to improve heat exchange.
Check filters: Ensure indoor airflow is not restricted.

Technician tasks: Check refrigerant charge, reversing valve operation, and defrost control. Do not attempt to service the refrigerant circuit yourself.

Repair Difficulty

Hard 4/5

Required Part

Reversing Valve Assembly

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