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This OEM control transformer (part number HT01BC208) is the factory-specified replacement for the Carrier 09DE044900. The transformer steps down high-voltage line power — either 230V or 115V primary — to the 24V AC signal that energizes the entire low-voltage control circuit: thermostat, contactor coil, gas valve, and board logic. When this transformer fails, the entire system goes dark — no thermostat response, no staging, no operation whatsoever. It is often the first component to diagnose when a unit shows zero control activity despite confirmed line voltage.
Compatibility: Designed for Carrier model 09DE044900. Confirm your unit's supply voltage matches the correct primary tap (230V or 115V) before installation. Cross-references: 320659-301, 2-05757-1. Not sure it fits? Our fitment team verifies compatibility before you order — reach out before purchasing.