Blower control: anti-cold-air delay and heating fan delay

What happens, in order

1. Thermostat call Y1 gives low blower speed, Y2 gives high speed, G alone gives low speed, and a W call (electric heat) gives high speed
2. A single-stage thermostat can be used; if Y1 and Y2 are jumpered the blower only runs high
3. SW6-3 ON enables anti-cold-air delay in heating: it applies when coil sensor T2 is below 82.4F, electric heat is off and Y1 is called
4. While active the blower is held off until the coil warms
5. Exit when T2 reaches 89.6F, the heater kit comes on, the system leaves heat mode, or after 15 minutes in heating
6. If the entry conditions persist for 120 seconds the blower starts at first-stage speed
7. SW6-3 OFF uses a fixed 90 second blower delay in heating, at the speed set by Y1 or Y2
8. Do not connect the B wire when pairing with a condenser that energizes the reversing valve in cooling; it would trigger the delay on a cooling call

Timings and thresholds

Models

More Bosch air handler sequences

• Dehumidification call · Cooling