Electric Heat Air Handler Wiring Diagram B17576-02 - 208/230V Schematic & Notes

This document is a factory wiring diagram label (drawing number B17576-02, dated 3-91) for an electric-heat air handler / HVAC unit operating on 208/230 volts, not an automotive diagram. The schematic shows up to four heating elements (HTR 1-4) protected by circuit breakers (CB) and thermal limits (TL), switched through sequencer relay contacts (M1-M8, R1, R2). It also depicts the evaporator blower motor (EM) with run capacitor (RC), high/low speed taps, a blower time delay relay (BTDR), a 24-volt control transformer (TR) with 208/230-volt primary taps, and low-voltage thermostat terminals (R, OT3, OT2, OT1, OTC, C, E, W2, W1/W2, O, G). Legends include a wire color code (White, Black, Red, Yellow, Blue, Green, Purple, Brown, Pink), a component code, and a wiring code distinguishing factory and field wiring at high and low voltage. Five installation notes cover splicing unused motor leads, selecting transformer terminal 3 for 230 V or terminal 2 for 208 V, converting the blower to slow speed by swapping the black lead for the yellow lead at BTDR terminal 1, referencing composite low-voltage wiring diagrams, and wiring the optional Emergency Heat Relay (EHR) with an outdoor thermostat. Field wiring must conform to the National Electric Code.