Rheem RKKB-A180 wont fire

[cfcitywide]

Model RKKB-A180CL35E Ser 2D6606ADAAF2302118777 3 draft inducers on this unit. Tech support at local counter says all motors would be calling at once on call for heat ( not sure about that). From left to right , motor one bad (240v to motor no operation) motor 2 ON at call for heat motor runs 240 volts, motor 3 no operation 65 volts. Checked the board which has Hi/lo called for heat in both stages and I get 240 volt at Lo terminal and 80 volt at Hi terminal. I neeed a IOM and schematic for this unit. Are all 3 Motors calling on 2 stage demand or is it firing in low for X mins then to Hi with 2 motors then to 3? need IOM and schematic. My objective is to determine if I have a bad relay on the board which feeds the #3 motor... This motor is good jumped out to confirm.
Bonus question ... anyone know what size filters for this unit?

[cfcitywide]

Can anyone direct me to sequence of oreration sheet on this RKKB perhaps a tech support # other than the local hung over counter guy?

[automig]

what like this page 5?

it looks like your failed motor has to make a draft switch before it goes into first stage of heat.

[cfcitywide]

This is perfect. do you happen to have a schmatic. I need to determine where the warp switch is to initiate the relay for the 3rd draft inducer. It's only getting 65 volts at he motor and 80 volts of the hi fire connection at the board.

[cfcitywide]

what like this page 5?

it looks like your failed motor has to make a draft switch before it goes into first stage of heat.

OPERATING SEQUENCE
This unit is equipped with a two stage
integrated direct spark ignition control.
NORMAL HEAT MODE
A. Call For First Stage (low fire) Only:
1. Zone thermostat contacts close, a
call for first stage (low fire) heat is
initiated.
2. Control runs self check.
3. Control checks the high-limit switch
for normally closed contacts, each
pressure switch for normally open
contacts, and all flame rollout
switches for continuity.
4. Control energizes each inducer.
5. Control checks each pressure switch
for closure.
6. If each pressure switch is closed, the
control starts a 30 second prepurge

Now I need to determine why I only have 65 volts at motor #3 and 80 volts at the Hi terminal on the board. Thanks again for the info. I,m Thinking it a bad board relay.