Service manual

T r o u b l e s h o o T i n g T r e e s • C o m b i t h e r m C t e x p r e s s t e C h n i C a l s e r v i C e m a n u a l • D – 15
troubleshooting trees
Two Speed Motor - No High Speed Motor Operation (with motor protection switch)
Is F-51 motor
protection switch (MPS) in
the start position?
Is there L1 power
supplied to terminal 21 of
K-52 contactor?
Is there L1 power at terminal
22 of K-52 contactor?
Reset switch and test
operation
No Yes
Yes
No
L1 supplied to terminal 21
from RBH/X3/300
Yes
Is K-52 coil energized
and engaged
Repair wiring between K-52/22
and F-51/2
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
No
No
No
No
No
No
No
No
No
Repair/replace F-51 MPS
Repair wiring between F-51/5
and motor
L1/14 from TB 16, L2/13 from N7
high limit through motor high limit
L2/12 from TB 14/2
Replace motor relay
Repair wiring between motor
relay and motor
Ohm out motor and replace
if necessary
Is L1 power at terminal 2
of F-51?
Is L1 power at terminal 5
of F-51?
Is L1 power at motor?
Is motor relay coil
energized?
Is L2 power at terminal 12
of motor relay?
Is L2 power at terminal 8 of
motor relay?
Is there voltage across blue/
white wires at motor?
Is motor running?
High speed motor operation
is working
Replace faulty K-52
contactor
No
Yes
Unit is in low speed
operation