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Troubleshooting
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7.0 TROUBLESHOOTING
Use this section to assist in troubleshooting your unit. Also refer to 5.0 - Alarm Descriptions. Sug-
gestions are grouped by product function for convenience.
!
WARNING
Only qualified personnel should perform service on these units. Lethal voltage is present in
some circuits. Use caution when troubleshooting with power on. Disconnect and lock out
power before replacing components. Use caution and standard procedures when working with
pressurized pipes and tubes.
!
CAUTION
When using jumpers for troubleshooting, always remove jumpers when maintenance is
complete. Jumpers left connected could override controls and cause equipment damage.
Table 21 Blower troubleshooting
Symptom Possible Cause Check or Remedy
Blower will not start
No main power Check L1, L2 and L3 for rated voltage.
Blown fuse or tripped circuit breaker (CB) Check fuses or CBs to main fan.
Overloads tripped Push reset button on main fan overload. Check amp
draw.
No output voltage from transformer Check for 24 VAC between P24-2 and P24-1. If no
voltage, check primary voltage.
Control fuse blown or circuit breaker tripped Check for 24 VAC between P4-4 and E1. If no voltage,
check for short. Replace fuse or reset circuit breaker.
Table 22 Chilled water troubleshooting
Symptom Possible Cause Check or Remedy
Chilled water or hot
water/steam valve
not opening
Motor operates but valve won’t open Check linkage for adjustment and be sure that it is
tight on the valve.
Modulating Motors
No 24 VAC power to motor Check linkage for adjustment and be sure that it is
tight on the valve.
No signal from control Check DC voltage on printed circuit board in motor.
Terminal No. 1 is grounded and No. 3 is positive. DC
voltage should vary from 0.8 to 2.0 VDC or above as
temperature control is varied below room temperature
on cooling valve or above room temperature on
heating valve.
Motor not working Remove wires on terminal No. 1 and No. 3 from the
motor (do not short). With 24 VAC power from TR to
TR jumper terminal 1 and 2 on motor to drive open.
Remove jumper to drive closed, if motor fails to work,
replace it.
Actuator Motors No 24 VAC power to motor Check for 24 VAC between P22-3 and P22-5 (open),
or P22-1 and P22-5 (closed).