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Troubleshooting
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8.0 TROUBLESHOOTING
Use this section in troubleshooting your unit. Also refer to 6.0 - Alarm Descriptions and Solu-
tions. Suggestions 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.
Start switch SS not making
contact (SM only)
Jumper P9-1 to P9-2. Unit should start. If unit stops after
jumper is removed, replace S1.
Blower runs but controls
will not operate
Relay R1 not making contact
(standard controls only)
Check for 24 VAC between P36-9 and P36-10. If voltage is
not present, R1 is not receiving power.
Check air switch. Jumper P36-4 to P36-7 If R1 closes, air
switch is not closing (check for blower rotation, loose wiring,
and pinched tubing.) Remove jumper.
Check for 24 VAC at R1 coil. If the voltage is present and R1
is not pulling, replace R1.
Table 22 Chilled water troubleshooting
Symptom Possible Causes Check or Remedy
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).
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.