RT-SVX34C-EN 143
Diagnostics
T. Economizer modulates, but
system does not seem to
operate as effeciently as in the
past.
1. Comparative enthalpy setup,
RAS or RHS failed. System is
operating using Referance
enthalpy.
1. Check the return air sensor (RAS) at connector P10
by disconnecting P10 from RAT on the ECA. Check for
resistance between P10-1 and P10-2, refer to the
Resistance versus Temperature Chart. Replace the
sensor if necessary. Check the return air humidity
sensor (RHS) by measuring the operating current at
terminals RAH-1 and RAH-2 on the ECA. Normal
operating current is 4 to 20 milliamps mA. Note: The
humidity sensors are polarity sensitive, and will not
operate if connected backwards.
2. Referance enthalpy setup,
OHS has failed. System is
operating using dry bulb control.
2. Check the outside humidity sensor (OHS) by
measuring the opeating current at terminals OAH-1,
and OAH-2 on the ECA. Normal operating current is 4
to 20 milliamps mA.
3. Comparative enthalpy setup,
OHS has failed. System is
operating using dry bulb control.
3. Perform #2 above.
U. Power Exhaust will not
operate.
1. Exhaust motor has failed.
1. Check the exhaust fan motor, and replace if
necessary.
2. XFR has failed.
2. Check the exhaust fan contactor (XFR). Replace if
necessary
3. ECA has failed.
3. Perform the ECA Test Procedures discussed
previously.
4. XFSP has Failed
4. Perform the Exhaust Fan Setpoint Test Procedures
discussed previously.
V. IGV/ VFD will not operate
properly
1. RTAM has Failed
1. Perform the RTAM Test Procedures discussed
previously.
2. IGV / VFD has Failure 2. Check the IGV / VFD
3. Setpoint Failure
3. Perform the IGV / VFD Setpoint Test Procedures
discussed previously.
W. Power Exhause Fan cycles
ON/OFF
1. Space Pressure Deadband is
too narrow
1. Increase the Space Pressure Deadband.
2. Space Pressure Setpoint is too
high/low
2. Verify Building Pressure with maximum building
exhaust enabled. Adjust Space Pressure Setpoint
accordingly.
Table 78. Component Failure Mode
COMPONENT FAILURE RESPONSE NORMAL RANGE DIAGNOSTIC
(OAS) Outdoor Air
Sensor
1. Economizer in minimum
position. Will not modulate.
-55 to 175 F
680K to 1.2K
Heat and cool failure output at
RTRM J6-7 to J6-6 and RTRM
J6-8 to J6-6. Heat and cool
LED's blink at ZSM. Check at
RTRM connector P8, between
P8-1 & P8-2.
2. ODM3 will not cycle off (runs
continuously).
-55 to 175 F
680K to 1.2K
Check at RTRM connector P8.
(RAS) Return Air
Sensor
1. Economizer operates using
Reference Enthalpy
0 to 209 F
90K to 7.1K
ECA LED 4 Flashes. Check at
ECA connector P1 between
P10-1 & P10-2.
(MAS) Supply Air
Sensor
1. Economizer in minimum
position, will not modulate.
0 to 209 F
90K to 7.1K
ECA 8 flashes.
(OHS) Outdoor
Humidity Sensor
1. Uses Dry Bulb operation and
economizes if below 60 F DB.
4 to 20 mA
10 to 90% RH Honeywell
C7600A.
ECA 6 flashes.
Check at ECA OAH-1 and OAH-
2 by measuring current draw.
Table 77. Troubleshooting (continued)
SYMPTOM PROBABLE CAUSE RECOMMENDED ACTION
To Next Page
Loading...
