Diagnostics
RT-SVX34F-EN
109
a. Measure the resistance of the sensor between the
connector terminals P23-1 and P23-2.
b. Measure the temperature at the MAS location.
Using the Temperature versus Resistance chart,
verify the accuracy of the MAF.
Replace the sensor if it is out of range.
2. Testing the Return Air Sensor (RAS). Disconnect the
cable connected to RAT on the ECA. Using the
Thermistor Resistance / Temperature Chart (
Table 16,
p. 35
):
a. Measure the resistance of the sensor between the
connector terminals P10-1 and P10-2.
b. Measure the temperature at the RAS location.
Using the Temperature versus Resistance chart,
verify the accuracy of the RAS.
Replace the sensor if it is out of range.
3. Testing the Humidity Sensors.
a. Return Humidity Sensor (RHS). Leave the sensor
connected to the ECA, and measure the operating
current. The normal current range is 4 to 20 mA
(milliampere). Replace the sensor if it is out of
range.
b. Outdoor Humidity Sensor (OHS). Leave the sensor
connected to the ECA, and measure the operating
current. The normal current range is 4 to 20 mA
(milliampere). Replace the sensor if it is out of
range.
Note:
Both the RHS and the OHS are polarity sensitive.
Verify that the polarity is correct before
condemning the sensor. Incorrect wiring will not
damage any of the controls, but they will not
function if wired incorrectly.
ReliaTel Air Module (RTAM) Tests
Test 1: Testing the Variable Frequency Drive
(VFD) Output.
1.
Using the procedure for VAV applications outlined in
“Test Modes“, p.55
, step the unit to the first test (Step
1). Verify that 10 Vdc is present between terminals J4-
2 and J4-1.
Note:
If voltage is incorrect, verify RTAM DIP switch
settings.
2. If voltage to the VFD is not present, verify that the wires
are properly connected between the RTRM or COMM
(Communications Module) and the RTAM.
If Step 2 checks out and the voltage is still not present at the
VFD output, replace the RTAM.
Test 2: Testing the Static Pressure Transducer
(SPT) Input
1.
With main power to the unit turned “Off”, disconnect all
of the tubing to the Static Pressure Transducer.
2. With the system MODE “Off”, apply power to the unit
and measure the voltage between J1-4 and J1-1 on the
RTAM. The voltage should be approximately 5 Vdc. If
not, check the wiring between the RTRM and the RTAM.
If the wiring checks good, replace RTAM.
3. Measure the voltage between J1-3 and J1-1 on the
RTAM. The voltage should be approximately 0.25 Vdc.
If not, check the wiring between the RTAM and the SPT.
If the wiring checks good, replace the SPT.
4. Apply 2.0" w.c. pressure to the HI port on the static
pressure transducer (SPT). Measure the voltage
between J1-1 and J1-3. The voltage should be 1.75 (±
0.14) Vdc. If not, replace the SPT.
Note:
The SPT is susceptible to interference from VFD’s.
Make sure the SPT is mounted on plastic standoffs
and is not touching any sheet metal.
Test 3: Testing the VAV Setpoint
Potentiometers
Turn the main power disconnect switch “OFF”. Check each
potentiometer listed in the table below by measuring
resistance. These potentiometers are built into the RTAM
and are not replaceable.
Test 4: Testing the VFD
1.
Verify that the keypad in control box is powered. If not,
check the power wires to the VFD and the Keypad
cable.
WARNING
Live Electrical Components!
During installation, testing, servicing and
troubleshooting of this product, it may be necessary to
work with live electrical components. Have a qualified
licensed electrician or other individual who has been
properly trained in handling live electrical components
perform these tasks. Failure to follow all electrical safety
precautions when exposed to live electrical
components could result in death or serious injury.
Static Pressure
Setpoint
0-560 ohms
(Approximate)
RTAM J7-1,2
Static Pressure Dead
band
0-560 ohms
(Approximate)
RTAM J7-7,8
Reset Setpoint
0-560 ohms
(Approximate)
RTAM J7-11,12
Reset Amount
0-560 ohms
(Approximate)
RTAM J7-5,6
Morning Warm-up
Setpoint
0-560 ohms
(Approximate)
RTAM J7-9,10
Supply Air Cooling
Setpoint
0-560 ohms
(Approximate)
RTAM J7-3,4
Supply Air Heating
Setpoint
0-560 ohms
(Approximate)
RTAM J7-13,14
