Troubleshooting - Penn A421 Series Installation Manual

Figure 11: Adjusting temperature in the Restricted menu

Troubleshooting

A421 Series Controls display fault codes on the LCD as
described in the following table.
Table 5: Fault codes
Fault code Definition
SF flashes Open
alternately temperature
with OP sensor or
sensor wiring
SF flashes Shorted
alternately temperature
with SH sensor or
sensor wiring
EE Program
failure
Troubleshooting procedure
1. Check for proper voltage to the A421 Control.
a. To remove the cover, loosen the two captive cover
screws.
b. Use an AC voltmeter to check the voltage between
the COM and 120 V or 240 V terminals on line-
voltage models and the two 24 V terminals on low-
voltage models. See Figure 4.
Note: The voltage must be between:
- 20 VAC and 30 VAC for 24 VAC applications
- 102 VAC and 132 VAC for 120 VAC
applications
- 177 VAC and 264 VAC for 208/240 VAC
applications
10 A421 Series Standard Electronic Temperature Controls Installation Guide
System status Solution
Output See Troubleshooting
functions procedure. Cycle
according to power to reset the
the selected SF control.
mode
Output See Troubleshooting
functions procedure. Cycle
according to power to reset the
the selected SF control.
mode
Output is off To reset the control,
press MENU. If
problems persist,
replace the control.
c. If the voltage reading is not within the required
range, check the power source and input power
wires for problems.
2. Check for proper sensor operation.
a. Disconnect all power sources to the control.
b. Use an accurate thermometer to take a
temperature reading at the sensor location.
c. Disconnect the sensor from the control.
d. Use an ohmmeter to measure the resistance
across the two sensor leads while the sensor is at
the temperature taken in Step 2b.
e. See Figure 12 to verify that the measured
temperature and resistance conform to
established temperature and resistance values.
f. If the measured values conform to the values in
Figure 12, proceed to Step 3.
g. If the sensor's measured resistance value is
substantially different from the expected value
for that temperature, check the sensor wiring. If
sensor wiring is correct, replace the sensor.
Figure 12: Temperature versus sensor resistance
3. Check the A421 for proper operation.
Note: Perform troubleshooting Steps 1 and 2
before you perform this step.
a. Disconnect the load from the output relay
terminals.
b. Make sure that you install the Parameter
Adjustments jumper so that you have unrestricted
access to adjust parameters.
c. Reconnect the sensor leads and supply power to
the control.
d. Replace the cover.
e. Check the control settings for proper values.
f. Press MENU until On appears. Press MENU again
to display the On value.
g. Press Down or Up to change the On temperature
above and below the sensor temperature until the
relay energizes and de-energizes.