Troubleshooting Procedure - Penn A421 Series Installation Manual

Table 4: Fault codes
Fault code Definition
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. See Figure 4.
The voltage must be between:
- 102 VAC and 132 VAC for 120 VAC applications
- 177 VAC and 264 VAC for 208/240 VAC applications
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 15 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 15, 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.
22 A421 Series Electronic Temperature Controls with Off-Cycle Defrost Installation Guide
System status
Output is off
Solution
To reset the control, press
MENU. If problems persist,
replace the control.