CHK AFA Solenoid Circuit
electrical
Description
AutoFresh Air Exchange relay coil circuit problem: shorted when energized or open otherwise, and the unit only alarms.
Activation Conditions
A problem has been detected in the AutoFresh Air Exchange relay coil circuit. If this alarm is activated while the control system is calling for AFAR to be energized, the circuit is detected shorted. If this alarm occurs at any other time, the circuit is detected open.
Unit Behavior
Alarm only.
Reset Conditions
Auto reset when circuit is normal, or alarm may be manually reset using the display mounted keys or by turning the unit off, then back on again.
Corrective Actions
1. Check Relay a. Inspect relay socket and connection pins inside the control box. Verify that there is no damage to relay, and no damaged or corroded connections. b. Check resistance of coil (terminals 1 and 2). Refer to Section 2.11 for specifications. 2. Check Power and Wiring a. Check for power at fuse F7 terminal A inside PM as well as F12. Must have minimum 11 VDC. If not, check PM circuit and fuse F1. b. Check fuses F1 and F7. Verify correct fuse (see Figure 2.7). c. Check for power at PM-3 terminal. Replace PM. d. Set the AutoFresh Air Functional Parameter to OPEN and ensure that the setpoint is above 30°F (- 1.0°C). The AutoFresh air relay coil will be grounded by 1-2MSM-24 and power will be provided from 1-2MSM-18. Check ground from 1-2MSM-24 through SP-45 to the AFAR - connection. Check power from 1-2MSM-18. Reset AutoFresh Air Functional Parameter and setpoint as required following testing. If ground or power not good, check connectors and wiring between terminals for damage, moisture or corrosion.