CHK AFA Solenoid Circuit
electrical
Description
AutoFresh Air Exchange relay coil circuit is shorted when energized or open at other times; the unit gives alarm only.
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 PCM. Verify there is no damage to relay, and no damaged or corroded connections. b. Check resistance of coil (terminals 1 and 2). Refer to Section 1.11 for specifications. 2. Check Power and Wiring a. Check for power at fuse F10 terminal A inside PCM. Must have minimum 11 VDC. If not, check PCM circuit and fuse F5. b. Check fuses F5 and F10. Verify correct fuse, see Figure 1.7. c. Check for power at AFAR + terminal. Replace PCM. d. Set the AutoFresh Air Functional Parameter to OPEN and ensure the set point is above 30°F (- 1.0°C). The AutoFresh air relay coil will be grounded by the main microprocessor at 3MM-13. Check ground from 3MM-13 through PCM-26 to the AFAR - connection. Reset AutoFresh Air Functional Parameter and setpoint as required following testing. If ground not good, check connectors and wiring between terminals for damage, moisture or corrosion.