Amana AMVC960803BN Error Code EC5: Accessory Relay Module Missing
What Does Code EC5 Mean?
Error code EC5 on the Amana AMVC960803BN indicates that the integrated control module expects an external accessory relay module to be present on the ComfortNet network but is not detecting it. The accessory relay module is a separate component that provides control relay outputs for accessories such as a whole-house humidifier, energy recovery ventilator, or other HVAC accessories integrated into the system.
Like EC4 (equipment relay module missing), EC5 appears when the system configuration expects this module but it cannot be found — either because the module has failed and dropped off the network, because it was disconnected or removed, or because a wiring problem is preventing communication. It may also appear if a prior technician configured the system to expect this module but it was never installed.
A technician will confirm the system's intended configuration, inspect the accessory relay module's wiring and power supply, and either restore its connection or replace the module. If the accessories controlled by this module are important to the homeowner, timely repair is recommended.
Common Causes
| Cause | Likelihood | DIY? |
|---|---|---|
| Accessory relay module not installed or disconnected | Most common | ✗ Call a pro → |
| Faulty accessory relay module | Common | ✗ Call a pro → |
When to Call a Professional
Contact a licensed HVAC technician if:
- EC5 is present — a technician must confirm the expected system configuration and verify whether the accessory relay module is installed, connected, and powered
- The accessory relay module has failed — replacement and reconfiguration requires professional service
Sources
✓ Verified against manufacturer service manual — March 2026