Red LED 1 flash Red communications LED 1 flash - communication failure

What the control is telling you

The furnace control lost communication on the ComfortNet network.

Applies to: GMVC95/AMVC95 upflow and *CVC9 counterflow two-stage furnaces

Likely causes

• Communication failure on the data lines
• Bias / termination dip switches set wrong

Test and repair steps

1. Press the learn button once quickly for a power-up reset.
2. Check the bus BIAS and TERM dip switches are all ON.
3. If a quick press does not clear it, hold the learn button for roughly 2 s (full factory-style network reset).

Settings for these units

• Normal status displays (7-segment) · Goodman/Amana GM9S96/AM9S96
• Normal status displays (7-segment) · Goodman/Amana GM9S80/AM9S80
• Normal status displays (7-segment) · Goodman/Amana GM9C96/AM9C96
• Minimum recommended filter size · Goodman/Amana GM9C96/AM9C96

Models that show this code

10 models in Goodman/Amana *MVC95/*CVC9 two-stage ComfortNet

Other codes on the same units

• F Continuous fan
• HI High-stage heat
• OP Normal - waiting for a call
• Red LED 2 flashes Red communications LED 2 flashes - reset in progress
• Red LED off Red communications LED off - normal
• Rx LED 1 steady flash Green receive LED single steady flash - no network found
• Rx LED off Green receive LED off - no power or communications error
• Rx LED on solid Green receive LED on solid - data lines miswired or shorted