SubZero Refrigerator Freezer Error Code 86 – How to fix? by KatyApplianceRepair.com  

Sub-Zero error code EC 86 indicates
a communications failure between the compressor and main board. Below is a quick reference
and troubleshooting guide for this code.

Quick Reference

Error Code	Meaning	Severity
EC 86	Communications failure — wiring fault between the variable-speed compressor and the main control board	High

Cause & Solution

Cause	What to Check	Fix
Damaged or disconnected communication cable	Inspect the multi-pin connector between the compressor inverter and main board	Re-seat or replace the communication cable
Faulty compressor inverter board	Test communication signal with a multimeter at the connector pins	Replace the inverter board if no signal is detected