Goodman furnace d2: Dehumidification, high stage cooling, communicating mode

d2 means the system is removing humidity while cooling on the compressor's high stage. Normal operation, and the mode used when both heat and humidity need dealing with at once.

Applies to: Goodman GMVM97, GCVM97 and Amana AMVM97 modulating gas furnaces with a two-character display, on a communicating system with a two stage compressor.

What it means

This is dehumidification with full cooling capacity. The control uses it when the cooling load is high enough that low stage cannot keep up, but humidity still needs managing — a hot, humid afternoon rather than a mild damp one. Blower speed is still reduced relative to straight cooling, so the air coming from the registers is colder and there is less of it. Someone who checks the display on the hottest day of the year and sees an unfamiliar two character code is looking at the system working at full capacity, not failing.

Most common causes

A communicating thermostat calling for cooling and dehumidification with the compressor on high stage.
A high cooling load combined with high humidity.
The system stepping up from d1 because low stage could not satisfy the call.

How to diagnose it

Note the outdoor conditions. High stage on a hot humid day is correct behaviour.
Air that is colder but lower in volume than usual is the expected result of this mode.
If the system sits in d2 for long periods in mild weather, that is worth investigating — it suggests the equipment is not keeping up, or the humidity setpoint is unrealistic.
Compare against d1, the low stage version of the same mode.

How to fix it

Nothing. This is normal operation at full capacity.
If the system cannot satisfy the thermostat while in this mode, the complaint is capacity or charge, not this code.
Check the humidity setpoint before assuming a fault.

Notes

Reading d1 and d2 over a season is a genuinely useful diagnostic. A system that never reaches d2 is comfortably sized; one that lives in it is not.

All codes for this manufacturer

Goodman and Amana furnace fault codes — every code, with what differs between models.

Sources

Goodman Manufacturing — Diagnostic Code Identification System (model-specific fault code lookup)

This site is a reference, not a substitute for a licensed HVAC technician. Gas appliances can leak carbon monoxide and cause fire. Anything involving gas lines, the heat exchanger, or the flame sensing circuit should be handled by a licensed professional. Pages are written with AI assistance from the sources listed on each page and checked against them before publishing.