FA-92778 / HVAC thermostat control / Member archive

Reversing valve terminal type is inverted · case 03

An O-type heat pump blows cold air on a heating call.

Member previewVariant 3 · 3 implementations · 8 checks per implementation

Case contract

Heat pump reversing valve output (O/B terminal) and compressor per sample; samples are the call (heat, cool or None). An O-type valve is energized for cooling, a B-type for heating. The valve is de-energized at power-up and holds its last position while idle. On a sample where the valve changes position the compressor waits (off) for pressure equalization. Return [compressor, valve_energized].

Why this case matters

Residential and light-commercial thermostats make these decisions sample by sample; each defect changes equipment calls in a way that shows up as short cycling, comfort complaints or equipment stress.

One recorded failure

Sample boundary fixture

This sample comes from the broken implementation of a controlled reproducer.

Boundary fixture	Actual	Expected	Outcome
regression: first call heat on O	`[[false, true], [true, true], [false, true], [false, false]]`	`[[true, false], [true, false], [false, false], [false, true]]`	Failed

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