FA-92683 / HVAC thermostat control / Member archive

Low-pressure switch trips the compressor during startup · case 03

In cold weather the unit soft-locks on every start because suction pressure is briefly low.

Member previewVariant 3 · 3 implementations · 8 checks per implementation

Case contract

Compressor pressure-switch lockout per minute; samples are [call, hp_ok, lp_ok] where call may also be "reset". While running, an open high-pressure switch trips at once; the low-pressure switch is ignored for the first 2 minutes after start. A trip enters a 5-minute soft lockout, after which the unit retries automatically if still called. The third trip within a sliding 60-minute window (trips older than 60 minutes are forgotten) causes a hard lockout that only reset clears; reset also clears the trip history. Return run, idle, soft or hard per minute.

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: scenario 2	["run", "run", "idle", "run", "run", "idle", "run", "run", "idle", "idle", "run", "soft", "soft", "soft", "soft", "soft", "run", "idle", "idle", "run", "run", "run", "soft", "soft", "soft", "soft", "soft", "idle", "run", "run", "run", "idle", "run", "idle", "run", "soft", "soft", "soft", "soft", "soft", "idle", "idle", "run", "run", "soft", "soft", "soft", "soft", "soft", "run", "hard", "hard", "hard", "hard", "hard", "hard", "hard", "hard", "hard", "hard", "hard", "hard", "hard", "hard", "hard", "hard"]	["run", "run", "idle", "run", "run", "idle", "run", "run", "idle", "idle", "run", "soft", "soft", "soft", "soft", "soft", "run", "idle", "idle", "run", "run", "run", "soft", "soft", "soft", "soft", "soft", "idle", "run", "run", "run", "idle", "run", "idle", "run", "run", "soft", "soft", "soft", "soft", "soft", "idle", "run", "run", "soft", "soft", "soft", "soft", "soft", "run", "run", "hard", "hard", "hard", "hard", "hard", "hard", "hard", "hard", "hard", "hard", "hard", "hard", "hard", "hard", "hard"]	Failed

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