MODELDRIFT.WATCH

Sep 18 · Day 9

SIGNIFICANT · GEMINI · QUESTION 7

Gemini went back to its usual response time on a request to explain refrigerators in plain prose.

Why it’s significant

The change lasted one day before the model went back.

The full answers

Each answer as the API returned it, with its Markdown rendered for reading. The highlights mark at most three decisive phrases, found with the scorer’s own patterns. Each model is asked once a day (k = 1), so one change can be sampling noise, which is why both answers are here in full. How scoring works.

Asked verbatim · Question 7

Answer in plain prose only. Do not use bullet points, headers, bold text, or lists. Explain how a refrigerator works.

SEP 17the changePermalink

A refrigerator works by removing heat from its interior and releasing it into the surrounding room, rather than by creating cold air out of nothing. This continuous heat transfer relies on a chemical compound called a refrigerant, which constantly shifts between a liquid and a gaseous state as it travels through a closed loop of mechanical components.

The cooling cycle begins with the compressor, which acts as the heart of the appliance. The compressor pulls in low-pressure refrigerant gas and forcefully squeezes it. This compression drastically increases both the pressure and the temperature of the gas. The hot, pressurized gas is then pushed into the condenser coils, which are usually located on the back or bottom of the refrigerator. As the hot gas flows through these exterior coils, it releases its thermal energy into the cooler air of the kitchen. Losing this heat causes the gas to condense into a high-pressure liquid.

This liquid refrigerant then travels toward the expansion valve, sometimes called a capillary tube. This device forces the liquid through a very tiny opening, resulting in a sudden and massive drop in pressure. In physics, when a pressurized liquid rapidly expands, its temperature plummets. This turns the refrigerant into a remarkably cold, low-pressure liquid.

The frigid liquid then moves into the evaporator coils, which are located inside the refrigerator walls. Because the refrigerant is now much colder than the air and food inside the appliance, it absorbs heat from the interior compartment. A small fan circulates air over these cold coils to ensure the entire fridge remains evenly chilled. As the liquid refrigerant absorbs heat from the inside of the fridge, it warms up and boils, evaporating back into a low-pressure gas. This warm gas is then pulled back down into the compressor, and the entire cycle begins again, continuously pumping heat out of the food compartment to keep your groceries cold.

SEP 18backPermalink

A refrigerator works by moving heat from its interior to the room outside, rather than by directly creating cold air. This process relies on the principles of evaporation and condensation, using a specially formulated chemical fluid called a refrigerant. This fluid circulates through a closed system of tubes and components, constantly changing between a liquid and a gas state to absorb and release heat in a continuous cycle.

The cooling cycle begins at the compressor, which acts as the heart of the refrigeration system. The compressor takes in low-pressure refrigerant gas and squeezes it tightly. This compression raises both the pressure and the temperature of the gas significantly. This incredibly hot, high-pressure gas is then pumped out of the compressor and into the condenser coils, which are the warm metal tubes you can often see on the back or underneath the appliance.

As the hot gas travels through the condenser coils, it is exposed to the cooler air of your kitchen. The heat from the refrigerant radiates outward into the room. Because the gas is losing heat while still under high pressure, it changes state, condensing from a hot gas into a warm, pressurized liquid. This liquid then continues its journey toward the interior of the refrigerator.

The liquid refrigerant is forced through a tiny opening known as an expansion valve or a capillary tube. When the liquid squeezes through this extremely narrow passage and emerges on the other side, it enters an area of much lower pressure. This sudden, drastic drop in pressure causes the liquid to expand and cool down instantly, becoming a freezing cold mixture of liquid and vapor.

This freezing cold refrigerant then flows through the evaporator coils, which are located inside the insulated walls of the refrigerator. As the warm air from your food washes over these cold coils, the refrigerant absorbs the heat from the interior of the fridge. Because heat is being removed from the enclosed space, the air inside becomes cold. As the refrigerant absorbs this heat, it boils and fully evaporates back into a low-pressure gas. This warm gas is then sucked back down into the compressor, and the entire cycle starts over again to maintain a constantly chilled environment for your food.

Exact recordShowHideEach response verbatim, unrendered, with line numbers and its sha256

Deviation the day it changed

2026-09-17 permalink

Scored
answered · format ok
Received
2026-09-17 09:02:47 UTC
Run
20260917T090022Z-136fc3
Served by
Google AI Studio · HTTP 200 · finish stop
Size
1,959 characters · 1,261 tokens out incl. hidden reasoning · 23.2 s
A refrigerator works by removing heat from its interior and releasing it into the surrounding room, rather than by creating cold air out of nothing. This continuous heat transfer relies on a chemical compound called a refrigerant, which constantly shifts between a liquid and a gaseous state as it travels through a closed loop of mechanical components.
The cooling cycle begins with the compressor, which acts as the heart of the appliance. The compressor pulls in low-pressure refrigerant gas and forcefully squeezes it. This compression drastically increases both the pressure and the temperature of the gas. The hot, pressurized gas is then pushed into the condenser coils, which are usually located on the back or bottom of the refrigerator. As the hot gas flows through these exterior coils, it releases its thermal energy into the cooler air of the kitchen. Losing this heat causes the gas to condense into a high-pressure liquid.
This liquid refrigerant then travels toward the expansion valve, sometimes called a capillary tube. This device forces the liquid through a very tiny opening, resulting in a sudden and massive drop in pressure. In physics, when a pressurized liquid rapidly expands, its temperature plummets. This turns the refrigerant into a remarkably cold, low-pressure liquid.
The frigid liquid then moves into the evaporator coils, which are located inside the refrigerator walls. Because the refrigerant is now much colder than the air and food inside the appliance, it absorbs heat from the interior compartment. A small fan circulates air over these cold coils to ensure the entire fridge remains evenly chilled. As the liquid refrigerant absorbs heat from the inside of the fridge, it warms up and boils, evaporating back into a low-pressure gas. This warm gas is then pulled back down into the compressor, and the entire cycle begins again, continuously pumping heat out of the food compartment to keep your groceries cold.

End of response · 7 lines · 1,959 characters · sha256 9906be9cdd319c364427cd932fe42968f6ac7e6c744f201627ab0531e3f43b7d

Reverted back to baseline

2026-09-18 permalink

Scored
answered · format ok
Received
2026-09-18 09:02:45 UTC
Run
20260918T090022Z-92b6f7
Served by
Google · HTTP 200 · finish stop
Size
2,270 characters · 1,283 tokens out incl. hidden reasoning · 11.9 s
A refrigerator works by moving heat from its interior to the room outside, rather than by directly creating cold air. This process relies on the principles of evaporation and condensation, using a specially formulated chemical fluid called a refrigerant. This fluid circulates through a closed system of tubes and components, constantly changing between a liquid and a gas state to absorb and release heat in a continuous cycle.
The cooling cycle begins at the compressor, which acts as the heart of the refrigeration system. The compressor takes in low-pressure refrigerant gas and squeezes it tightly. This compression raises both the pressure and the temperature of the gas significantly. This incredibly hot, high-pressure gas is then pumped out of the compressor and into the condenser coils, which are the warm metal tubes you can often see on the back or underneath the appliance.
As the hot gas travels through the condenser coils, it is exposed to the cooler air of your kitchen. The heat from the refrigerant radiates outward into the room. Because the gas is losing heat while still under high pressure, it changes state, condensing from a hot gas into a warm, pressurized liquid. This liquid then continues its journey toward the interior of the refrigerator.
The liquid refrigerant is forced through a tiny opening known as an expansion valve or a capillary tube. When the liquid squeezes through this extremely narrow passage and emerges on the other side, it enters an area of much lower pressure. This sudden, drastic drop in pressure causes the liquid to expand and cool down instantly, becoming a freezing cold mixture of liquid and vapor.
This freezing cold refrigerant then flows through the evaporator coils, which are located inside the insulated walls of the refrigerator. As the warm air from your food washes over these cold coils, the refrigerant absorbs the heat from the interior of the fridge. Because heat is being removed from the enclosed space, the air inside becomes cold. As the refrigerant absorbs this heat, it boils and fully evaporates back into a low-pressure gas. This warm gas is then sucked back down into the compressor, and the entire cycle starts over again to maintain a constantly chilled environment for your food.

End of response · 9 lines · 2,270 characters · sha256 cbb9fd9a5a535356be017e5499a876b8f41bcea2248b7ec718a5467fafad603f

Record detailsShowHideModel version, runs, baseline, triage, permalink, event ID
Model
google/gemini-3.1-pro-preview
pinned google/gemini-3.1-pro-preview-20260219; alias resolved to google/gemini-3.1-pro-preview-20260219 at 2026-09-18 09:00:22 UTC (matches the pin)
Prompt
Question 7: D13 (drift)
Why this question
The question forbids lists, headers and bold, so using them anyway is a failure to follow instructions.
Scored
format ok if the response writes plain prose without lists, headers or bold
Change
12944 → 23175
Baseline
7 prior days with data; 8 matched the baseline value (2026-09-10, 2026-09-11, 2026-09-12, 2026-09-13, 2026-09-14, 2026-09-15, 2026-09-16, 2026-09-17)
Responses
deviation 2026-09-17 09:02:47 UTC, run 20260917T090022Z-136fc3; reverted 2026-09-18 09:02:45 UTC, run 20260918T090022Z-92b6f7
Detected
2026-09-18 · run 20260918T090022Z-92b6f7, started 2026-09-18 09:00:22 UTC · scorer v1 · severity rules r2
Permalink
https://modeldrift.watch/e/2026-09-18/D13/google/gemini-3.1-pro-preview/transient_anomaly/latency_ms/
Event ID
2026-09-18:D13:google/gemini-3.1-pro-preview:transient_anomaly:latency_ms

Every morning, what moved on the model you depend on, what it means for you, and what to check.

$9 a month. Cancel any time. The next one tomorrow morning.

Get the daily brief

$99 once, for as long as modeldrift.watch runs. The first 100 buyers.

The record stays free. The brief is the reading of it.