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Rough fieldstone walls and walnut racking full of bottles in a home wine cellar, a through-the-wall cooling unit's grille set high on the far wall just under the ceiling, and a hand holding a slim probe thermometer in the cold air leaving it.

Common problems

Why the cellar will not hold 55°F: the room, the exhaust side or the unit

A wine cellar cooling unit not cooling is often a unit that works but cannot keep up: the exhaust side breathes air above about 85°F, the door leaks, the room lacks a vapor barrier, or the unit was undersized. Compare the air at both grilles first, then check the exhaust space, the seals and the coils.

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  • What the room and the unit are telling you
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At a
glance.

A cellar drifting up from 55°F into the low 60s rarely does it overnight, and the cause sits as often in the walls, the door or the next room as in the machine. This guide separates a wine cellar cooling unit not cooling from one that cools well but is losing the fight.

Read the whole guide

Exhaust-side limit on many through-the-wall unitsAbout 85°F intake air

WhisperKool and CellarCool rate their self-contained units to hold 55°F only up to this figure.

Proof the coil is coolingA drop of 6°F or more

Breezaire's test: air leaving the cold side against the air entering it.

Normal run time once settledUp to about 75% of the time

CellarPro's figure; a freshly loaded cellar can keep its unit running for up to a week.

Mounting heightWithin 18 inches of the ceiling

WhisperKool's rule, so the unit draws the warmest air in the room first.

First settle whether the unit cools at all

The quickest split takes two minutes and a probe thermometer. Breezaire's instructions ask owners to check the upper part of the warm-side exhaust grille: warm air leaving it means the refrigeration circuit is moving heat. Then compare the air entering the lower grille on the cellar side with the air leaving the upper one. A drop of 6°F or more means the unit itself is doing its job.

CellarPro gives a similar yardstick for its 1800 series, whose discharge at the bottom should run roughly 10°F colder than the number on the display. If the air coming out is barely cooler than the air going in, the trouble is inside the unit. If the drop is healthy and the cellar still drifts upward, heat is getting in faster than a sound unit can pump it out, and the rest of this guide is about finding where.

  • Cold air out, warm air on the exhaust side, cellar still warm: look at the room, the door and the exhaust space.
  • Fans turning, almost no difference between intake and discharge: the compressor, its start parts or the refrigerant charge.
  • Nothing moving at all: the power and controller checks come before anything else.
  • White frost or ice behind the cellar-side grille: read the icing guide, because a blocked coil moves very little heat.

Source: Breezaire — WKL Series installation instructions — Warm air at the exhaust grille and air leaving the cold side 6°F or more colder than it enters mean the unit works; unventilated laundry rooms, closets, bathrooms, garages, crawl spaces, attics and humid basements are poor exhaust locations; dark-room and paper tests reveal air leaks; new building materials release moisture; clean the condenser every 3 months; lowering the set point does not help a cellar that is not reaching it; do not change the setting for 3 days after start-up; CellarPro — 1800 series owner's manual — Discharge about 10°F colder than the display; exhaust space at least as large as the cellar unless ducted; check ducts for kinks and remove louvered grilles when the unit runs constantly; glass is at most R-3; capacity table by cellar size, insulation and ambient temperature; continuous running for up to a week after loading, then up to 75% run time

The exhaust side decides what the cellar can reach

A self-contained unit is a heat pump with its hot half in another room. WhisperKool and CellarCool both state that their through-the-wall units hold 55°F only while the air feeding the condenser stays at or below 85°F. In a storage room under a hot roof, a garage or a closet with its door kept shut, that limit is passed by early afternoon in July, and the cellar warms at the same hour every day.

Size matters on that side too. CellarPro wants the exhaust space to be no smaller than the cellar unless the unit is ducted, and Breezaire rules out garages, attics, crawl spaces, damp basements, and any closet, laundry or bathroom without ventilation as places to dump that air. A unit that breathes its own discharge runs hotter and hotter on the warm side, and the cellar pays for it.

Through-the-wall and ducted units

Stand in the exhaust room with the unit running and look at what the grille faces: boxes stacked within a few feet, a louvered door fitted after the build, a cabinet built around the housing. WhisperKool wants about 3 feet of open air in every direction on that side and warns against recessing the unit or hiding it behind an aftermarket grille. On a ducted unit, a crushed flexible duct above a ceiling or a louvered cover at the far end does the same damage out of sight; CellarPro's first steps for a unit that never stops include checking the ducts for kinks and removing louvered grilles.

Split systems and ceiling-mounted units

A split system moves the condenser outdoors or to a mechanical room, which raises the exhaust limit a long way; WhisperKool rates its Platinum split series to hold 55°F with ambient air up to 120°F. The weak points move with it: a condenser smothered by shrubs or leaves, a line set crossing a hot attic with its insulation torn, an outdoor unit that no longer starts. Ceiling-mounted evaporators add one more, a supply louver aimed into a rack face or a beam, which leaves the far corner several degrees warmer than the spot the sensor sees.

Source: Breezaire — WKL Series installation instructions — Warm air at the exhaust grille and air leaving the cold side 6°F or more colder than it enters mean the unit works; unventilated laundry rooms, closets, bathrooms, garages, crawl spaces, attics and humid basements are poor exhaust locations; dark-room and paper tests reveal air leaks; new building materials release moisture; clean the condenser every 3 months; lowering the set point does not help a cellar that is not reaching it; do not change the setting for 3 days after start-up; CellarPro — 1800 series owner's manual — Discharge about 10°F colder than the display; exhaust space at least as large as the cellar unless ducted; check ducts for kinks and remove louvered grilles when the unit runs constantly; glass is at most R-3; capacity table by cellar size, insulation and ambient temperature; continuous running for up to a week after loading, then up to 75% run time; WhisperKool — SC Pro series owner's manual — Holds 55°F only with intake air at or below 85°F; 3 feet of clearance around the unit, no recess or aftermarket grille; R-13 minimum, R-19 interior walls, R-30 ceilings and exterior walls, warm-side vapor barrier; stone, concrete and glass call for a larger unit; mount within 18 inches of the ceiling; a vent fan needs a fresh-air inlet; CellarCool — CX series owner's manual — The unit cannot keep the cellar at 55°F when the room it exhausts into exceeds 85°F

Close on a small dial thermometer resting on a wooden cellar rack between unlabeled bottles, the cooling unit grille blurred high on the stone wall behind.
Close on a small dial thermometer resting on a wooden cellar rack between unlabeled bottles, the cooling unit grille blurred high on the stone wall behind.

Heat that comes in through the room

Makers size their units for rooms built to a standard, and the numbers are specific. WhisperKool names R-13 as the minimum insulation, prefers R-19 for interior walls and R-30 for ceilings and exterior walls, and requires unbroken plastic sheeting as a vapor barrier on the side facing the house. CellarPro points out that glass panels, windows and doors reach R-3 at best, so a glazed wall or door gives the cellar a far larger heat load than its floor area suggests.

Breezaire describes two free tests for air leaks. Switch off the cellar light from inside, give your eyes a minute, and watch for daylight or lamplight creeping past the door, the unit or any fixture. Then shut a single sheet of paper in the door and tug it: paper that slips free means warm, damp air has the same way in.

  • A door missing weather stripping along any edge, or missing its bottom sweep.
  • Recessed can lights, which draw warm air in from the ceiling cavity.
  • A newly finished room: fresh concrete, lumber and paint give off moisture for months, and the unit spends its effort removing it.
  • Afternoon sun on a glass wall or on the outer face of a cellar wall.

Source: Breezaire — WKL Series installation instructions — Warm air at the exhaust grille and air leaving the cold side 6°F or more colder than it enters mean the unit works; unventilated laundry rooms, closets, bathrooms, garages, crawl spaces, attics and humid basements are poor exhaust locations; dark-room and paper tests reveal air leaks; new building materials release moisture; clean the condenser every 3 months; lowering the set point does not help a cellar that is not reaching it; do not change the setting for 3 days after start-up; CellarPro — 1800 series owner's manual — Discharge about 10°F colder than the display; exhaust space at least as large as the cellar unless ducted; check ducts for kinks and remove louvered grilles when the unit runs constantly; glass is at most R-3; capacity table by cellar size, insulation and ambient temperature; continuous running for up to a week after loading, then up to 75% run time; WhisperKool — SC Pro series owner's manual — Holds 55°F only with intake air at or below 85°F; 3 feet of clearance around the unit, no recess or aftermarket grille; R-13 minimum, R-19 interior walls, R-30 ceilings and exterior walls, warm-side vapor barrier; stone, concrete and glass call for a larger unit; mount within 18 inches of the ceiling; a vent fan needs a fresh-air inlet

When the unit itself falls short

Once the room checks out, a short list of mechanical causes remains. A dusty condenser coil is the most common and the easiest to correct; Breezaire's schedule is a look and a vacuum every three months, from the exhaust side. A condenser or evaporator fan that no longer spins, a compressor that hums, overheats and cuts out on its overload, and a slow refrigerant leak all produce the same warm cellar with different sounds. A leak is never an owner's top-up job: EPA's Section 608 program certifies the technicians who open refrigerant circuits, and a recharge without a repair lasts weeks.

A unit that was always too small

Some cellars never held 55°F through their first summer. WhisperKool treats an undersized unit as a cause in its own right and warns that stone, concrete and glass look solid but insulate poorly. CellarPro's capacity table for its 1800 series shows how thin the margins are: its smallest model handles a 100-cubic-foot cellar insulated to R-19 with 85°F air around it, but not the same room at 95°F, and a 300-cubic-foot cellar at 85°F with R-12 walls is beyond every model in the series while the same room at R-19 is not. If the trouble began the week the racks were filled, sizing belongs on the list before any part.

A unit mounted too low on the wall

Cold air sinks and warm air pools under the ceiling. WhisperKool wants its through-the-wall units within 18 inches of the ceiling so they draw that warm layer first, and lists a low mounting as a direct cause of a warm cellar. A unit set halfway down a wall leaves the top rows of racking sitting in air it never reaches, and the top rows can run warmer than whatever the sensor reports.

Source: Breezaire — WKL Series installation instructions — Warm air at the exhaust grille and air leaving the cold side 6°F or more colder than it enters mean the unit works; unventilated laundry rooms, closets, bathrooms, garages, crawl spaces, attics and humid basements are poor exhaust locations; dark-room and paper tests reveal air leaks; new building materials release moisture; clean the condenser every 3 months; lowering the set point does not help a cellar that is not reaching it; do not change the setting for 3 days after start-up; US EPA — Section 608 technician certification — Technicians who service equipment that could release refrigerant are certified under Section 608 of the Clean Air Act

A couple lifting a bottle from a lit stone-walled wine cellar, the cooling unit's grille high on the far wall
For the heart of your home.

Questions
owners ask.

Will turning the setpoint down cool the cellar faster?
No. Breezaire states plainly that lowering the set point will not help a cellar that is not reaching the current one. The setting only tells the controller where to stop, so a colder number keeps an overloaded unit running longer and pulls more moisture onto the coil.
Why is the cellar fine in winter and warm every summer?
That pattern points at the exhaust side or the building rather than a worn part. The room the unit exhausts into warms with the season, capacity falls as it does, and a unit chosen with no margin runs out of headroom in the hottest weeks. Measure the exhaust room on a hot afternoon before blaming the machine.
How long should a newly loaded cellar take to reach 55°F?
Longer than most owners expect. CellarPro says a unit can run continuously for up to a week after bottles are first loaded, and Breezaire asks owners to leave the setting alone for at least three days after start-up. The air reaches the setting days before the wine does.
Can a fan in the exhaust room solve it?
Sometimes. WhisperKool suggests a vent fan where the exhaust area overheats, but adds that the room also needs a fresh-air inlet, or the fan only stirs the same warm air. CellarPro likewise lists more cool air at the condenser side among the remedies for a unit that never stops.

The problems
behind it.

Each has a page of its own: what it usually means and the causes in the order worth checking.

All 17 problems
A small stone-walled wine cellar with dark wooden racks full of unlabeled bottles lying on their sides, a through-the-wall cooling unit grille set high on the far wall and a round dial thermometer standing in a glass of water on a tasting shelf in front. The collection is exposed

Wine Cellar Too Warm

6 causes, cheapest first

 A ducted wine cellar with a white supply grille in the wood-paneled ceiling above tall racks of unlabeled bottles, a small wall clock with a plain face on the end panel and a faint shimmer of cool air below the grille. Problem

Cellar Cooling Unit Running Constantly

5 causes, cheapest first

 A narrow storage closet with its door wide open, the louvered exhaust grille of a through-the-wall cellar cooling unit set into its back wall, stacked cardboard boxes pressed close in front of the grille and a faint heat shimmer in the air. Problem

Cellar Cooling Unit Exhaust Overheating

5 causes, cheapest first

 A ceiling-mounted cellar cooling unit set into the wooden ceiling of a wine cellar, its slotted grille seen from below with a still fan blade visible in the shadow behind, rows of unlabeled bottles in racks along the walls below it. Problem

Cellar Cooling Unit Fan Not Running

4 causes, cheapest first

When it needs
a technician.

The repairs on the right are where this guide ends when the checks do not settle it.

Wine cellar cooling diagnostic visit

A visit that reads the cellar, the room the heat goes to and the cooling unit itself, and ends with one named cause, whether it is a part or the room.

Cellar cooling load and room check

Measuring the cellar as the cooling unit sees it: insulation, vapor barrier, door, glass and the heat load, to show whether the unit can ever keep up.

Cellar compressor and sealed system repair

Getting the heart of the cellar unit pumping again, from the start capacitor, relay and contactor that give out first to a compressor or a sealed-system restriction.

Cellar evaporator and condenser fan repair

Restoring the two fans a cellar unit depends on: the one that moves cellar air across the cold coil and the one that throws the heat away.

More in
common problems.

What it means when the cellar will not come down to 55°F, water runs down the wall below the unit, the evaporator turns white with ice, or the cooling never seems to rest.

The whole section
What the room and the unit are telling you

Why the cellar unit drips water, and which side of the wall it lands on

Water on the cellar floor, down the exhaust-side wall or from a ceiling unit points to different parts of the drain path, and much of it starts with humid air leaking into the room.

 What the room and the unit are telling you

Why the evaporator ices over, and what the ice pattern reveals

Frost that clears in a defrost cycle is routine; ice that stays points to airflow, a cold exhaust room or a low charge, and how far it climbs the coil helps say which.

 Guides

All 18 guides

Six sections, by what you are trying to find out.

Back to your everyday

Read it and still not sure?

Book with what you checked and the model number, and the technician starts where the guide stopped.

Schedule a repair Call (844) 398-5977
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