---
title: "Unit running constantly"
description: "Sub-Zero unit running constantly — a compressor that runs without stopping, or cycles far more than it used to, while temperatures still look about right."
url: "https://subzeromiami.support/symptoms/unit-running-constantly/"
date_modified: "2026-08-18"
---


# Sub-Zero unit running constantly

### The fastest diagnosis is the code

A fan or load code here saves a lot of measuring. If the display has one, it usually names the reason the unit cannot stop running.

### Why it matters before temperatures change

A unit that never cycles off is working at the limit of what it can do. It is holding temperature today; it is doing so by running continuously, and that is the state in which compressors age fastest. Catching it here is the difference between a condenser service and a sealed system repair.

### What is usually behind it

- A condenser that cannot shed heat — dust inland, salt corrosion near the water
- A fan out of range, so airflow across the coil has dropped
- Door seals letting warm air in continuously
- Ambient heat: a unit in a hot kitchen or an outdoor enclosure in August

Never cycling off

What it usually means

Runs all day, temperatures still fine

Warmer kitchen than it used to be

Higher electricity bill with no other change

The fastest diagnosis is the code

A fan or load code here saves a lot of measuring. If the display has one, it usually names the reason the unit cannot stop running.

Why it matters before temperatures change

A unit that never cycles off is working at the limit of what it can do. It is holding temperature today; it is doing so by running continuously, and that is the state in which compressors age fastest. Catching it here is the difference between a condenser service and a sealed system repair.

What is usually behind it

A condenser that cannot shed heat — dust inland, salt corrosion near the water

A fan out of range, so airflow across the coil has dropped

Door seals letting warm air in continuously

Ambient heat: a unit in a hot kitchen or an outdoor enclosure in August

A condenser that cannot shed heat

Dust inland, salt corrosion near the water. Look through the grille — this is the cause behind more continuous running than everything else here put together.

A fan out of range

Airflow across the coil has dropped, so the system runs longer to do the same work. It often shows as a change in sound before anything else.

Door seals letting warm air in

Continuously, which is why the unit never gets to stop. Check the seal along its whole length rather than at the handle.

The room itself

A unit in a hot kitchen or an outdoor enclosure in August is being asked for more than it was designed to give. Worth knowing before anything is replaced.

Weeks of it, unnoticed

A unit that never cycles off is holding temperature by running continuously, and that is the state in which compressors age fastest. Catching it here is the difference between a condenser service and a sealed system repair.

Look at the condenser through the grille

Dust inland, salt corrosion near the water. This is behind more continuous running than everything else put together, and you can see it without tools.

Check whether the room itself is hotter

A unit in a hot kitchen or an outdoor enclosure in August is being asked for more than it was built to give. Worth knowing before anything is replaced.

Check the seals along their whole length

Not just at the handle. A door letting warm air in continuously is why the unit never gets to stop.

Then book the visit

Say how long it has been running without cycling off. Weeks of it is the difference between a condenser service and a sealed system repair, and that is why it is worth saying.

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**[Read full article: Unit running constantly](https://subzeromiami.support/symptoms/unit-running-constantly/)**