Indoor Fan Blowing but Outdoor Silent: Faulty Starter Relay

The indoor fan runs and the outdoor unit stays silent. A seized compressor is assumed, though nothing has reached it yet.

By Team Snowflake | Updated 24 Aug 2026

Teaching case based on recurring Snowflake service patterns; identifying details are combined.

How this presents

Indoor fan blowing, room staying warm, and nothing at all from outside. No hum, no fan, no click. The system behaves as though the outdoor half has been unplugged, which is exactly what makes it read as terminal.

Setup: Daikin Wall-mounted10-12 yearsHDBPunggol
Misread as: A seized compressor, and a quote to replace the whole outdoor unit.
Check first: The start path in order, from the indoor command to the compressor terminals

What else produces this

Silence outdoors is a symptom of the start path, not of any one component in it. Between the indoor call for cooling and the compressor terminals sits a communication link, an incoming supply, a relay and a set of contacts, and a failure anywhere along that chain produces the same nothing. Working it in order costs minutes and settles which link.

An indoor unit sending the start command, with the communication link testing normal, moves the fault outdoors.
Incoming power present at the outdoor connection removes the supply from the list.
A relay that clicks in on command but shows pitted and burnt contacts is moving without conducting.
No power at the compressor terminals despite the relay closing locates the break, and a compressor testing healthy confirms it is waiting rather than failed.

Why it happens

The relay closes a set of contacts every time the system calls for cooling, and each closure costs a little of the contact face. After years of switching, the faces are pitted enough that the relay still moves and no longer conducts. That is the shape of the fault: everything looks like it is working, and no current arrives. From outside there is nothing to hear, because nothing downstream ever gets the chance to run.

What resolution involves

A matching relay, and a check that power now reaches the compressor terminals rather than merely that the unit started. Starting on the first command is encouraging and not proof, because a marginal contact starts too. What follows is a full cycle to confirm the refrigerant circuit came back cleanly after the idle period.

How to tell it worked

Power at the terminals, not just a unit that started. Ask what was measured after the part went in, because a worn contact can still start a compressor on a good day and fail on a hot one.

Before you approve a quote

A silent outdoor unit is a power question, not a compressor one

The compressor runs only when mains power reaches it. Several cheap parts sit between the command and the terminals.
Ask whether the start path was traced before a compressor was quoted. The relay, the wiring and the supply take minutes to check.
A quote for the whole outdoor unit on a silent symptom is worth a second opinion.

Questions this case answers

Indoor fan blowing but outdoor unit silent: what does that mean?

That the outdoor half is not receiving, or not passing on, the instruction to run. The indoor fan works off its own supply, so it will happily blow warm air while nothing outside moves. Silence is a start-path symptom, and the compressor is only the last item on that path.

What is a starter relay and how does it fail?

It is the switch that feeds mains power to the compressor when cooling is called for. It fails by wear: every closure costs a little of the contact face, and after years of switching the faces pit until they no longer conduct. The relay still moves, which is what makes it deceptive.

Is a silent outdoor unit always a seized compressor?

No, and that is the point of checking in order. A dead compressor usually announces itself by trying. There is a hum, a buzz, or a trip. Complete silence more often means the instruction or the power never arrived, and both are cheaper problems.

Can a relay be replaced without touching the compressor?

Yes. It is a separate component in the outdoor unit, and swapping it does not disturb the sealed refrigerant circuit at all. That is why it is worth clearing before anyone prices work that does.

Ready to get started?

Tell us what’s going on. Symptoms, setup, photos, anything we should know. We’ll assess and come back with the right next step.

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