Why is there ice on your aircon pipe?

Ice on aircon copper pipe: what it tells you

Frost or ice on the copper pipe or the indoor coil tells you one thing: the coil is colder than it should be. You may also notice weaker cooling, or water dripping from the indoor unit once the ice starts to melt.

An aircon pipe frozen over is a sign of a problem, not the problem itself, so the next step is to work out why. Common causes include:

• Too little airflow over the coil, from dirty filters or a blocked air intake.
• A low refrigerant charge, which points to a refrigerant leak.
• A fan that is not running properly.
• A very low temperature setting used for long hours.

These are common causes, not a diagnosis. You can check the filters, the space around the unit and the setting yourself. A refrigerant leak or a fan fault needs a technician.

Ice and weak cooling often turn up together. If the room stays warm after the ice has cleared, the aircon not cold guide walks through the other checks.

Switch off and let it thaw

The first step is simple: switch the cooling off and let the ice melt on its own. Running a frozen unit strains it.

EMA says electrical work in an HDB flat needs a Licensed Electrician, the class of LEW approved for loads of up to 45kVA. See EMA's page on engaging licensed electrical workers.

Lay a towel or a tray under the indoor unit, because the melt water can drip onto the wall, floor or furniture below. Give aircon indoor unit ice time to melt on its own.

Never chip, scrape or heat the ice to speed things up: the thin fins and copper pipes bend and dent easily.

Once the coil and pipe are dry, run the aircon again on a normal setting and watch whether the ice returns. Note when it comes back and which unit it is on, as this helps a technician later.

If water keeps dripping once the ice has gone, the aircon leaking water page covers what to check next.

Check the filters and airflow first

With the ice gone, look at airflow first, as it is the cause you can check and fix yourself. Dirty filters cut the air passing over the coil.

On its troubleshooting page, Daikin says that if the air filter in the indoor unit is dirty, it can lead to condensate forming which will leak from the air outlet. For its own units, Daikin recommends cleaning the air filters every 2 weeks, and says to wash the filters with water or clean them with a vacuum cleaner.

The National Environment Agency (NEA) gives similar advice in its energy saving tips: check the air-conditioner air filter once a month and clean or replace it when necessary, so that it will run efficiently.

HDB's home care guide for air-conditioners also says to clean the air filters to maintain optimal airflow.

If the filters look grey or clogged, clean them before you run the aircon again. For a simple method, see how to clean an aircon filter.

When ice points to a refrigerant leak

If the filters are clean, the air flows freely and the ice still comes back, a low refrigerant charge is one possible cause. A low charge points to a refrigerant leak, and that needs a trained technician with the right equipment to find and fix.

Before you book, rule out the simpler causes. If you usually run the aircon on a very low setting for long hours, try a normal setting for a few days and see whether the ice still forms. If it does, and the filters are clean, an aircon freezing up again and again is worth a proper check rather than another round of thawing.

A technician can check whether the charge is low, look for the refrigerant leak and see whether the fan is running properly. The aircon gas leak signs guide lists the other signs to look for, so you can tell the technician what you have noticed.

Getting it checked and keeping it running well

Regular care makes it less likely that the ice comes back. NEA's energy saving tips say to service air-conditioning units regularly and get them inspected annually.

HDB's air-conditioners page says regular maintenance of the condensing unit helps prolong its lifespan and keep it running efficiently, and to have it serviced regularly by a licensed service provider. HDB also asks you to look out for any signs of leaking: the condensation water should discharge into a nearby internal floor trap.

When you book a check, tell the technician when the ice appears, which unit it is on, the setting you used and when the filters were last cleaned. To find a company for the job, see the aircon repair page. Cost depends on the job, so ask what the visit covers before you confirm.

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