Water or Ice Around Unit in Mullan, ID

Here's the reality: a frozen coil or a dripping drain pan isn't just an AC problem. It's a home damage problem.

When ice builds up on the evaporator coil (the indoor coil that absorbs heat from your air), it blocks airflow completely. The system keeps running, but it can't cool anything. Meanwhile, when that ice melts and it will you get a flood inside your home.

The risks stack up quickly:

• Water damage to ceilings, walls, flooring, and subfloor
• Mold and mildew growth inside the air handler and ductwork
• Compressor failure from refrigerant flooding back in liquid form (this is an expensive repair)
• Electrical hazards if water reaches wiring or the air handler's electrical components

The longer the system runs in this state, the more it costs to fix. A clogged drain line caught early is a straightforward repair. A compressor that's been flooded with liquid refrigerant is a different conversation entirely.

The diagram below shows how a frozen evaporator coil develops: warm air enters the air handler, passes over the evaporator coil, and exits as cooled air. When airflow is blocked or refrigerant pressure drops, the coil surface falls below freezing. Ice forms on the coil fins, restricts the airflow path further, and water overflows the drain pan below once the ice begins to melt.

``` ┌─────────────────────────────┐ Warm air in ──► │ EVAPORATOR COIL │ ──► Cooled air out │ (freezes when airflow │ │ or refrigerant is off) │ └──────────┬──────────────────-┘ │ condensate drips ▼ ┌─────────────────────────────┐ │ DRAIN PAN │ │ (overflows when drain line │ │ is clogged) │ └──────────┬──────────────────-┘ │ Condensate drain line ──► out

Refrigerant lines run alongside the coil (suction line + liquid line). Low refrigerant pressure causes the coil surface to drop below 32 °F. ```

This is where most pages give you a one-liner. We're going to explain the actual mechanics, because understanding the cause helps you make a better decision.

1. Restricted Airflow Across the Evaporator Coil

Your evaporator coil works by absorbing heat from warm air passing over it. That heat transfer keeps the coil from dropping below freezing. When airflow is restricted by a clogged filter, a collapsed duct, or a dirty coil the coil gets too cold and freezes.

In Mullan's older housing stock, this is a common story. Homes built during the area's earlier construction periods often have builder-grade equipment that's now 15 or more years old. Those units weren't designed to last forever, and the air handlers in particular accumulate years of dust, debris, and neglect. A coil that's never been cleaned is a coil that's working toward a freeze-up.

2. Low Refrigerant (Refrigerant Leak)

Refrigerant doesn't get "used up" it circulates in a closed loop. If your system is low on refrigerant, there's a leak somewhere.

When refrigerant pressure drops, the evaporator coil gets colder than it should. Ice forms. The system loses cooling capacity. You might notice weak or warm air before you ever see the ice.

Low refrigerant is not a top-off situation. The leak needs to be found and repaired first. Otherwise you're just refilling a punctured tire.

3. Clogged Condensate Drain Line

Your AC pulls humidity out of the air as it cools. That moisture drips off the evaporator coil into a drain pan, then exits through a condensate drain line. When that line clogs algae, debris, and mineral buildup are the usual culprits water backs up into the pan and overflows.

This is one of the most common causes of water pooling near the indoor unit. It's also one of the most preventable with regular maintenance.

4. Dirty or Frozen Evaporator Coil

A coil caked with dust and grime can't transfer heat efficiently. The refrigerant inside stays too cold, ice forms on the coil surface, and airflow drops further. It's a self-reinforcing problem: less airflow → colder coil → more ice → even less airflow.

5. Refrigerant Metering Device Failure

The TXV (thermostatic expansion valve) or orifice tube controls how much refrigerant flows into the evaporator coil. If it sticks open or fails, too much refrigerant floods the coil at once. The coil temperature drops sharply, and ice forms fast.

This one requires proper pressure testing to diagnose. It's not something you can spot visually.

Before you call, there are a few safe checks you can do yourself. These won't fix the problem, but they'll help you understand what you're dealing with and they might prevent additional damage.

Step 1: Turn the system to "fan only" mode. Switch your thermostat from "cool" to "fan only." This keeps air moving over the coil without the refrigeration cycle running. It lets ice melt safely without flooding. Do not run the system in cooling mode with ice on the coil.

Step 2: Check your air filter. Pull the filter and look at it. If it's gray, clogged, or you can't see light through it, that's a restricted airflow problem. Replace it. If the system was running with a clogged filter, that alone may have caused the freeze-up.

Step 3: Check the drain pan. Look under the indoor unit. Is the pan full of standing water? Is water dripping onto the floor? If so, the drain line is likely clogged. Don't try to force-clear it with a shop vac unless you know what you're doing you can push debris further in.

Step 4: Let the ice melt completely before restarting. This can take 1–3 hours. Have towels ready. Once the ice is gone and you've replaced the filter, you can try restarting the system in cooling mode. If it freezes again within an hour or two, stop running it and call.

When to call immediately: - Ice is forming rapidly and won't stop - Water is actively damaging flooring, walls, or ceiling - You smell something burning near the air handler - The system won't turn on at all after the ice melts

📞 Call (208)916-1956 - 24/7 emergency service.