1. Quick answer
Separate no display or fan from fan running but no cooling. Check remote batteries, timer, mode and a dry accessible power source before calling service. A compressor may have a brief restart delay. If the breaker trips again, the cord is damaged or water is near power, stop; no live tests or cabinet opening.
A heat-sensitive person should move to another cool location while the equipment is out. Repeated pressing of the power button or rapid plug cycling rarely repairs a fault. Record what the unit actually does so a technician can distinguish controls from power and cooling problems.
2. Before you start
| Item | Plan |
|---|---|
| Tools | Exact owner's manual, flashlight, fresh remote batteries, phone to photograph the display |
| Time | 15–30 minutes of safe checks |
| Difficulty | Easy user controls; mains and internal electrical work is pro only |
| Safety | No wet outlets, live probing, capacitor testing or repeated breaker resets. Never touch electrical equipment or a breaker while standing in water. |
Key takeaway: Tools: plan — Exact owner's manual, flashlight, fresh remote batteries, phone to photograph the display.
Observe without touching first: is the display dark, is a fan audible, does a remote icon appear, is a timer set, and did a protection device trip? Photograph any code before attempting the manufacturer's documented restart.
3. Causes ranked by likelihood
| Cause | How to check | Safe fix | Difficulty |
|---|---|---|---|
| Remote batteries, lock or timer | Try supported controls; inspect display settings | Fresh batteries; clear timer or lock per manual | Easy |
| Mode, set point or compressor delay | Compare room temperature and mode | Select Cool; wait stated delay | Easy |
| Dry, accessible power connection | Inspect plug/outlet visually from dry area | Correct a loose safe plug only if undamaged | Easy |
| Plug/circuit protection or supply problem | Read exact manual and breaker state from a safe dry place | One manual-approved reset only if safe; service if recurring | Moderate |
| Portable full tray or protection code | Record code; consult exact model instructions | Approved emptying only | Easy–Moderate |
| Electrical control, motor or compressor fault | No response after safe checks; odor/trip | Qualified diagnosis | Pro only |
Key takeaway: Remote batteries, lock or timer: how to check — Try supported controls; inspect display settings.
Never infer that “no cooling” means “no power.” The fan may be operating normally while the compressor waits or has failed. The right first question is what visibly operates.
4. Detailed numbered fixes
1. Verify the controls and remote
Stand where you can see the unit display, then press its normal power control as described in its manual. A remote can lose battery contact while the indoor head still has power. Replace remote batteries in the specified orientation, check for a child lock or sleep timer, and aim the remote at the correct sensor. Do not pry apart the AC control housing if the remote still cannot command it.
On a split, the indoor head may have model-specific indicators and a manual operation feature, but not all do. Use only a clearly documented user control; avoid switches hidden behind fixed covers. Note whether the display changes with a button press. This observation gives service a better clue than “dead.”
If a timer schedules start for later, cancel it according to the manual and try one normal start. If no lights appear at all, proceed to safe power observation; if lights appear but cooling does not, the issue may be mode or compressor timing instead.
2. Set Cool and respect the restart delay
Select Cool mode and choose a temperature reasonably below the room reading. Fan mode alone cannot remove heat. On a heat-pump mini-split, Auto or Heat modes may behave differently than expected. Check whether a Wi-Fi schedule, sleep program or demand-saving mode is active, and change only one setting at a time.
After a power interruption or quick shutdown, compressor protection may delay cooling for several minutes. The fan can start first. Use the exact model's stated wait, not a universal fixed count. Constant unplugging restarts that waiting period and can hide an intermittent fault.
If the fan runs but the room stays warm beyond a reasonable period, use AC not cooling. Do not diagnose a compressor by touching a metal line or opening a cabinet.
3. Inspect a dry, safely accessible power source
Look for a loose plug, cracked housing, discoloration, heat damage or a pinched cord without touching a suspect connection. If the cord and receptacle are intact, dry and easily reachable, check that the plug is fully seated as the manufacturer directs. A room AC may require a dedicated circuit or specific voltage; confirm its label and manual, not an extension cord or adapter.
Do not use a power strip, defeated ground pin or improvised adapter to get a window unit running. Large cooling loads can overheat an inadequate connection. A portable with a built-in protective plug must be used as its manual directs; do not bypass or replace the protection with an ordinary plug.
If there is standing water or an outlet is wet, do not touch the plug or breaker while standing in water. Leave the area and obtain qualified help. A dry outlet that appears dead may still represent a wiring problem; never stick probes or tools into it to “check.”
4. Treat breaker and plug protection carefully
From a safe, dry location, you may observe whether a breaker has tripped. Some manuals describe a single safe reset after a known temporary event. If the breaker or protective plug trips again, stop. An oversized breaker, repeated resets or a different outlet is not an appropriate workaround for a faulty machine or circuit.
If several household outlets are affected, an electrician should evaluate the supply. If only the AC triggers protection, a qualified technician may need to examine the unit and its circuit. Internal components, including capacitors, may hold hazardous charge even after disconnection. No consumer should open the enclosure or test them.
Remember that a cord can look intact while its internal protection or a supply issue prevents operation. Do not cut off a plug for replacement or attempt a live circuit test. Provide the exact model and the observed trip pattern to service.
5. Check model-specific water and protection messages
A portable unit may refuse to cool when collected condensate fills its tray. Midea's US portable FAQ lists P1 as a full bottom tray on covered models. Frigidaire also documents P1 for certain room units. Follow your model's exact approved emptying procedure; ports and operating modes differ.
Never tip the cabinet, drill a drain or pull an unknown cap. Keep water out of power connections. An error may also indicate sensor or communication trouble requiring service. LG's room and split support explains different display styles. Photograph the code before any manual-approved reset.
If the same protection returns immediately after the approved step, stop and ask the manufacturer or a technician. An error clearing after one reset does not prove the underlying issue has been repaired.
6. Escalate internal or repeated failures
If the unit remains completely dark despite safe control and dry source checks, ask a qualified electrician or HVAC technician to distinguish the supply from an equipment fault. If it starts but shuts down immediately, note how many minutes it runs, whether a code appears and whether protection trips. This helps service without exposing you to a live electrical test.
Do not touch contactors, test capacitors, remove a compressor cover, connect refrigerant gauges or follow an online pressure target. A licensed HVAC technician with appropriate EPA Section 608 certification handles any refrigerant work. A failed compressor is not proven by a click alone.
For a window AC, note whether the trouble began after moving the unit or after a storm. Do not lean outside to inspect a wire or reach for a plug behind an unstable cabinet. For a portable AC, note whether an exhaust or drain change preceded the shutdown. A unit reporting a full tray may intentionally suspend cooling while its control display remains lit; that is not the same as a dead power supply.
For a mini-split, the outdoor condenser and indoor head may be powered and controlled as a system. An unresponsive head does not establish that the remote is defective, nor does a moving outdoor fan establish that the indoor controls are safe to open. Contact the installer with both unit model numbers if available, any code, and whether other equipment on the circuit still works. Building-wide outages or utility interruptions should be addressed through the appropriate provider rather than a cabinet repair.
When normal power returns after an outage, use the manual's restart instructions and allow the protective delay. If a repeated trip occurs on the first start attempt, leave the unit off. Never plug a room AC into a different circuit merely to defeat the protection that has been tripping; a circuit may have different requirements and the original problem still exists.
5. Brand-specific notes
Some LG room models show CH02 or E1; LG's room-code article does not mean a split head with a similar display has the same issue. Frigidaire identifies AS as a room-temperature thermistor fault on covered room units. GE support discusses model-specific error and function codes; Midea portable P1 concerns the tray on covered models.
Codes vary by model, so confirm in your owner's manual or the manufacturer's support site. A sensor fault or other internal code is service information, not permission to replace a component behind a live control panel.
6. When to call a professional
Call for repeated breaker/protective-plug trips, burnt odor, damaged wiring, wet receptacles, a hardwired mini-split with no response, or persistent failure after safe settings checks. A qualified electrician can examine the circuit; a licensed HVAC technician can evaluate the equipment. Refrigerant service requires appropriate EPA Section 608 certification.
Ask for a written diagnosis and warranty check before authorizing expensive work. Published costs are approximate US national planning ranges, not surveyed precise averages; region, equipment type, electrical scope and model determine the real quote. For an older inexpensive room unit, major internal repair may be less practical than replacement.
7. Prevention tips
- Keep the model manual and a photo of the rating label for future power and code questions.
- Avoid extension cords, power strips and overloaded circuits.
- Keep window seals and condensate paths consistent with the exact installation instructions.
- Inspect dry visible cords for damage before cooling season.
- Clean the user-removable filter so the unit does not operate under avoidable restriction.
- Protect the remote from dead batteries and accidental schedules.
- Investigate the first repeated trip instead of repeatedly resetting protection.
8. More help
Back to the Air Conditioner Guide. For a working fan with warm output, see AC not cooling. If a start attempt makes a new buzz or rattle, see AC making noise. Read electronics safety basics for power-related stop signs.