Troubleshooting Guide: What to Do If Your GE Wall Unit Isn’t Heating or Cooling Properly

Introduction: The Day My GE Unit Left Me Sweating (Or Shivering)

One mid-July afternoon, I strolled into my living room and hit the GE 12,000 BTU Through-the-Wall Air Conditioner with Electric Heat (AJEM12DWJ) to “Cool.” But instead of that satisfying blast of cold air, I got... well, warm air. My heart raced. Had I broken a $1,000 appliance already?

Before calling for help, I remembered some basic checks I’d once read in the GE Troubleshooting Tips for the AJEM12DWJ. A quick look, a filter rinse, and—voilà—my cool air was back. No service call needed.

That’s why I put together this detailed, user-friendly troubleshooting guide. We'll cover:

• First-step checks

• Common cooling and heating problems (and DIY fixes)

• Red flags for when it's time to call a pro

• Smart preventative care

Whether you’re already a GE AJEM12DWJ owner or just want prep for future hiccups, this guide is your go-to.

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Quick First Checks – Rule Out the Basics

Before diving in deep, always start with these simple but crucial checks:

1. Is the Unit Properly Powered?

Ensure it’s plugged into a 208/230 V outlet. A tripped breaker = no power. Flick your panel switch and double-check the unit’s power source.

2. Thermostat Mode Set Correctly?

Set to Cool when cooling, Heat when it’s colder. Also verify the temperature setpoint—too narrow a gap and the unit may not kick in at all.

3. Is the Air Filter Clean?

A clogged filter can choke airflow, cutting both cooling and heating power dramatically.

4. Are Doors and Windows Closed?

This sounds obvious, but drafts can undermine performance. Make sure your space is sealed properly.

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Common Cooling Issues & DIY Fixes

1️⃣ No Cold Air or Blows Warm Air

Possible Causes:

• Dirty filter or coils

• Thermostat mis-set

• Low/empty refrigerant (requires pro service)

Fixes:

• Clean the filter and vacuum coils gently

• Switch to “Cool” mode and lower the temperature

• If still not cooling properly, it may be a refrigerant leak—this needs an HVAC technician.

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2️⃣ Weak Airflow

Possible Causes:

• Blocked vents

• Clogged filter

• Unit shifted in wall sleeve

Fixes:

• Clear obstructions like furniture or drapes

• Wash the filter

• Re-seat the unit in its sleeve, ensuring a snug fit

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3️⃣ Short Cycling (Turns On/Off Rapidly)

Possible Causes:

• Oversized unit relative to room size

• Thermostat reading incorrect temps (e.g., placed near heat source)

Fixes:

• Move heat gadgets (lamps, TVs) away from thermostat sensor

• Use fan mode for air mixing—helps smooth temp swings

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4️⃣ Water Leaks or Condensation

Possible Causes:

• Blocked drain pan

• Improper sleeve tilt (should tilt slightly downwards)

Fixes:

• Clean the drain channel

• Adjust sleeve tilt outward (about ¼″ downward slope) to ensure water flows outside

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Heating Mode Problems & Troubleshooting

1️⃣ No Heat Output

Possible Causes:

• Mode not set to “Heat”

• Tripped breaker

• Faulty heating element (requires professional repair)

Fixes:

• Set to “Heat”

• Reset breaker

• Still no heat? Time to call a qualified technician

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2️⃣ Weak Heat Output

Possible Causes:

• Dirty filter

• Drafts around the sleeve allowing cold infiltration

Fixes:

• Clean filter as part of monthly maintenance

• Reseal gaps with caulk or weatherstripping for better efficiency

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3️⃣ Burning Smell at Startup

Possible Reasons:

• Dust burning off (especially if not used recently)—normal if short-lived

• Persistent burning odor may signal electrical issues

Fixes:

• Let the unit run for 10–15 minutes—the smell should dissipate

• If it doesn’t, shut off unit and contact a technician immediately

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Noises, Smells & Other Red Flags

Here’s how to decode a few warning signs:

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When to Skip DIY and Call the Pro

Call for help when:

• Cleaning/resetting doesn’t fix warm air output (possible refrigerant issue)

• Heating element is clearly failing to operate

• Breakers trip repeatedly when the unit runs

• There’s a burning smell that lingers or returns

Pro-safe troubleshooting like GE’s official troubleshooting tips or fault-code diagnostics (refer to manual) can guide repairs effectively. 

Troubleshooting for AJEM12DWJ

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Prevent Future Problems with Simple Care

1. Clean or Rinse Filter Regularly

Monthly in peak use, every 2–3 weeks during winter heating.

2. Seasonal Coil & Drain Maintenance

Spring/Fall: vacuum coils, flush drain. This improves efficiency and prevents surprises.

3. Seal Gaps Around Wall Sleeve

Annual check ensures no drafts, moisture, or pests sneak in.

4. Annual Tech Inspection

A yearly pro check can verify refrigerant levels, tight electrical components, and overall condition.

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Samantha’s Troubleshooting Checklist

Cooling Issues:

• Verify power and breaker

• Ensure “Cool” mode is selected

• Clean filter and inspect coils

• Inspect vents and airflow

• Examine drainage and sleeve alignment

• If unresolved → Call technician (possible refrigerant or electrical issue)

Heating Issues:

• Check power and breaker

• Set to “Heat” mode

• Clean filter

• Seal any drafts

• Still no heat → Call technician (element failure)

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Conclusion: Stay Calm, Troubleshoot Smart

When my GE unit stopped cooling abruptly, I panicked. But a few quick checks revealed the issue—and fixed it without expense or stress. Most problems are simple to diagnose and resolve.

If in doubt, refer to troubleshooting tips in the GE Owner’s Manual or reach out to GE support directly. 

For more on this model and related accessories, check the AJEM12DWJ support page on GE Appliances' website. 

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In the next topic we will know more about: Cost Breakdown: How Much Does a GE 12,000 BTU Wall Unit Really Cost in 2025?