Frigidaire Freezer Running Constantly & Not Defrosting — 5 Causes & How to Fix

Your Frigidaire freezer sounds like it's training for a marathon — running nonstop, building up frost faster than a Minnesota winter, and your energy bill's climbing every month. One homeowner put it perfectly: "Freezer was running all the time and this part looks like it solved the problem." That part? The defrost thermostat, and when it fails, your compressor never gets the signal to take a break.

The defrost thermostat (part 297216600) is the gatekeeper for your freezer's defrost cycle. It monitors evaporator coil temperature and tells the defrost heater when to fire up. When it sticks closed or opens prematurely, you'll get a freezer that either frosts over like an igloo or runs continuously trying to compensate for warm temperatures.

Quick Symptom Check

Your freezer's trying to tell you something's wrong. Check these symptoms:

• Compressor never stops running — no clicking off, just constant humming
• Thick frost buildup on evaporator coils — more than a light dusting
• Freezer section feels warmer than usual — ice cream's softer, frost on packages melting
• Energy bill suddenly spiked — 24/7 operation adds up fast
• Fridge section too warm — because the whole system's struggling
• Ice buildup blocking air vents — restricting airflow between compartments

Cause #1: Failed Defrost Thermostat (Most Likely — 65% of Cases)

The defrost thermostat is a bimetallic switch clipped to the evaporator coils. It's supposed to close its contacts when coil temperature drops below about 15°F, allowing the defrost heater to warm things up. When it fails, it either stays open (no defrost cycles = ice mountain) or stays closed (constant defrost = warm freezer).

How to diagnose:

1. Unplug the fridge — seriously, don't skip this
2. Remove the freezer's back panel (usually 4-6 screws)
3. Locate the thermostat clipped to the evaporator coils — looks like a small plastic housing with two wires
4. Disconnect the wire harness and remove the thermostat
5. Set your multimeter to continuity/ohms
6. At room temperature, it should show NO continuity (open circuit)
7. Place it in your actual freezer for 10 minutes
8. Test again — it should now show continuity (closed circuit around 0-2 ohms)

If it shows continuity at room temp or won't close when cold, it's toast. One repair tech noted: "Removed trays and back panel. Replaced thermostat. Reinstalled back panel and trays. Freezer works fine again." That's the typical 15-minute fix.

Replacement cost: $26.99 for part 297216600, compatible with Frigidaire, Kenmore, Gibson, and Kelvinator models including GY2CRN2K and similar.

Cause #2: Defrost Heater Burned Out (20% of Cases)

Even if your thermostat's working, the defrost heater itself might've failed. It's a resistive heating element that melts frost off the evaporator coils during defrost cycles. When it burns out, frost accumulates until it blocks airflow completely.

Check for:

• Visible breaks or blistering on the heater element
• No continuity across heater terminals (should read 10-50 ohms depending on model)
• Scorch marks on surrounding insulation

If the heater's dead but your thermostat tested good, you've found your problem. Both parts often fail together after years of thermal cycling.

Cause #3: Defrost Timer Stuck in Cooling Mode (10% of Cases)

The defrost timer is the brain that schedules defrost cycles — typically every 8-10 hours of compressor run time. If it's stuck, your freezer never gets the memo to defrost, even with a working thermostat and heater.

Location varies by model:

• Behind the lower front grille
• In the control panel at the top
• Behind the refrigerator near the compressor

Try manually advancing the timer with a screwdriver in the slot on the dial. If the compressor shuts off and the defrost heater kicks on, the timer's likely faulty and needs replacement.

Cause #4: Defrost Control Board Malfunction (3% — Newer Models)

Modern Frigidaire models ditched mechanical timers for electronic adaptive defrost boards. These monitor compressor run time and door openings to optimize defrost cycles. When the board fails, defrost scheduling goes haywire.

Symptoms specific to board failure:

• Erratic defrost patterns
• Error codes on digital display
• Defrost cycles too frequent or never happening

Testing requires checking voltage output to the defrost heater during a defrost cycle. This one's trickier — if you're not comfortable with live voltage testing, call a tech.

Cause #5: Refrigerant Leak Causing Compressor Overwork (2% of Cases)

Rarely, a slow refrigerant leak makes the compressor run constantly trying to maintain temperature. The symptom looks identical to defrost issues — constant running, warm temps, frost buildup — but the root cause is different.

Red flags for refrigerant issues:

• Oily residue on copper lines
• Hissing sound near coils or compressor
• Compressor extremely hot to touch
• Both fridge AND freezer too warm despite constant running

Refrigerant work requires EPA certification and specialized equipment. Don't attempt this yourself.

The 15-Minute Defrost Thermostat Replacement

Since the defrost thermostat is the culprit 65% of the time and takes under 15 minutes to swap, start here. You'll need a Phillips screwdriver and nothing else.

Step-by-step:

1. Unplug the refrigerator completely
2. Empty your freezer contents (or at least move them aside)
3. Remove the screws holding the interior back panel — usually 4-6 screws around the perimeter
4. Carefully pull the panel forward — frost may have sealed it in place
5. Locate the defrost thermostat clipped to the evaporator coils on the left side
6. Disconnect the two-wire harness
7. Unclip or unscrew the old thermostat from its mounting bracket
8. Clip the new 297216600 thermostat in the same position — must make good contact with the coil
9. Reconnect the wire harness
10. Reinstall the back panel and screws
11. Plug in and monitor for 24 hours

As one DIYer confirmed: "Very easy to install." The thermostat just clips on — no special tools or HVAC knowledge required.

When to Call a Pro

DIY the thermostat replacement if you're comfortable with basic disassembly. It's genuinely easy and saves you $150+ in service call fees. But call a tech if:

• You replaced the thermostat and problem persists after 48 hours
• You see refrigerant oil or suspect a leak
• The defrost control board needs diagnosis (requires voltage testing with power on)
• You're not confident working around evaporator coils — they're fragile and expensive to replace if damaged
• Your fridge is still under warranty (DIY repairs can void coverage)

A professional diagnosis runs $100-$150. Defrost system repairs typically cost $200-$400 including parts and labor, depending on what needs replacement.

Preventing Future Defrost System Failures

Defrost thermostats fail from thermal stress — constant heating and cooling cycles over 8-12 years. You can't prevent aging, but you can minimize stress:

• Keep door seals clean — dirty seals let warm air in, forcing longer run times
• Don't overstuff the freezer — blocks airflow and makes defrost cycles work harder
• Check door alignment annually — sagging doors let in humid air that turns to frost
• Vacuum condenser coils twice yearly — dust buildup makes the whole system work harder

Frequently Asked Questions

How do I know if my defrost thermostat is bad without a multimeter?

Look for thick frost buildup on the evaporator coils combined with a freezer that runs constantly but doesn't stay cold enough. If manually advancing the defrost timer doesn't start a defrost cycle (heater doesn't warm up), the thermostat's likely failed open. A working thermostat should close its contacts when coils are cold, allowing the heater to operate. Without a meter, though, you're making an educated guess based on symptoms.

Can I just scrape off the frost instead of fixing the thermostat?

You can defrost manually as a temporary fix, but frost will return within days because the underlying problem remains. Manually defrosting every week is miserable and damages food quality. Plus, your compressor's still overworking 24/7, costing you $20-40/month extra on electricity. The $27 thermostat pays for itself in energy savings within two months and solves the problem permanently.

Will replacing the thermostat fix my warm refrigerator section too?

Usually yes, if the warm fridge is caused by the freezer problem. Most Frigidaire refrigerators cool the fridge section using cold air from the freezer. When frost blocks the air passage or the freezer can't maintain temperature, the fridge suffers too. After replacing the defrost thermostat and allowing 24 hours for temperature stabilization, both compartments should return to normal. If the fridge stays warm after 48 hours, you've got a separate issue like a failed damper control or evaporator fan.