Troubleshooting Common 20 kW Electric Furnace Issues: From Cold Air to

0 comments

👋 Introduction: Tony’s Golden Rule — “Don’t Panic, Diagnose”

Hey everyone — Tony here.

If your electric furnace suddenly starts blowing cold air, trips the breaker, or refuses to turn on, take a deep breath — it doesn’t always mean disaster.

I’ve been servicing Goodman furnaces for decades, and 90% of the issues I see with 20 kW models come down to simple fixes: airflow blockages, dirty filters, loose wires, or a tripped limit switch.

Goodman 68,240 BTU 20 kW Electric Furnace with 2,000 CFM Airflow - MBVK20DP1X00, HKTAD201

In this guide, I’ll walk you through how to diagnose and fix common furnace problems, when to call a professional, and how to prevent them from happening again.

⚙️ 1. How a 20 kW Electric Furnace Works (and Why It’s So Reliable)

Before you start troubleshooting, it helps to understand what’s going on inside your Goodman electric furnace.

A 20 kW furnace uses electric resistance coils to generate heat — no gas, no combustion, no flame sensor. It’s basically a giant, safe space heater with a high-powered blower that circulates warm air through your ductwork.

Main Components:

Heating Elements: 4–5 coils that generate up to 68,240 BTUs.
Sequencer: Turns the elements on/off in stages.
Blower Motor: Pushes 2,000 CFM of air through your ducts.
Limit Switches: Protects against overheating.
Thermostat & Control Board: Manage temperature and safety cycles.

Understanding these parts makes troubleshooting much easier — because once you know what each component does, you can pinpoint where the issue starts.

(Reference: Goodman MBVK Installation & Operation Manual )

❄️ 2. Problem: Furnace Blows Cold Air

This is one of the most common homeowner complaints — and usually the easiest to fix.

Possible Causes:

Thermostat set to “ON” instead of “AUTO.”
- The blower runs constantly, but the heating elements only energize on demand.
- ✅ Fix: Switch fan setting to AUTO.
Tripped limit switch or open high-temperature cutoff.
- Caused by restricted airflow or dirty filters.
- ✅ Fix: Replace filter, reset limit switch.
Failed heating element or sequencer.
- Elements wear out over time or develop breaks in the coil.
- ✅ Fix: Test with a multimeter for continuity; replace defective parts.
Loose wiring or burnt connectors.
- High amperage can loosen terminals or cause heat damage.
- ✅ Fix: Tighten and replace any discolored or melted connections.

(Reference: HVAC School – Electric Heat Diagnostics )

⚡ 3. Problem: Furnace Trips the Breaker

Breaker trips are scary — but they’re your system’s way of saying something’s drawing too much current.

Common Culprits:

Overloaded Circuit.
- The Goodman MBVK20DP1X00 needs two dedicated circuits — typically 60A and 100A.
- ✅ Fix: Verify breakers are correctly sized and wired.
Shorted Heating Element.
- A damaged coil can short to the metal frame, creating a direct path to ground.
- ✅ Fix: Turn off power, check elements for continuity and resistance.
Loose Wire or Corroded Connection.
- Increases resistance, generates heat, and pops the breaker.
- ✅ Fix: Inspect all lugs and tighten connections.
Blower Motor Overload.
- Dirt, seized bearings, or blocked airflow can make the motor draw excess current.
- ✅ Fix: Clean blower wheel and lubricate bearings.

(Reference: National Electrical Code (NEC))

🌬️ 4. Problem: Weak or No Airflow

If your furnace hums but barely blows air, the problem is airflow — not heat.

Check These First:

Dirty Filter:
- Most overlooked issue. A clogged filter can reduce CFM by 50%.
- ✅ Fix: Replace every 1–3 months (MERV 8–11 recommended).
Blower Motor Issues:
- Motor may not be spinning at full speed or capacitor could be weak.
- ✅ Fix: Check capacitor (should read within 10% of rating).
Duct Blockage or Leak:
- Collapsed flex duct or disconnected return line.
- ✅ Fix: Inspect ducts for kinks, gaps, and blockages.
Incorrect Blower Speed Setting:
- Some homeowners set the speed too low for quiet operation.
- ✅ Fix: Adjust blower tap to match your system’s CFM needs.

(Reference: Energy Vanguard – Airflow and Static Pressure )

🔥 5. Problem: Furnace Won’t Turn On

Nothing happens when you raise the thermostat? Start here.

Step-by-Step Diagnostic:

Check Power:
- Make sure both disconnects (60A + 100A) are ON.
Verify Thermostat Power:
- Ensure you have 24V between R and C terminals.
Inspect Fuses or Circuit Board:
- Blown 3A fuse on control board? Replace it.
Reset Limit Switch:
- Many Goodman furnaces have a manual-reset limit switch on the element housing.
Check Door Safety Switch:
- If the access panel isn’t seated properly, the switch cuts power.

If you’ve checked all these and still nothing — it’s time to call a pro. You might have a bad transformer or sequencer.

(Reference: Goodman Troubleshooting Guide – MBVK Models )

🌡️ 6. Problem: Furnace Overheats or Smells Hot

Overheating is serious — it means something’s restricting airflow or a safety limit is tripping repeatedly.

Common Causes:

Dirty filter or clogged ducts.
Loose wiring on heating elements.
Failed limit switch or sequencer sticking ON.

✅ Fixes:

Replace filter and inspect ducts.
Check temperature rise (should be 45–55°F).
Verify each heating stage cycles properly.

If you smell burning insulation, shut down the furnace immediately and call a technician.

(Reference: HVAC School – Limit Switch Testing )

🧊 7. Problem: Blower Runs Constantly

If your blower never shuts off, it’s either a thermostat setting or a control issue.

Quick Fixes:

Set fan mode to AUTO, not ON.
Test limit switch (if stuck closed, it’ll keep the blower running).
Check control board for shorted fan relay.

A constantly running blower doesn’t damage the system — but it wastes electricity and can cool the house too much.

(Reference: EnergyStar – Smart Thermostat Operation)

🧰 8. Tony’s Pro Troubleshooting Tips

Here are a few rules I live by when diagnosing electric furnaces:

Always start with power and airflow.
Nine times out of ten, those are the culprits.
Listen to the furnace.
Clicking = relay, humming = motor, silence = power issue.
Use a digital multimeter.
Check for 240V at main lugs, 24V at the board, and continuity on each heating element.
Feel for heat stages.
Each heating stage should add roughly 10 kW (~34,000 BTU) of heat.
Never bypass a limit switch.
They’re there for safety. If it’s tripping often, find out why.

🧾 9. Preventing Future Issues

Here’s how to keep your Goodman 20 kW furnace running like new:

Task	Frequency	Why It Matters
Replace air filter	Every 1–3 months	Prevents overheating
Tighten electrical connections	Yearly	Avoids breaker trips
Vacuum blower & coils	Yearly	Improves airflow
Test temperature rise	Yearly	Verifies efficiency
Schedule professional tune-up	Annually	Ensures safe, optimal operation

(Reference: ENERGY STAR – Furnace Maintenance Tips)

🧠 10. When to Call a Professional

You can handle most of the basics yourself — but call an HVAC tech if you notice:

Breakers tripping repeatedly.
Burning or electrical odors.
Heating elements glowing red-hot for too long.
Wires or connectors visibly melted.
Furnace cycling on and off every few minutes.

A professional can test amp draw, verify heat staging, and check sequencers with precision tools — ensuring safety and long-term performance.

🏁 Conclusion: Keep Calm, Keep It Clean, Keep It Running

The Goodman 20 kW electric furnace is built tough — and when properly maintained, it can deliver 20+ years of reliable comfort.

But even great equipment needs a little help now and then.

If your furnace is blowing cold air, tripping breakers, or acting up, start with the basics: filters, power, and airflow. You’ll be surprised how many “big” problems come down to small, easy fixes.