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Troubleshooting Guide: What to Do If Your 3 Ton R-32 AC Isn’t Cooling (or Heating) Right

Tony Marino’s Step-by-Step Fixes Before You Call the Pros

🧠 Tony’s Intro: “Don’t Panic — Diagnose”

Every summer, I get the same call.

“Tony, my AC’s running, but it’s not doing anything.”

Nine times out of ten, it’s something small — a dirty filter, a tripped breaker, or a drain switch.
The truth is, most “failures” aren’t failures. They’re symptoms.

So before you shell out $300 for a service call, here’s my field-tested troubleshooting checklist for your 3 Ton Goodman R-32 system — written the same way I train new techs in the field.

We’ll walk through electrical, airflow, refrigerant, thermostat, and drainage issues — everything that keeps your system from cooling or heating right.

⚙️ 1. Know Your System Basics

If you own a Goodman GLXS4BA3610 condenser with the AMST36CU1300 air handler, it runs on R-32 refrigerant, rated around 14.5 SEER2.

That means you’ve got a high-efficiency, single-stage unit designed for about 36,000 BTU of cooling — enough for 1,400–1,800 sq ft of space.

Understanding that helps you diagnose like a pro:

Compressor runs at full capacity (not variable).
The blower uses an ECM motor that adjusts speed automatically.
Cooling relies on R-32’s smooth thermodynamic flow — leaks or clogs hit performance fast.

(Goodman MFG R-32 Specifications )

👉 Tony’s Take:
If your system’s not cooling, think air, refrigerant, or power. It’s always one (or a combo) of those three.

🔌 2. Step One — Check Power Supply

No power, no cooling. Simple.

a. Check the Thermostat

Make sure it’s set to Cool and the temperature is below room temperature.
Replace batteries (if it uses any).
If the screen is blank, pull the cover and check for 24 V from the control board.

b. Check the Breaker Panel

Find the AC and Air Handler breakers (two separate circuits).
Flip each fully off, then back on.

c. Check the Outdoor Disconnect

Pull the disconnect fuse block. If burnt or melted, replace with an identical rating (typically 30–40 A).

👉 Tony’s Tip:
If you reset the breaker and it trips again immediately — that’s not a fixable DIY issue. That’s a short or failing capacitor.

(NFPA Electrical Safety Code )

💨 3. Step Two — Airflow: The Silent Killer

About 70 % of “not cooling” complaints come down to airflow.

a. Check the Filter

Pull it out. If it looks like felt instead of mesh, replace it.
A clogged filter drops airflow, freezes the coil, and makes you think the system’s “low on freon.”

(Energy Star Filter Guide )

b. Check Supply & Return Vents

All vents should be open and unblocked.
Don’t close unused rooms — it increases static pressure and cuts cooling power.

c. Check for Ice on the Coil

If you see frost or ice:

Turn the system OFF.
Set thermostat to Fan Only.
Let it thaw for 2–3 hours.
Then check the filter again.

👉 Tony’s Field Rule:
“Airflow problems look like refrigerant problems until you actually measure pressure.”

🧊 4. Step Three — Check Temperature Split

Run the AC for 10 minutes, then measure the air temperature:

Location	Normal Range	What It Means
Return grille	75 °F – 80 °F	—
Supply vent	55 °F – 60 °F	—
Difference (ΔT)	16 – 22 °F	Normal operation

If ΔT is under 14 °F → airflow or refrigerant issue.
If ΔT is over 25 °F, → restricted airflow (dirty coil, blower, or filter).

👉 Tony’s Trick:
You can use a $20 infrared thermometer — no gauges needed.

🧯 5. Step Four — Drainage and Float Switch

Your air handler’s condensate pan has a float safety switch. When the drain clogs, it cuts power to save you from water damage.

(Energy Star Condensate Maintenance )

How to Reset:

Locate the PVC drain pipe near the air handler.
Pull the cleanout cap and pour 1 cup of vinegar or bleach mix.
Wait 30 minutes, then reset the thermostat.

👉 Tony’s Tip:
If it happens again soon, install a secondary drain or condensate pump — you’ve got a slope issue.

⚡ 6. Step Five — Capacitors and Contactors

If your outdoor fan hums but doesn’t spin, or the compressor won’t start:
It’s likely a failed capacitor or pitted contactor.

Symptom	Suspect	Quick Check
Humming, fan not spinning	Run capacitor	Push fan blade (if it starts, cap’s bad)
Clicking, no startup	Contactor	Check for 24 V coil voltage

👉 Tony’s Warning:
These store power — discharge with a resistor, not a screwdriver. If you don’t know how, stop and call a pro.

🧰 7. Step Six — Refrigerant Issues (When It’s Time for Gauges)

R-32 is a single-component refrigerant, so charge accuracy is crucial.
Too much = high head pressure; too little = coil freeze.

Signs you might be low on charge:

Bubbling or hissing at the evaporator.
Frost line halfway up the suction pipe.
Low ΔT (< 14 °F).

👉 Tony’s Rule:
Only an EPA-certified tech can legally measure or recharge R-32.
If you suspect a leak, turn it off and call service — running low risks of compressor damage.

🔥 8. Step Seven — If It’s Not Heating (for Heat Pump Systems)

Some 3 Ton R-32 setups include a heat pump or electric heat kit.
If you’re getting cold air in heating mode:

a. Check Mode

Set thermostat to Heat, fan to Auto.

b. Check Outdoor Unit

If the fan isn’t spinning or frost covers the coil → defrost failure.

c. Check Auxiliary Heat

If strips don’t engage, the breaker or sequencer could be bad.

(Energy.gov Heat Pump Operation Guide )

👉 Tony’s Take:
If you hear it click but no heat output, odds are your defrost board or outdoor sensor is the culprit.

🌬️ 9. Step Eight — Blower Problems

If the outdoor unit runs but no indoor air blows:

Problem	Likely Cause	Fix
Blower silent	Tripped breaker	Reset, test voltage
Blower hums only	Bad motor capacitor	Replace
Blower cycles erratically	ECM motor or control board	Tech diagnosis

👉 Tony’s Field Note:
ECM motors are sensitive — voltage drops or dirty filters kill them faster than anything. Use a surge protector.

💡 10. Step Nine — Thermostat Communication

Smart thermostats sometimes lose connection or “forget” settings.

Reboot the device.
Re-link to Wi-Fi.
Verify R and C wires are tight.

If the thermostat clicks but the outdoor unit doesn’t start, check 24 V at the Y terminal — no voltage = blown low-voltage fuse on the control board.

(Energy Star Smart Thermostat Troubleshooting )

👉 Tony’s Tip:
Always use the right transformer size (40 VA minimum for Wi-Fi thermostats).

🧊 11. Step Ten — Icing and Defrost Cycles

R-32 systems run slightly cooler discharge temps. In humid climates, coils may frost overnight.

If it happens:

Set the fan to On for 30 minutes to thaw.
Check that the defrost sensor (if a heat pump) is attached to the coil.

👉 Tony’s Advice:
If it freezes often, airflow is too low, or the charge is off. Don’t just keep thawing — fix the cause.

💧 12. Step Eleven — Duct Leaks

If one room’s hot and another’s freezing, it’s likely duct leaks or disconnected runs.

Check attic or crawlspace:

Look for collapsed flex ducts.
Seal with mastic (not tape).
Replace uninsulated runs.

👉 Tony’s Take:
A single 2-inch gap can lose 20 % of airflow. That’s the silent money leak no one sees.

🔋 13. Step Twelve — Static Pressure

Too much static pressure = blower strain + poor cooling.

Your tech should measure it (under 0.7 in WC ideal).

If you hear “whooshing” or “howling” vents, the static’s too high.

👉 Tony’s Tip:
Add a return vent or wider filter grille to breathe easier — it’s the cheapest airflow upgrade.

🧱 14. Step Thirteen — Noise Diagnosis

Every sound means something:

Noise	Likely Issue	Severity
Hiss	Refrigerant leak	⚠
Buzz	Contactor coil	⚙
Rattle	Loose panel	🧰
Squeal	Blower bearing	🚨
Pop	Duct expansion	Normal

👉 Tony’s Note:
If noise changes overnight, don’t ignore it — early fixes prevent compressor damage later.

🧾 15. Step Fourteen — Control Board & Fuses

Your air handler control board has a small 3–5 A blade fuse.
If your thermostat screen is blank and the outdoor unit won’t engage, check that first.

👉 Tony’s Trick:
Use a spare automotive fuse — same rating, same size.

🧰 16. Step Fifteen — When to Call a Pro

Call for service if:
✅ Breaker trips repeatedly
✅ Coil keeps freezing
✅ Refrigerant hiss continues after shutdown
✅ Compressor won’t start, but the fan does
✅ Drain pan overflows

👉 Tony’s Guideline:
If you’ve done steps 1–10 and it’s still misbehaving — that’s a refrigerant, control, or mechanical issue. Time for gauges, meters, and experience.

💬 17. Tony’s Quick-Fix Story

One of my Florida clients thought her compressor died mid-July.
Turns out a frog had wedged itself into the contactor.
Two minutes, one small critter relocation, and the “broken” system was as good as new.

👉 Moral:
Not every no-cool is catastrophic. Always check the obvious before the expensive.

💡 18. Preventive Moves After You Fix It

Task	Frequency	Benefit
Filter change	1–2 months	Airflow stability
Coil rinse	2× year	Lower head pressure
Drain flush	3 months	Prevent float trips
Annual tune-up	1× year	Keeps warranty valid

👉 Tony’s Rule:
Every $1 spent on maintenance saves $4 in repair.

🌎 19. R-32-Specific Tips

R-32 is mildly flammable (A2L), but safe when installed correctly.
If you smell a faint “sweet chemical” odor or hear a hiss:

Shut off the power.
Ventilate.
Call a licensed R-32 technician.

👉 Tony’s Note:
Never use leak sealant chemicals — they gum up expansion valves.

🏁 20. Tony’s Final Word

Your 3 Ton R-32 air conditioner is a precision machine — and 80 % of problems can be fixed with basic maintenance and a few minutes of attention.

Whether it’s a tripped float switch or a bad capacitor, you can save serious time and money by learning to diagnose the basics before calling in backup.

👉 Tony’s Bottom Line: