Installation Guide: What Mark Looks for When Setting Up a Goodman 2.5

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Installing a central AC system isn’t just about connecting a few wires and flipping a switch. In my 15+ years of working with Goodman systems, I’ve seen installs done right—and installs done wrong. The difference comes down to details at every step.

In this guide, I’ll walk you through what I personally look for when setting up a Goodman 2.5 Ton 13.8 SEER2 Northeast System (condenser model GLXS3BN3010 + air handler model AMST30BU1300). Whether you’re a homeowner trying to understand the process or a DIYer who wants to know what a pro checks, this is your roadmap.

📋 Step 1: Pre-Install Assessment

Before I even bring equipment inside, I run a full pre-install check.

🔍 Load Calculation (Manual J)

A 2.5-ton system = 30,000 BTUs/hour, but that doesn’t mean it’s right for every home.
I use Manual J software to account for insulation, window types, sun exposure, and occupancy.
If the load comes back closer to 24,000 BTUs, I may recommend a 2-ton instead. Oversizing is just as bad as undersizing.

👉 Homeowners: If your installer doesn’t mention Manual J, that’s a red flag.

Learn more about Manual J from ACCA

📐 Ductwork Evaluation

I measure existing ducts to ensure they can move 400 CFM per ton (about 1,000 CFM for a 2.5-ton system).
Undersized or leaky ducts kill efficiency.
I also check for insulation around ducts in unconditioned spaces (attics, basements).

ENERGY STAR’s guide on ducts

⚡ Electrical Panel Check

Goodman’s 2.5-ton condenser usually needs a 25–30 amp breaker.
I make sure the home’s electrical panel has capacity and meets NEC code.

🧹 Step 2: Site Prep & Clearance

Next up is prepping the install site.

🏡 Outdoor Condenser Placement

Needs to sit on a level pad (concrete or composite).
Minimum 12–18 inches clearance from walls, and 5 feet above the unit for airflow.
Away from dryer vents or roof drip lines.

🗄️ Indoor Air Handler Placement

Basements, attics, or utility closets work fine—but I always check for service clearance.
Goodman recommends at least 24 inches in front for servicing filters and coils.

💧 Drainage Setup

Condensate line must slope downward and exit safely.
In basements, I often add a condensate pump to lift water to a drain.

📦 Step 3: System Components Check

When the equipment arrives, I don’t assume it’s perfect.

📦 Inspection for Damage

I check fins on the condenser coil for dents.
Verify that blower motor and fan spin freely.

✅ Model Verification

Always confirm that the condenser (GLXS3BN3010) matches the air handler (AMST30BU1300).
Goodman’s systems are AHRI-rated when properly paired.

Check AHRI ratings database

🛤️ Line Set Planning

Goodman 2.5-ton units typically use a 3/4” suction line and 3/8” liquid line.
I measure the distance between indoor and outdoor units—longer than 25 feet may need charge adjustment.

❄️ Step 4: Refrigerant & Line Set Considerations

This is where I see a lot of mistakes from inexperienced installers.

🔧 Proper Sizing

If lines are too small, friction loss reduces efficiency.
If too large, oil return issues can damage the compressor.

💨 Leak Testing

I pressurize with dry nitrogen to at least 150 psi and check all brazed joints with soap bubbles.

⚠️ Refrigerant Handling

Goodman 13.8 SEER2 systems typically use R-410A, though R-32 variants are rolling out.
Charging must follow superheat/subcooling method—not guesswork.

EPA refrigerant safety guide