Introduction
If you're installing a new Goodman GLXS4BA3610 condenser with an AMST36CU1300 air handler, you’ve already made a solid choice for energy-efficient, R-32-based cooling. But even the best systems can’t perform properly if the install goes sideways. I’ve been on too many jobs where folks thought everything was fine—until summer hit and the system struggled to cool, tripped breakers, or worse, failed completely.
Let’s walk through the most common installation mistakes I’ve seen with this system—and how to avoid them before they cost you.
1. Improper Line Set Sizing or Length
The R-32 refrigerant in your GLXS4BA3610 system runs best within a specific line set size and length range. Deviating too far outside those specs causes performance loss and high head pressure issues.
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Common mistake: Using an existing R-410A line set without checking compatibility or size.
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What to do instead: Refer to Goodman's official line set sizing guide and always verify the max allowable vertical separation and total equivalent length for R-32.
👉 Pro tip: Always pressure-test and triple-evacuate the lines before charging.
2. Skipping DIP Switch Configuration
The AMST36CU1300 air handler uses DIP switches to set airflow, fan delays, and electric heat options. Skipping this step is a recipe for low airflow, poor dehumidification, or coil freezing.
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Common mistake: Leaving factory DIP switch settings as-is.
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How to avoid it: Use the installation manual airflow table to match the CFM to your home’s duct design and static pressure. If you're unsure, AAON’s guide to static pressure tools is a must-read.
👉 Don’t just match size—match static pressure, heating mode airflow, and blower speed for the whole system.
3. Poor Drainage Setup on the Air Handler
The AMST36CU1300 includes a primary and optional secondary drain. If you skip a proper trap or fail to install the overflow switch, you’re risking leaks and ceiling damage—especially in attic installations.
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Common mistake: Forgetting the P-trap or assuming gravity drainage will work.
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Best practice: Follow Goodman’s spec for drain trap dimensions and always install a float switch in the secondary pan. The HVAC School podcast on condensate drainage explains exactly why this matters.
👉 Level the unit, test the drain with water before closing the panel, and insulate the drain line in humid climates.
4. Undersized or Poorly Sealed Ductwork
Even the most efficient 3-ton unit can’t push air through kinked, undersized, or leaky ductwork. This is a common mistake in system replacements, where the old ducts just don’t match the new system’s airflow requirements.
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Common mistake: Reusing existing ductwork without verifying static pressure or insulation.
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How to avoid it: Get a duct evaluation before install. Use Energy Vanguard’s duct sizing rules to ensure your returns and supply trunks match the system’s airflow spec.
👉 A blower door test can expose hidden leaks and bottlenecks that ruin comfort and efficiency.
5. Guessing the R-32 Charge Without a Scale
The GLXS4BA3610 is pre-charged, but anything beyond 15 feet of line set usually needs an adjustment. Overcharging or undercharging R-32 affects both performance and compressor longevity.
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Common mistake: "Eyeballing" the charge or relying on pressure only.
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Better method: Weigh in your charge with a digital scale and use MeasureQuick or similar apps to verify superheat/subcooling under operating load.
👉 Keep your recovery tank R-32 labeled and purge nitrogen before final vacuuming to avoid contamination.
Final Thoughts
Installing the Goodman GLXS4BA3610 + AMST36CU1300 system right the first time ensures you get the performance and efficiency you paid for. From DIP switches to drainage, every detail counts.
For those looking to avoid costly callbacks or DIY regrets, The Furnace Outlet has the full system package here—plus tech support if you need it. It’s always worth checking your steps against the manual, a pro installer, or someone who’s done it more than once.
Having condensation issues? Visit: Fixing Drainage and Overflow Issues on the AMST36CU1300 Air Handler.
Until next time,
- Mark, your go-to HVAC tech
