3.5-Ton Central Air Conditioners: Which One to Buy

Need something different?

• 

  Keeping your indoor coil

  Goodman GLXS4BA4210 · Outdoor unit only

  The outdoor unit alone, $1,037.53 less. Its rating depends on the coil it is paired with (14.3 to 15.5 SEER2 with Goodman's own coils), so your installer has to confirm your coil matches.

  $2,450.47 on Amazon
• 

  Northern states only

  Goodman GLXS3BN4210 + CAPTA4230C3 · Outdoor unit + coil

  $279 less, rated 13.4 to 14 SEER2. Federal rules allow 13.4 SEER2 only in the North region; in the South the floor is 14.3.

  $3,209 on Amazon
• 

  With an air handler instead of a coil

  Goodman GLXS4BA4210 + AMST42CU1300 · Outdoor unit + air handler

  For a home with no furnace (an attic or closet air handler moves the air).

  $4,332 on Amazon

Is 3.5 tons the right size?

Replacing a unit? Match the old one. On most outdoor units the size is in the model number: 42 means 3.5 tons (Goodman's GLXS4BA4210 is a 3.5-ton). The common rule of thumb is one ton per 400 to 500 sq ft, about 1,400 to 1,750 sq ft for 3.5 tons. The U.S. Department of Energy warns that rule ignores your climate and insulation, and recommends a contractor's load calculation (Manual J). Other sizes: 2 ton · 2.5 ton · 3 ton · 4 ton.

What it costs

Amazon prices read today. Installed prices are U.S. typical for a replacement on existing ductwork, equipment, labor and permit together, from EnergySage, Modernize and other published 2026 data (compiled July 2026). Buying the unit yourself still leaves the installer's labor, refrigerant work and permit to pay.

Before you order one online

1. Book the installer first. Goodman gives no warranty on equipment bought online unless a licensed dealer installs it to code. Ask whether they will fit a unit you supply. Charging the refrigerant needs EPA Section 608 certification.
2. Check your region. A 13.4 SEER2 unit is allowed only in the North. In the Southeast and Southwest buy 14.3 SEER2 or higher at this size.
3. Match the coil. The rating is for an outdoor unit and coil together. Buy them as a system, or have the installer confirm your coil matches.
4. Match the size. Read the size in your old outdoor unit's model number, unless the house has changed a lot.

Every 3.5-ton central AC we matched on Amazon (5)

3.5-ton central AC on Amazon: what is in the box, certified SEER2 range, region and price

Unit	In the box	SEER2 (AHRI)	Where allowed	Price	Buy
Goodman GLXS3BN4210	Outdoor unit only	13.4–14.5	North only	$2,148.24	Buy
Goodman GLXS4BA4210	Outdoor unit only	14.3–15.5	Every region	$2,450.47	Buy
Goodman GLXS3BN4210 + CAPTA4230C3	Outdoor unit + coil	13.4–14	North only	$3,209	Buy
Goodman GLXS4BA4210 + CAPTA4230C3	Outdoor unit + coil	14.3–15.2	Every region	$3,488	Buy
Goodman GLXS4BA4210 + AMST42CU1300	Outdoor unit + air handler	14.5	Every region	$4,332	Buy

SEER2 is the certified AHRI range for that outdoor unit with Goodman's own coils (for a system, with the coil in the box). Prices read live on Amazon today.

Questions buyers ask

How many square feet does a 3.5 ton AC cool?

The common rule of thumb is one ton per 400 to 500 sq ft, so about 1,400 to 1,750 sq ft. The U.S. Department of Energy warns that rule ignores your climate and how well the house is built, and says a contractor's load calculation (Manual J) is the real answer. When you replace a unit, match the size of the old one.

How much does a 3.5 ton AC unit cost?

On Amazon, $2,148.24 to $4,332 for the 5 Goodman listings here (the outdoor unit alone, or with its coil). Installed by a contractor, a 3.5-ton central AC typically runs $5,500 to $10,500, equipment and labor together.

Can I buy a central AC online and keep the warranty?

Yes, if a licensed dealer installs it. Goodman says it gives no warranty on equipment a homeowner buys online unless the unit is installed by a dealer who follows all federal, state and local codes and licensing rules. Line up the installer before you order.

Can I install a central AC myself?

No. Connecting and charging the refrigerant lines is work for a licensed installer, and in the U.S. it needs EPA Section 608 certification. Goodman's warranty also depends on a licensed install.

Is a 13.4 SEER2 AC legal where I live?

Only in the North region. Since January 1, 2023 the federal floor for split central AC is 13.4 SEER2 in the North and 14.3 SEER2 at this size in the Southeast and Southwest (the Southwest also sets an EER2 floor). Goodman sells its GLXS3BN units as North-region only.

Outdoor unit only, or with the coil?

A system with its matched coil is what the rating on the listing assumes. An outdoor unit alone only makes sense if your installer confirms your existing coil matches it; the certified rating changes with the coil it is paired with.