How to Compare AC Quotes Line by Line

The fastest way to compare AC quotes is to stop reading them as totals. Build one table with the same rows for every contractor, then mark each row as included, excluded, allowance, or not stated.

If a contractor cannot name the indoor equipment, capacity basis, duct scope, refrigerant work, permit, warranty, and startup procedure, you do not yet have a complete proposal.

The AC quote comparison table

Check	Quote A	Quote B	What a complete answer looks like
Outdoor model			Full model number
Indoor model			Coil, furnace, or air-handler model
AHRI reference			Certified matched-system record
Capacity			Nominal tons plus design-load support
Load calculation			Room-by-room Manual J or equivalent documented method
Efficiency			SEER2 and EER2 for the exact match
Refrigerant			R-454B, R-32, R-410A, or other, explicitly named
Compressor			Single-stage, two-stage, or variable capacity
Duct scope			Repairs, sealing, return changes, balancing
Line set			Replace or reuse, size, flush/clean method, testing
Electrical			Breaker, disconnect, whip, service scope
Condensate			Drain, trap, pump, overflow protection
Permit			Included, who pulls it, inspection included
Controls			Thermostat, sensors, proprietary requirements
Warranty			Parts, compressor, labor, registration, exclusions
Commissioning			Airflow and refrigerant-charge verification, recorded readings

1. Match the model numbers

An outdoor model by itself is not enough. Central AC ratings apply to combinations of outdoor equipment, an indoor coil or air handler, and sometimes a furnace blower. Use the AHRI Directory to verify the exact combination where a certificate is available.

Ask: "What are both model numbers, and what AHRI reference matches this combination?"

2. Ask what supports the tonnage

"Your old unit was 3 tons" is not a load calculation. Neither is "500 square feet per ton." ACCA Manual J accounts for climate, orientation, windows, insulation, leakage, occupants, and room-by-room loads.

A contractor may charge for a detailed design or provide it after a signed design agreement. That can be reasonable. What is not reasonable is treating the capacity as proven when no calculation exists.

Ask: "What design conditions and room-by-room load support this capacity?"

3. Make the duct scope explicit

New equipment does not fix undersized returns, crushed flex duct, leakage, missing insulation, or poor balancing. ENERGY STAR identifies airflow as a core installation issue because it affects capacity, efficiency, and comfort.

Ask whether the contractor will measure static pressure, verify airflow, seal accessible leakage, and correct any return-air restriction. If the quote says "duct modifications as needed," ask for a defined allowance or a price schedule.

4. Separate the refrigerant work

The proposal should state the refrigerant and what happens to the existing copper line set. New lower-GWP refrigerants have equipment-specific installation requirements. The contractor should follow the manufacturer's instructions, not improvise a generic reuse rule.

Ask how the line set is sized, pressure-tested, evacuated, and charged. You do not need to perform those steps. You need to know they are part of the job.

5. Read the warranty in three layers

Parts warranty: manufacturer terms, registration deadline, transfer rules, and exclusions.
Compressor warranty: sometimes longer than general parts coverage.
Labor warranty: the contractor's responsibility when a covered part still requires diagnosis, refrigerant, and installation labor.

"Ten-year warranty" is incomplete if it means parts only and requires registration the proposal never mentions.

6. Require a startup record

Quality installation is measurable. Ask what the contractor records at startup: airflow or static pressure, temperature split, electrical readings, refrigerant charge method, drain operation, thermostat setup, and system operation in each stage.

The point is not to turn the homeowner into a technician. It is to make completion testable.

Red flags that justify one more question

Only one equipment model number appears.
Tonnage is copied from the old nameplate without a load calculation.
"Up to" efficiency is quoted without the exact match.
Ductwork is excluded without an airflow check.
Permit is absent or described as optional.
The refrigerant or line-set plan is missing.
The labor warranty is verbal.
The quote expires today.

One red flag is not proof of a bad contractor. A refusal to clarify it is more informative.

Run the finalist through our 12 AC buying mistakes, warranty comparison, and new-installation checklist before signing.

Frequently Asked Questions

Should I choose the lowest AC quote?

Choose the lowest quote only after the scope is comparable. A lower total can be excellent when it includes the same matched equipment, design, duct work, permit, warranty, and startup checks. It is not cheaper if those items reappear later as change orders or comfort problems.

Do I need three AC quotes?

Two detailed, comparable proposals can be more useful than five vague ones. A third quote helps when the first two disagree on capacity, duct scope, or system type. The goal is not quote volume. It is a clear design and a fair scope.

What is an AHRI certificate?

AHRI certifies the published performance of specific equipment combinations. The directory record helps confirm that the outdoor and indoor units are a recognized match and identifies the rated efficiency for that combination.

Can an AC quote be too detailed?

Technical boilerplate can be long without being useful. The detail that matters is decision detail: exact equipment, capacity basis, included work, exclusions, completion tests, warranty, and total price.