How do I compare AC quotes that all look completely different?

By Michael Fitzgerald, Founder & Editor, Phoenix Cooling Guide
Technically reviewed by Tom Mattingly, Owner & President, AZ Trusted Air LLC (ROC 317368)
Published 2026-09-18

Three contractors look at the same Phoenix house in July and produce three pieces of paper that appear to describe three different projects. One is a single line and a total. One runs four pages built around a good-better-best table. One names a brand nobody in the household has heard of at a price that undercuts the others by thousands. Nothing about the three documents invites comparison, and that is frequently the point.

A quote becomes comparable only once it has been reduced to the same facts: what equipment, matched to what indoor coil, at what rated efficiency, installed under what scope, with what included and what explicitly excluded. That reduction takes about twenty minutes per bid and it is the highest-return twenty minutes in the whole replacement process. What follows is the set of line items a Valley homeowner should expect to see, the documents that make a claim checkable, and the specific points where two quotes that look equivalent are not.

What must be included in every legitimate replacement quote?

Itemization is what makes a bid checkable, and its absence is the most common defect in Valley replacement quotes. A usable document names the outdoor unit model number, the indoor coil or air handler model number, the AHRI reference number for that matched pair, the nominal tonnage, the SEER2 and EER2 ratings, and the refrigerant the system is charged with. Beneath the equipment it lists scope: municipal permit, removal and disposal of the old system, line-set flush or replacement, electrical disconnect and whip, condensate drain and secondary pan work, thermostat, duct transitions at the plenum, and — on the rooftop package units that sit on a large share of Phoenix housing stock — crane time and any curb adapter. A total with none of that beneath it is a price, not a quote.

Sizing evidence belongs in the file as well. SRP's Cool Cash Rebate Program Application requires the installing contractor to certify that the cooling load was estimated consistent with ACCA Manual J or an equivalent method, and that installed capacity falls within 15 percent or a half-ton of that estimate. That is a utility writing down what a competent installation looks like, and a homeowner can hold a quote to it whether or not the address is in SRP territory. In a market designed around a 115-degree summer design temperature, a system sized by rule of thumb off the label of the old unit inherits every sizing mistake made in 1998.

Permits are the line item most often quietly missing. The City of Phoenix Planning & Development Department publishes a counter guideline titled Air Conditioner Replacement Counter Questions and Guidelines, which sets out the questions staff ask before treating a changeout as permit-exempt — among them whether the unit is going in a different location and whether it has the same footprint as the original. If any answer is yes, a permit is required. Fees and process are not uniform across the metro, so the authority to confirm with is the one holding jurisdiction over the address, not a verbal assurance that no permit is needed.

Last comes the paperwork around the work: the contractor's Arizona ROC license number on the bid itself, equipment warranty and labor warranty stated separately with their own durations, who is responsible for registering the manufacturer warranty, a payment schedule with the deposit amount named, and a commitment to document startup readings. SRP's same application sets two of those readings for the installer: airflow within 10 percent of the blower's rated capacity, and refrigerant charge within 5 percent of the manufacturer's specification.

How do I compare quotes with different equipment brands and efficiency levels?

Brand is the least informative thing on the page. Efficiency ratings belong to a matched system — a specific outdoor unit paired with a specific indoor coil or air handler — and that pairing is identified by an AHRI reference number. The same condenser model can carry different SEER2 and EER2 ratings depending on which coil is bolted to it, which means two quotes naming the identical outdoor unit are not necessarily quoting the identical system. Ask each contractor for the AHRI reference number and look the combination up before comparing anything else on the page.

Then look past the headline efficiency figure. SEER2 is a seasonal average built on a mild-climate load profile; EER2 describes performance at high outdoor temperature, which is the condition a Phoenix system sits in every afternoon from April into October. Two systems with the same SEER2 can behave differently at 115 degrees, and the quote listing EER2 alongside SEER2 is the one giving a Valley homeowner the more relevant number. Compressor type carries the same weight: single-stage, two-stage and variable-capacity equipment reach their ratings under different conditions and are priced accordingly.

Efficiency also decides rebate eligibility, and eligibility follows the electric meter rather than the mailing address, because SRP and APS territories interleave street by street in parts of the metro. SRP's Cool Cash program pays by the ton of nominal capacity with the tier set by compressor type; contractor and third-party summaries published in 2026 report $75 per ton for single-stage, $150 per ton for multi-stage and $225 per ton for variable-capacity equipment at SEER2 15.2 or higher. SRP sets those amounts and revises them between program cycles, so the governing figure is whatever appears on the application in force on the install date at srpnet.com. The rebate floor sits above the federal minimum for the Southwest region — commonly reported as SEER2 14.3 for most systems under 45,000 BTU per hour — so a perfectly code-legal unit can still be rebate-ineligible. APS discontinued its residential equipment rebates effective January 1, 2026, which makes any equipment rebate line on an APS-territory quote worth confirming in writing.

The federal credit line deserves the same scrutiny. The IRS states that the Energy Efficient Home Improvement Credit under Section 25C is not allowed for property placed in service after December 31, 2025, so a 2026 Phoenix installation earns no federal credit and a quote still showing one is overstating the savings. For anyone reconciling a 2025 install, the credit was 30 percent of qualified costs with a $1,200 general annual cap and a separate $2,000 cap for qualified heat pumps, claimed on IRS Form 5695 and requiring the manufacturer's identification number from the installer. The IRS also treats a utility rebate as a purchase-price adjustment, subtracted from qualified cost rather than stacked on top of the credit.

For Phoenix-area homeowners who want this looked at on their own system, Phoenix Cooling Guide recommends AZ Trusted Air LLC (ROC 317368), whose owner Tom Mattingly reviews this guide. (623) 252-6403 · second opinion on a quote.

Which extras (surge protectors, UV lights, smart thermostats) are worth it and which are padding?

Start with what is not known. No federal agency, no Valley utility and no peer-reviewed source located for this page evaluates whether a surge protector, a UV lamp or a smart thermostat pays for itself on a residential changeout. Anyone quoting a payback period for these items is quoting a sales estimate. What a homeowner can do is test each extra against the quote itself: is it a separate line with a separate price and its own written warranty, does it appear on all three bids or only the most expensive one, and did it appear in the conversation before the price was discussed or immediately after the homeowner flinched?

Surge protection has the clearest local logic of the three. Monsoon storms bring outages and reclosure events across the metro between June and September, and a modern variable-speed system carries a control board and an inverter drive that a 1990s single-stage condenser never had. That is an argument, not a measurement. Ask which device is being quoted by part number, whether it mounts at the condenser or at the electrical panel, what it is warranted to cover, and who pays if a board fails anyway — then price the same part independently.

UV and germicidal lamps are the extra that transplants best into desert sales scripts and fits the climate worst. The biological growth these devices target thrives on persistently wet coils and humid return air; Phoenix runs dry through most of the cooling season, with dewpoints climbing only during the monsoon weeks. If a lamp is quoted, ask whether it is aimed at the coil surface or the air stream, what the lamp replacement interval is, and what a replacement lamp costs — that is a recurring expense attached to what looks like a one-time line item.

A smart thermostat is the extra with a mechanism a Valley homeowner can actually operate. Time-of-use rates on both major utilities make pre-cooling ahead of the on-peak window worth scheduling, and both SRP and APS run thermostat demand-response programs that pay enrollment and seasonal credits. Program terms and eligible device lists change, so confirm them with the utility rather than the installer. Then compare the quoted price against retail for the same model number, since mounting and commissioning one during a changeout is minor labor.

The pattern worth watching across all three is bundling. When extras are welded into good-better-best tiers so that no single item can be declined, the homeowner has stopped comparing scope. The response is simple: ask for the same matched system quoted without them, and compare that number.

Should the lowest bid ever win?

Low bids win more often than reputation-based advice suggests, once scope has been normalized. If two documents name the same matched AHRI system, carry the same tonnage from the same load calculation, include the permit, include disposal, carry the same labor warranty and come from contractors in good standing, the cheaper one is simply cheaper. Phoenix homeowners who collect three bids on the same four-ton changeout routinely see thousands of dollars of spread on functionally identical equipment, and most of that gap is overhead, timing and scope rather than the hardware in the crate.

Low can be entirely legitimate. A smaller company carries less overhead per job. A contractor with that model already in stock avoids a special order. Work scheduled in the shoulder months rather than during the July emergency rush, when every Valley crew is booked and running overtime, is quoted differently. None of those conditions makes an installation worse.

Before accepting a low bid, verify the things that cost nothing to check. The Arizona Registrar of Contractors publishes license status, classification, bond information and complaint history at roc.az.gov, searchable by company name or license number, and the number on the bid should match the legal entity that will sign the contract. Confirm the permit is included rather than declared unnecessary. Get the labor warranty duration in writing. Ask for startup airflow and refrigerant charge readings to be recorded on the final invoice, and ask who pays for the return trip if either number lands out of range.

A low bid should lose when the price is low because something is absent. The common omissions in Valley quotes are consistent: no indoor coil model number, a tonnage copied off the old nameplate with no load calculation behind it, no permit, no crane line on a rooftop package unit that has to come off a roof and go back on, no line-set flush when the refrigerant changes, and nothing allowed for the attic duct connections that leak hardest in a 150-to-170-degree summer attic. Each omission returns later as a change order, and once it does, the comparison the homeowner made no longer describes the job being built.