Three quotes arrive for the same job, thousands apart. Same tonnage, same brand, very different numbers.
The gap is rarely the equipment. It is the work around it, most of which happens before the crew arrives and after the old unit is on the truck. That sequence tells you what you are actually comparing, and what to ask before signing. If you are still weighing AC repair against replacement, settle that first.
It starts with a load calculation, not your old nameplate
A replacement should not begin with someone reading the tonnage off the unit already in your yard.
That system may have been oversized the day it went in, and a fifteen-year-old decision does not account for windows you replaced, insulation you added, or shade that has grown over the west side. Correct sizing comes from a load calculation using square footage, orientation, window area, insulation values, ceiling height, and design temperature.
Why that matters to you: an oversized system cools the thermostat’s location fast, shuts off, and repeats. That is short cycling, and it causes the complaints people call about later, including rooms that never even out, lingering humidity, and a compressor worn out years early. Proper AC installation in Las Vegas starts with the calculation. A quote without one is a guess with a price attached.
The survey that shapes the quote
Before a number exists, someone should walk the entire system rather than glance at the condenser.
The walk covers whether your ductwork is sized for the new system, whether the line set can be reused, disconnect and breaker sizing, clearances around the outdoor unit, attic or closet access, and the thermostat wiring already in the wall.
This is where those three quotes diverge. One priced a new line set and a return-air modification. Another assumed both were fine. You are not comparing the same job, which is why the written scope matters more than the total. Since most replacements happen on short notice, ask about HVAC Maintenance during the quote rather than after the compressor quits.
Permits come before equipment
This is the step the lowest bid usually skips, and it is not optional in this valley.
Every jurisdiction here requires a mechanical permit to install or replace heating and cooling equipment, and a like-for-like changeout counts. Which office issues it depends on your address, since much of what people call Las Vegas is unincorporated Clark County while other parcels fall under the City of Las Vegas, Henderson, North Las Vegas, or Boulder City. Boundaries are irregular enough that it gets confirmed by address.
One Clark County detail catches people out. Residential mechanical permits are issued one appliance per permit, so a condenser and an air handler means two permits, not one.
Your contractor files it, not you. Refrigeration and air conditioning work in Nevada is licensed under the C-21 classification, and the licensed contractor pulls the permit. A quote that never mentions permitting is the one to question first.
Installation day
The old system comes out first, and the opening step is not what most people expect.
Refrigerant is recovered into a certified machine rather than vented, which federal rules require and which needs EPA Section 608 certification. Power comes off at the breaker and disconnect. Then the old condenser leaves the pad and the indoor coil or air handler comes out.
The new system involves more than reversing that. The pad gets checked or replaced, and the outdoor unit needs clearance on every side for airflow. Indoors, the coil rarely matches the old plenum exactly, so transition sheet metal gets fabricated to fit, which is faster when a contractor has its own sheet metal shop. Line sets are replaced or flushed, brazed under a nitrogen purge so scale does not form inside the tubing, and fitted with a new filter drier. Condensate line, float switch, and electrical connections follow, and the thermostat goes on last.
Expect one day for a straightforward changeout. Ductwork modifications, difficult attic access, or a second system push it longer.
Startup separates good installs from fast ones
Two crews can install identical air conditioning systems and leave you with different outcomes. This is where it happens.
Before refrigerant enters, the lines are evacuated to a deep vacuum measured on a micron gauge, pulling out moisture and air that would otherwise damage the system slowly from inside. Charge is then weighed in to the manufacturer’s specification rather than estimated from a gauge reading on a hot afternoon.
Then the numbers get verified. Superheat and subcooling confirm the charge. Static pressure and temperature split confirm the air side. Amp draw on the compressor and blower confirms nothing is straining. Ask to see those readings. A crew that packs up without taking any installed equipment rather than commissioning a system, and that shows up in year three, not week one.
Inspection and the paperwork that protects you
The job is not done when the truck leaves.
An inspector from the issuing jurisdiction verifies the work meets code, including the efficiency minimums that apply here, since Nevada sits in the Southwest region and carries higher requirements than the national baseline.
Manufacturer warranties generally require registration within a limited window, and late registration can cut the covered term substantially. Confirm who submits it and ask for proof. Coverage also assumes the system receives AC maintenance on schedule, so ask what the manufacturer expects before you need the warranty rather than while trying to use it.
What you should have before the crew pulls away
All of it is easier to collect on the day than six months later.
Model and serial numbers for both units. Written confirmation that the warranty was registered. A thermostat walkthrough, including how to set a schedule. The filter size and location, since a new system often takes a different size. The startup readings. And the permit number, so you can confirm the inspection passed rather than assume it.
Frequently asked questions
1) How long does an AC replacement take?
Usually one day for a straightforward changeout. Ductwork modifications, tight attic access, or two systems extend it. The inspection happens on a separate visit, and your system runs normally in the meantime.
2) Do I need to be home during the installation?
Someone should be. Crews need access to the indoor unit, the electrical panel, and the thermostat, and the end-of-day walkthrough is when you see the readings and learn the new controls.
3) Can I keep my existing ductwork?
Often, if it is sound and sized for the new system. Leaky or undersized ducts cap what new equipment can deliver, so you pay for capacity you never receive. That is why one quote may include ductwork another ignores.
4)What happens to my old system?
The contractor removes and disposes of it, with refrigerant recovered beforehand as federal rules require. The metal is generally recycled, and nothing is left behind in the side yard.
5)How do I know the new system was installed correctly?
Ask for the startup readings, the permit number, and proof of warranty registration. All three are hard to produce if the work was skipped, which makes them a better test than any promise made during the sales visit.
Conclusion
Most of a good replacement is invisible by the time you see it: the load calculation, the permit, the vacuum, the weighed charge, and the startup readings. The equipment matters less than the installation, and two identical systems can perform very differently depending on the care that went into them.
Infinity Heating and Cooling has replaced systems across the valley since 2012, with NATE-certified technicians, an in-house sheet metal shop, and Nevada license C21 number 0077587.
Call (702) 291-2000 or schedule a free in-home estimate to have your home evaluated and your options priced in writing.
