The HVAC Questions East Valley Homeowners Ask Us Most

Most Arizona systems are sized to hold roughly 75 to 78 degrees indoors at around 110 outside. Past that point, even a healthy air conditioner can fall a few degrees behind by late afternoon.

The better test is the temperature split. Air at a supply vent should read about 16 to 22 degrees cooler than air entering the return. If the split lands in that range and the house recovers after sunset, the system is running at its limit, not failing. If the split is low, or the house never catches up overnight, a refrigerant, airflow, or coil problem is likely and worth a diagnostic visit.

It should not need any. Refrigerant circulates in a sealed loop, so an air conditioner that is low has a leak somewhere, and topping it off without finding that leak only buys a few weeks or months.

Common leak points in desert systems include vibration-worn line sets, corroded evaporator coils, and valve cores on the outdoor unit. A proper refrigerant leak repair means locating the leak, sealing it, pulling a vacuum, and charging to the manufacturer's specification. On an older R-410A system, the repair cost weighed against the system's age decides whether it is worth fixing.

Ask how the failure was confirmed, why the compressor failed, what warranty still covers it, and how the installed price compares with a new matched system. Those four answers usually make the decision for you.

A compressor that died from a bad capacitor, low charge, or a burned contactor can fail again if that cause stays in place. Many Trane and Lennox compressors carry 10-year parts coverage when the system was registered, though labor and refrigerant are usually extra. On a system past 12 years old, the math often favors a new air conditioner installation. On a newer registered unit, a warranty compressor swap can make good sense.

Usually the failed part was replaced, but the reason it failed was not addressed. Capacitors, contactors, and fan motors often fail from heat, voltage problems, or airflow strain that is still there after the repair.

A capacitor that keeps failing may be undersized for its motor or cooking inside a condenser choked with dust. A contactor that keeps pitting can point to low voltage or short cycling. Ask the technician what caused the first failure, not only what broke. If the only answer is that the part wore out, ask what wore it out, because that is the repair that stops the repeat visits.

Your existing R-410A system can still be repaired and recharged. The change applies to new equipment, and new residential split systems installed from January 1, 2026 onward must use lower-impact refrigerants such as R-454B or R-32 (verified September 22, 2026).

R-410A production is being phased down under the federal AIM Act, so its price has climbed and will keep climbing. That hits hardest on a leaking older system that needs repeated charges. New R-454B equipment cannot simply be paired with an old R-410A coil, which is why partial system swaps are rarely an option now. EPA-certified technicians at Accurate Air service both refrigerants.

Often more than homeowners expect. The U.S. Department of Energy estimates typical duct systems lose 20 to 30 percent of the air they move, and in a Tempe attic that tops 140 degrees in July, that cold air is simply gone.

Leaks at plenum connections, crushed flex runs, and disconnected register boots are common in older Tempe ranch homes and established Mesa neighborhoods. The symptoms look like an AC problem: rooms that never cool, dusty registers, and high bills from a system that tests fine. A duct inspection belongs before any talk of a bigger unit, because a larger air conditioner pushing air into the same leaks fixes nothing.

That is normal. A heat pump delivers supply air around 90 to 100 degrees, while a gas furnace blows 120 degrees or hotter, so the air feels cool against your hand even while it is warming the house.

The better test is whether the home holds the thermostat setting. Heat pumps run longer, gentler cycles than furnaces. If the house slides below setpoint on a 40-degree night, or the vents blow room-temperature air, the reversing valve, refrigerant charge, or defrost controls need a look.

It is almost certainly running a defrost cycle. When frost forms on the outdoor coil, the system briefly reverses to melt it, and the steam you see is that frost clearing off.

Defrost is rare on the Tempe valley floor but common on winter mornings in Cave Creek, Carefree, and Fountain Hills, where higher elevation brings frost. A normal cycle lasts a few minutes. If the coil stays iced over, ice builds on top of the cabinet, or the fan never restarts, a defrost board, sensor, or low charge may be at fault. Never chip ice off the coil.

Aux heat is backup electric heat that switches on automatically when the heat pump needs help. Emergency heat forces those strips on and shuts the heat pump off, so use it only when the heat pump has failed.

Heat strips cost far more to run than the heat pump itself, so a thermostat showing "aux" for hours on a mild East Valley night is a warning sign. Common causes include an aggressive thermostat schedule, a struggling heat pump, or wiring mistakes after a thermostat swap. If you have been running emergency heat to get by, schedule a repair before the next SRP bill lands.

Yes. In cooling mode, a heat pump dehumidifies the same way a central air conditioner does, pulling moisture out of the air as it crosses the cold indoor coil and draining it outside.

How well it does that depends on run time. An oversized heat pump that cools the house in ten minutes and shuts off leaves sticky air behind during a humid July or August monsoon stretch. Variable-speed models run longer at low speed and pull more moisture. If your home feels clammy even when it is cool, the sizing or fan settings are the likely issue, not the refrigerant.

Often, yes. The setup is called dual fuel. The heat pump handles all the cooling and most of the heating, and the gas furnace takes over only on the coldest nights, based on an outdoor temperature setting.

It works best when the furnace is in good shape with a compatible blower and control board. In Tempe, Chandler, and Mesa, a furnace in a dual-fuel system may only fire a handful of nights a year, which stretches its life. The indoor coil must match the new heat pump, and a load calculation confirms the size before anything is ordered. Our heat pump installation team can check whether yours qualifies.

A dusty, toasty smell for the first 15 to 30 minutes of the season is normal. Dust settles on the burners and heat exchanger during the months the furnace sits idle, and it burns off at startup.

Swapping the filter before the first cold night cuts the smell and protects the blower. The odor should fade within an hour and not come back. If it lingers, smells like hot plastic or rubber, or comes with smoke, shut the system off and treat it as the burning-smell emergency at the top of this page.

With evidence you can see. Ask for photos or camera footage of the crack, combustion readings, and carbon monoxide measurements, and ask which of those tests showed the problem.

A cracked heat exchanger is a valid safety reason to retire a furnace, and it is also one of the most common scare tactics used to sell one. Many manufacturers cover heat exchangers for 20 years or longer, so check the warranty before paying for a new unit. If the diagnosis rests on a hunch, get a second opinion.

The furnace is shutting itself down to prevent a dangerous condition. A rollout switch trips when flames escape the burner area, often from a blocked flue or cracked exchanger. A limit switch trips when the furnace overheats, usually from poor airflow.

Limit trips commonly trace to a clogged filter, closed supply registers, or a weak blower, all fixable. Rollout trips are more serious and should never be reset repeatedly or bypassed. In older Tempe homes with attic furnaces, a disconnected or damaged vent pipe is a frequent culprit. Leave the furnace off after a rollout trip and have it inspected before the next use.

Usually not for heating savings alone. Most East Valley homes run the furnace only a few weeks a year, so the gas saved by a 95 percent furnace over an 80 percent model rarely pays back the higher installation cost.

The exceptions are homes already set up with condensing furnaces and PVC venting, and foothill homes in Cave Creek or Carefree that heat more often. High-efficiency models also need a condensate drain, which adds one more clog point in a hot attic. For many Tempe homes, a heat pump or a dual-fuel setup is the stronger efficiency move.

A unit sized for the room, an indoor head placed for good airflow, a pressure-tested and vacuum-evacuated line set, a condensate line that slopes downhill, a dedicated electrical circuit, and a startup test with recorded readings.

The shortcuts to watch for are line sets that were never evacuated, flare fittings tightened by feel instead of torque spec, and condensate lines that run uphill and leak down the wall. In Arizona, the outdoor unit also needs clearance from reflected heat off block walls.

The most common failures are undersized units, refrigerant leaks at field connections, and wiring mistakes. Many manufacturers also limit or void the warranty unless a licensed contractor installs the system.

In a detached casita that sees 120-degree afternoons, an undersized DIY unit runs nonstop and never catches up. SRP's Cool Cash rebate also requires an Arizona-licensed installing contractor and excludes garages and other non-habitable spaces (verified September 22, 2026).

A single-zone unit cools one space well, but conditioned air rarely travels far past a doorway. For several rooms, a multi-zone system connects two to five indoor heads to one outdoor unit, each with its own control.

The right choice depends on the layout. An open great room might be served by one head, while a back bedroom down a hallway will not be. Multi-zone systems save wall space outside, but if the single outdoor unit fails, every zone goes down at once. For a whole-home ductless setup, sizing each head to its room matters more than total tonnage.

Usually, yes. Casitas, enclosed patios, and garage conversions are hard to reach with existing ductwork, and a mini-split cools them without adding load to the main system.

Extending main-house ducts into an Arizona room often starves the rest of the home of airflow, especially when the addition has single-pane glass facing west. A dedicated ductless unit lets that space run on its own schedule. Check HOA rules first, since many Scottsdale and Gilbert communities regulate where outdoor condensers can sit and how they are screened.

Fine desert dust, monsoon haboobs, and a long cooling season push more air, and more dust, through the filter each month than in most of the country. A dirty filter usually means it is doing its job.

Homes near construction in fast-growing areas like Queen Creek, homes beside open desert, and homes with pets load filters fastest. During summer, many East Valley homes need a new 1-inch filter every 30 days. If a filter clogs in two weeks, look for gaps around the return grille or leaky return ducts in the attic pulling in dust. Our air filtration systems page covers upgrades.

It can. A MERV 13 filter catches smaller particles but also resists airflow more, and many homes with small return grilles cannot handle that resistance in a thin 1-inch filter.

Restricted airflow can freeze the evaporator coil and overheat the blower motor, the opposite of what you want in July. A 4-inch or 5-inch media cabinet delivers high filtration with far less resistance. A technician can measure static pressure to show what your system tolerates. For most homes, a MERV 8 to 11 filter in the right size strikes a strong balance.

It can if the wrong tools are used. Flex duct has a thin inner liner that stiff rotary brushes can tear, so cleaning it calls for gentler methods like soft whips and negative-pressure vacuums.

Many Tempe and Mesa homes built from the 1990s onward run flex duct through the attic, and a lot of it is past its prime. If the liner is already brittle, cracked, or crushed, cleaning is the wrong fix and replacement is the better spend. A pre-cleaning inspection should tell you which you have. Be wary of cheap duct cleaning offers that skip it.

Installed inside the air handler and aimed at the coil and drain pan, UV lights help control mold and bacterial growth on those damp surfaces. Properly installed, the light never reaches anyone in the home.

UV works best on the coil, not on fast-moving air, so claims about killing every airborne germ deserve skepticism. Bulbs lose output and need replacing about once a year. Accurate Air inspects HVAC equipment for visible mold but does not perform mold remediation, so a larger mold problem goes to a remediation specialist. Our UV purification systems page explains placement.

Sometimes both, in different seasons. Winter indoor humidity in the East Valley can drop below 20 percent, while monsoon weeks can push indoor air above 60 percent in tightly sealed homes.

A whole-home humidifier helps with dry skin, static shocks, and cracking wood floors or instruments in winter. Monsoon stickiness is more often a sizing or airflow issue with the AC, which a technician should rule out before you add a dehumidifier. A technician can check humidity levels during any service visit.

Treat it as urgent, log the time of the call, and get a technician dispatched the same day. Arizona's landlord and tenant law requires landlords to keep supplied air conditioning in working order.

That requirement sits in A.R.S. § 33-1324, and some cities, including Phoenix, add indoor temperature standards of their own, so check the code where your property sits. While waiting on repairs, some managers provide portable units or temporary lodging for at-risk tenants. The best fix is prevention: tracking unit ages and maintenance history before summer keeps five emergencies from landing in the same July week.

Scheduled visits with a written scope, filter changes on a set cadence, coil cleaning, belt and motor checks, refrigerant and electrical tests, and a written report after every visit documenting each unit.

The report is what separates a useful agreement from a sticker on the unit. For retail stores, offices, and rental portfolios, it gives you a repair history, age data for budgeting replacements, and proof of maintenance for warranty claims. Ask how emergency calls are prioritized for agreement customers and whether pricing runs per unit or per site.

Rooftop units sit in direct sun on hot roofs, so they run hotter and cycle harder than ground-level equipment. Dust-packed condenser coils, heat-damaged capacitors, and worn belts are the usual failures.

Roof surfaces in Tempe and Mesa can pass 150 degrees in July, which raises condenser pressures and strains compressors. Coil cleaning before summer, belt checks, and capacitor testing catch most failures before tenants or customers notice.

Keep one record per unit with the model, serial number, install date, filter size, and every service visit. The hard part is keeping it current, which is where an HVAC partner that tracks it for you earns its keep.

Accurate Air works with a property manager overseeing five East Valley complexes, tracking when individual units are due for maintenance and flagging aging equipment before it fails. That record turns HVAC from surprise emergencies into a planned budget line.