McCUTCHEON & SONS
PHOENIX HVAC & PLUMBING
What to Check Before You Call a Tech
(602) 837-3630
It’s the middle of a Phoenix summer and the thermostat reads 80 while you set it to 74. The unit is running. The air is moving. It just isn’t cold. Before you search “ac not cooling phoenix” and call someone out, there are a handful of things worth checking yourself. Some of them cost nothing. A few take ten minutes. And knowing them saves you from paying a diagnostic fee for a fix you could’ve done for free.
Phoenix heat is hard on air conditioning. When a unit struggles here, the problem is usually one of a short list. Here’s how to work through it in order, from the cheapest fix to the one that actually needs a tech.
Rule out the free stuff first
Three things cause more “my AC isn’t cooling” calls in Phoenix than anything else, and none of them need a service call.
First, the air filter. Phoenix dust clogs a filter fast, and a clogged filter chokes airflow until the coil ices over. An iced coil stops absorbing heat, and suddenly the air coming out is warm. This is the single most common cause of AC blowing warm air, and the fix is a ten-dollar filter.
Second, the thermostat. If yours sits in direct afternoon sun or against a hot west wall, it reads a few degrees high and short-cycles the system, so the house never actually reaches the number you set.
Third, the breaker. If the inside blower is running but the outdoor condenser is silent, check the panel. A tripped breaker or a blown capacitor is a cheap, common fix. A silent outdoor unit is not always a dead system.
The three fixes that cost almost nothing
Start with the filter. Pull it and hold it up to the light. If you can’t see light through it, replace it. While you’re out there, check the outdoor condenser: it needs clearance to breathe. Monsoon debris, weeds, and dust built up against the coil make the unit work harder and cool less. Hose it off gently with the power off.
Then check the drain line. A clogged condensate line trips the float switch on a lot of newer systems and shuts the whole thing down, which reads exactly like a dead AC.
These are the fixes a good tech checks before quoting you a single part. Doing them yourself just means you’ve already handled the first fifteen minutes of the diagnostic.
Know when it’s really low refrigerant
“Low refrigerant” is the most misdiagnosed call in Phoenix. A system that leaks doesn’t use up refrigerant the way a car uses gas. Refrigerant lives in a sealed loop. If it’s genuinely low, there’s a leak, and that leak has to be found and fixed, not just topped off.
What techs actually find a lot of the time is a dirty coil or a restricted duct that makes the system act low on charge. The symptoms are identical: warm air, longer run times, higher bills. That’s why you want a diagnostic that checks the coil and airflow, not just the pressure gauge. A ten-minute coil inspection catches what a pressure reading alone will miss.
Know the difference between a real problem and Phoenix heat
Here’s a number that saves a lot of people a service call: a properly working AC can only drop the indoor temperature about 15 to 20 degrees below the outdoor temperature. If it’s 115 outside and your house is holding at 78 or 80, the unit may be working exactly as designed. That’s the physical limit, not a failure.
If it’s warmer than that indoors, the usual culprits in the Valley are a dirty or undersized coil, a refrigerant charge that has drifted low over the years, or the one most people miss: leaky attic ducts dumping your cold air into a 140-degree attic. Duct leaks are the reason two identical units cool two identical houses completely differently.
When to stop guessing and call
Work the list in order. If the filter is clean, the thermostat is fine, the outdoor unit is running, and the air is still lukewarm, that’s when it’s worth a real diagnostic. Anything beyond a simple filter or breaker fix, especially a refrigerant or coil issue, is not a DIY job. The tools to do it right aren’t in a homeowner’s garage, and guessing with a recharge you don’t need makes the real problem worse and more expensive later.
The right tech shows up, checks the coil and airflow, tells you whether it’s a cheap fix or a real repair, and gives you a straight number before they touch anything.
If your AC isn’t keeping up and you’d rather have a straight answer than a sales pitch, we’re one call away.
McCutcheon & Sons is a family-owned and operated HVAC and plumbing company serving Phoenix and the east valley: Gilbert, Chandler, Mesa, Queen Creek, San Tan, Tempe, Maricopa, Scottsdale, and Fountain Hills. Since 1999, one name on the truck, the quote, and the door. Licensed #339149. No commissions, no hidden costs, guaranteed work.
McCutcheon & Sons Air Conditioning and Plumbing · (602) 837-3630 · mccutcheonandsons.com · AZ ROC License #339149