Author: 75degreeac

You pull the panel off your air handler expecting to find nothing wrong, and instead you find the evaporator coil wrapped in ice like a bad science experiment. This is one of the most common calls 75 Degree AC gets between May and August. If your AC keeps freezing Houston-style, on repeat, every few days, this is exactly why, and exactly where the line sits between something you can check yourself and something that needs a licensed tech. A homeowner turns the system off, lets it thaw, turns it back on, and it runs fine for a few hours before freezing again. By the third cycle, the compressor has started swallowing liquid refrigerant it was never built to handle, and a $250 service call is quietly turning into a $3,500 repair.  What’s Actually Happening When Your AC Freezes Up An air conditioner doesn’t make cold air out of nothing. It moves heat. Refrigerant flows into the indoor evaporator coil, drops in pressure, and boils into a gas, and that phase change is what pulls heat out of the air your blower pushes across it. Under normal conditions the coil sits around 40°F. Two things have to stay balanced for that number to hold: enough warm air moving across the coil, and the correct volume of refrigerant inside it. When either one slips, even slightly, coil temperature falls below 32°F. Houston’s humidity means there’s always moisture sitting on that cold metal, and instead of dripping into the condensate pan, it freezes on contact. Give it twenty minutes and you’ve got a thin frost layer. Give it two hours and the coil is a solid block, and your blower is now pushing air against a wall of ice instead of through it. Here’s the part most homeowners miss: the ice isn’t the damage. The damage happens after. Liquid refrigerant that should have boiled off in the coil slips through unchanged and heads straight for the outdoor compressor, which is built to compress gas, not liquid. That’s called slugging, and it bends valve plates, shears motor windings, and cracks discharge reeds. A compressor that’s absorbed two or three freeze-thaw cycles rarely comes back to full life. Run it through a week of that and you’re compressor shopping. Why AC Freezing Up Is So Common Here Specifically Ask a tech in Phoenix why AC freezing up happens and you’ll get a shorter list than you’d get AC keeps freezing Houston. Three things stack up against us specifically. The humidity load. Houston sits above 70% relative humidity for most of May through October. A 3-ton system might be pulling 18 pints of water out of the air per hour on a wet June afternoon, and dehumidifying that air is more than half the system’s actual workload. Anything that disrupts drainage or airflow, even a dirty filter, freezes that moisture before it ever reaches the drain pan. Attic-mounted equipment. Around 95% of Houston homes run the air handler out of the attic, where summer temperatures regularly climb past 130°F. That heat dries out duct mastic and warps flex duct over time, which means air leaks out of the supply plenum before it ever reaches the coil. We’ve measured static pressure in older Memorial-area systems running nearly double the manufacturer spec, and that kind of restriction is exactly what tips a marginal system into a freeze. Grid-related airflow dips. During peak summer demand hours, typically 4 to 8 PM in July and August, brief voltage sags can cause a blower’s ECM motor to under speed. Less air across the coil while the compressor keeps calling for cooling pushes coil temperature down fast, and we’ve traced overnight freeze-ups in Cypress and Katy homes back to exactly this. Layer any of those on top of a refrigerant charge that’s already 8-10% low from a leak nobody’s noticed, and the freeze is basically scheduled. It’s why a system that would freeze in August in Dallas freezes in late May here. The Real Causes Behind an AC Keeps Freezing Houston Pattern After years of frozen-coil tickets across the metro, the causes break down fairly predictably. A dirty filter or filthy coil (the biggest one, by far) This is the only cause a homeowner can sometimes catch without a tech. A filter that’s been sitting for six months in a pet household turns into a solid wall, and less air across the coil means a colder coil. In homes with two cats, a 1-inch filter needs changing every 60-75 days, not twice a year. Beyond the filter, a coil that hasn’t been cleaned in years grows a film of dust that chokes airflow from the other side. Low refrigerant from a slow leak Refrigerant doesn’t wear out or evaporate on its own. If a system is low, it’s leaking, usually from a corroded Schrader valve at the service port, pinhole corrosion inside the coil itself, or a crack where the line set enters the attic. A 3-ton system that’s just 12 ounces low on a 6-pound charge will start freezing once runtimes stretch into May. Recharging without finding the leak first just delays the same call by a few weeks, this is the exact diagnostic gap our AC leak repair process is built to close. A failing blower motor A worn ECM module, a tired PSC motor bearing, or a blower wheel caked in dust all reduce the CFM crossing the coil. Homes with original 2008-2010 era blower motors are especially prone to this, since these motors lose efficiency gradually for a couple of summers before they fail outright. Blocked or closed ducts A damper someone closed and forgot about, a box stacked against a return grille, pet hair sealing off a return that hasn’t been vacuumed in two years. We always check the return path before touching refrigerant, because a full recharge on a duct-restricted system just freezes again in a week. Thermostat habits Setting the thermostat 8°F below room temperature on a humid afternoon forces runtimes past 90 minutes

If your air conditioner runs all afternoon and your house still feels warm, you’re not imagining it. The signs AC overworking Houston homeowners describe to us every summer almost always follow the same pattern: long run times, climbing bills, and a system that never quite catches up with the heat. At 75 Degree AC, we walk into these calls constantly between June and September, and in nearly every case the warning signs were visible weeks before the system finally gave out. This guide breaks down exactly what to look for, why Houston’s climate makes it worse than almost anywhere else, and what actually fixes it including a cause most articles skip entirely: an overcharged refrigerant system. Why Houston Heat Pushes AC Systems Past Their Limit Houston doesn’t have typical summer weather; it has sustained, humid, triple-digit heat index days that stretch on for months. From June through September, outdoor temperatures regularly sit at 95°F or higher, and the urban heat island effect around inner-loop neighborhoods pushes ambient temperatures even higher than surrounding suburbs. That means residential AC systems aren’t just fighting heat for a few weeks a year they’re fighting it nearly nonstop. A few local factors make this worse: Southwest-facing windows catch direct afternoon sun and drive up solar heat gain, forcing the system to fight a rising heat load every afternoon. Metal roofing, common in newer Houston construction, transfers heat into attic spaces faster than traditional shingles, which radiates down into living areas. Undersized systems are common in fast-built suburbs like Pearland, League City, and Friendswood, where units were sized for speed during construction booms rather than an accurate load calculation. Gulf humidity in northeast corridor neighborhoods like Humble, Kingwood, and Atascocita forces systems to run longer cooling cycles just to pull moisture out of the air. Any one of these factors is enough to strain a system. Combined, they’re exactly why signs AC overworking Houston issues show up so much more often here than in milder climates. Top Signs of AC Overworking in Houston Most AC failures don’t happen without warning. The system tells you something is wrong long before it quits, you just have to know what to look and listen for.  Our technicians carry brand-specific and universal parts on every call, so most repairs including AC compressor repair are completed the same day. 1. The AC Runs Constantly and Never Reaches the Set Temperature A healthy AC cycles on and off throughout the day. If yours runs nonstop and the house still doesn’t hit your thermostat setting, the system is working at full output but losing the fight against the heat load. Technicians measure this with Delta T the temperature difference between the air entering and leaving the coil. A healthy Delta T sits between 14°F and 22°F; anything outside that range is a clear signal something inside the system is struggling. 2. Your Electric Bill Spikes Without an Obvious Reason An AC pulling more amperage than it should show up directly on your Center Point Energy bill. Time-of-use rates already make afternoon cooling more expensive, so when a strained system runs longer hours on top of that, the cost compounds fast. If your bill jumps well beyond the normal seasonal increase, that’s one of the earliest measurable signs AC overworking Houston homes experience. 3. Warm or Lukewarm Air Comes From the Vents If the system is running but the air isn’t cold, something is blocking proper heat transfer, low refrigerant, a dirty evaporator coil, or a failing compressor. This is confirmed with superheat and sub cooling readings, which tell a technician exactly where the refrigerant cycle is breaking down. 4. The System Is Short Cycling Short cycling turning on, running briefly, shutting off, then restarting minutes later is one of the most damaging patterns an AC can fall into. Every start-up stresses the compressor and motor windings. It’s often caused by an oversized unit, low refrigerant, or restricted airflow from a dirty coil, but it can also be caused by the opposite problem: too much refrigerant (more on that below). 5. The Circuit Breaker Keeps Tripping A breaker that trips when the AC kicks on means the system is pulling more amperage than the circuit can safely carry. This usually points to a compressor or fan motor overheating under strain, and it’s not something to keep resetting and ignoring repeated trips accelerate motor winding failure. 6. Strange Noises From the Outdoor or Indoor Unit Banging, grinding, rattling, or squealing sounds mean mechanical components are failing under load. A seized condenser fan motor, for example, stops heat from properly leaving the outdoor unit, which pushes the compressor into overheating territory. 7. Some Rooms Are Noticeably Hotter Than Others Uneven cooling is usually a static pressure problem inside the ductwork. The system runs longer trying to satisfy the thermostat but never balances airflow properly across every room, which is especially common in southwest-facing rooms that absorb the most afternoon heat. 8. Ice Forms on the Refrigerant Lines or Indoor Coil Ice buildup is a strong indicator of restricted airflow or a refrigerant charge problem. Homeowners often mistake this for the system “working too well” in reality, it means the coil temperature has dropped low enough to freeze condensation, and the system is now cooling less efficiently than before the ice formed. 9. Musty, Burning, or Chemical Odors From the Vents An overworked system that runs hot for extended periods can develop burning smells from electrical components or musty odors from moisture buildup in the ductwork. Either smell is a signal to shut the system off and have it inspected before continuing to run it. 10. The System Is Old and Still Running Nonstop Most AC systems are rated for around 15 years of service life. In Houston’s extreme heat, a system that runs overworked without regular maintenance can fail in as little as 8 to 10 years. If your unit is already past the 10-year mark and showing any of the signs above, it’s worth

Every May, right before Houston’s first real 95°F stretch, our phones start ringing with the same complaint: “my AC won’t start, it’s just humming.” Nine times out of ten, the culprit is a $40 part sitting inside the outdoor unit. Catch it early and it’s a quick, affordable repair. Ignore it through a few more hot weeks and that same $40 part takes a $2,500-$4,000 compressor down with it. That part is the run capacitor, and recognizing AC capacitor failure symptoms early is the single biggest money-saver in residential HVAC. Here’s what’s actually happening inside that little can, the exact symptoms to watch for, and what separates a $200 fix from a $400 emergency call. What Is an AC Capacitor? Your outdoor condenser has two motors that need a serious kick to get moving: the compressor and the condenser fan. Neither one can start on line voltage alone; they need a short, powerful burst of stored energy first. That’s the capacitor’s job. Picture it as a tiny battery that only lives for about half a second at a time. Inside the can, thin metal plates sit separated by an insulating film. That film the dielectric charges up and dumps energy into the motor the instant your thermostat calls for cooling. Most residential systems use a single “dual-run” capacitor that handles both jobs in one can. You’ll see two numbers stamped on the side, something like “45/5 µF.” The first number is the compressor rating, the second is the fan. AC Capacitor Failure Symptoms A failing AC capacitor can prevent your air conditioning system from starting properly, reduce energy efficiency, and place unnecessary strain on critical components such as the compressor and fan motor. Recognizing the early warning signs of capacitor failure can help you avoid unexpected breakdowns, higher utility bills, and costly repairs. Below are the most ac capacitor failure symptoms homeowners should watch for. Why Houston Capacitors Fail Faster Than Almost Anywhere Else Heat is the single biggest killer of run capacitors, and the dielectric film degrades exponentially faster as ambient temperature climbs. National Weather Service data for Houston shows the metro averages 99 days a year above 90°F and 32 days above 95°F, well ahead of Dallas (roughly 85 days above 90°F) and nowhere close to a city like St. Louis (about 38). It’s not just outdoor air temperature either. A condenser sitting in direct sun on the south or west side of a house can push internal capacitor temperature past 140°F on a July afternoon. Voltage sags and brief brownouts are common between 4 PM and 8 PM in July and August. Every time the system shuts off and restarts, the capacitor absorbs the full inrush load again. A capacitor in a milder climate might see two clean start cycles a day. One in Cypress or Spring during a conservation event can see six or seven in a single afternoon. Seven AC Capacitor Failure Symptoms to Watch For These are the bad AC capacitor symptoms we see most often on Houston AC capacitor failure symptoms service calls, in the order homeowners usually notice them. 1. The Unit Hums but the Compressor Won’t Start This is the textbook sign. You hear the contactor click and a low electrical hum from outside, but the compressor never spins up. After 30–60 seconds, an internal overload trips and it goes quiet, then tries again a few minutes later. Each attempt adds more wear. 2. The Outdoor Fan Is Slow, Sluggish, or Not Spinning at All The fan side of a dual-run capacitor can fail on its own, independent of the compressor side. If the fan isn’t moving while the compressor runs, don’t let it sit without airflow across the coil. The compressor can overheat within five to ten minutes. 3. The Breaker Trips Shortly After Startup A weak capacitor still tries to start the compressor but pulls excessive amperage doing it, sometimes double the rated load. If you’re resetting the breaker more than once a week, stop resetting it and get it checked. Repeated trips wear down both the breaker and the compressor windings. 4. Cooling Feels Weaker and the Electric Bill Is Creeping Up A marginal capacitor lets the system keep running, just less efficiently. The compressor works harder and longer to hit the same temperature. We’ve seen Houston homes where a $35 part was quietly adding $80–90 a month to the electric bill, and the homeowner just assumed the system was “getting old.” 5. A Buzzing or Chattering Sound at Startup Listen right at the outdoor unit when the system first kicks on. A healthy start is one clean click followed by the compressor and fan spinning up together. A failing capacitor sounds more like a stutter or buzz as the contactor keeps trying to find enough kick to start the motor. 6. The AC Turns Off on Its Own Mid-Cycle If the system shuts down before it reaches your thermostat setting not because it satisfies the call, but randomly a degrading capacitor is one of the most common causes. 7. A Visible Bulge, Oily Residue, or Rust at the Terminals With the disconnect pulled, you can look at the can itself. A domed top or wet residue means it’s already past failure. This is also the point where DIY should stop: a capacitor can hold a dangerous charge for several minutes after power is cut, even when it looks “dead.” If you’re seeing even one of these signs of a bad capacitor on your AC unit, get a meter on it within days, not weeks. A AC capacitor failure symptoms testing at 80% of spec might last another week or it might not survive the next hot afternoon. What a Real Capacitor Diagnostic Looks Like When a 75 Degree AC technician gets a no-cool call, the first stop is the thermostat confirming the call for cooling and ruling out something simple. About half of May’s “AC is dead” calls turn out to be thermostat issues, not the condenser at

Walk into any HVAC supply house in Houston this spring and the box stacks tell the story. R-410A cylinders in the back, marked up, fewer of them every month. R-454B up front, in the new green-banded jugs, sitting next to the Carrier Puron Advance, Trane TruComfort, and Lennox EcoLogic literature. On January 1, 2025 the EPA’s AIM Act stopped manufacturers from charging new residential AC equipment with R-410A. Eighteen months in, we get the same homeowner question on roughly one in three replacement quotes: Does this mean I have to swap my system? The answer is no, and the math behind the no is the part most contractors won’t walk you through. What the AIM Act Actually Did (And Didn’t Do) The American Innovation and Manufacturing Act of 2020 gave the EPA authority to phase down hydrofluorocarbon (HFC) refrigerants, the family R-410A belongs to. The rule that landed on January 1, 2025 was narrow on purpose: manufacturers can no longer build new residential split-system or packaged AC equipment that uses R-410A. That’s the bright line. Equipment that came off the line in 2024 or earlier is still legal to sell from inventory through mid-2026. It’s also still legal to install, own, and service. The AIM Act did not ban R-410A possession, did not ban R-410A service, and did not ban the refrigerant itself from being produced for the existing installed base. What the rule replaced R-410A with is two refrigerants: R-454B as the primary residential successor (Carrier, Trane, Lennox, Goodman) and R-32 as the secondary (Daikin, some Mitsubishi mini-splits). Both are A2L class under ASHRAE 34, meaning mildly flammable. Both require equipment specifically engineered for A2L handling, including sealed metering devices, gas-tight cabinets, and factory-installed leak detection on the indoor coil section. R-454B and R-32 cannot be retrofitted into an R-410A system. Pressures differ between the new refrigerants (R-454B sits close to R-410A; R-32 runs higher), the seal materials change, and the safety logic adds active leak detection. Switching refrigerants means buying a matched new system, not a refill. In the May 2026 install run we’ve been on through the Energy Corridor, Memorial, and Spring Branch, every replacement we quote is now an R-454B match. Of those, roughly 70% are homeowners replacing on schedule. These units are typically in the 12 to 15 year range, past the run-hour-adjusted lifespan curve for Houston. The other 30% are leak-driven replacements where the math on a $1,100 R-410A recharge plus parts pushed the conversation toward a new system. Neither group is replacing because of the AIM Act. The Act changed what arrives on the truck, not whether the truck shows up. The most useful framing we’ve found: think of it the way you’d think about gasoline grade changes. Your existing engine still runs on the fuel it was designed for, even after the new grade hits the pump. The new fuel only matters when you’re buying a new engine. R-454B works the same way. It touches your wallet at the moment of replacement, not before. How Houston Conditions Shape the R-454B Transition Houston AC systems run roughly 2.3 to 2.7 times harder than the national average. NCEI’s 1991–2020 normals for Houston Intercontinental show 102.4 days per year at or above 90°F, 3.5 days at or above 100°F, and an annual relative humidity averaging 74.7%, closer to 90% on summer mornings. That run-hour math, originally compiled for our replacement-timing analysis, translates directly to how the refrigerant transition plays out here. Leak frequency is the biggest factor. The Gulf Coast’s combination of salt-laden air pushed inland from Galveston Bay (especially in Clear Lake, Kemah, La Porte, and east Pasadena ZIPs like 77571 and 77591), high run hours, and aggressive thermal cycling means refrigerant leaks show up earlier here than in dry climates. When a leak shows up on an R-410A system in 2026, you’re looking at $25 to $45 per pound for the refrigerant alone, against $8 to $12 per pound in 2022. A standard 6 to 10 pound recharge on a residential 3-ton unit is now a $900 to $1,400 conversation. That’s the part of the AIM Act that touches Houston wallets, and it touches them faster here than in Denver or Phoenix. Attic installs matter next. Roughly 60% of Houston single-family homes have attic-mounted air handlers, a layout that’s nearly unheard of in cooler markets. A2L refrigerant equipment ships with mandatory leak detection at the indoor coil section under UL 60335-2-40 safety requirements. In a Houston attic that hits 130°F+ from May through September, that detector sits in conditions tougher than the same component would face anywhere else in the country. Reputable installers in 2026 are routing the leak-detection signal cabling carefully, sealing junction boxes against vermin and humidity intrusion, and verifying the detector cold-start logic in the same place the homeowner will see the system fail first. The permit and code piece closes out the Houston angle. The City of Houston requires a Mechanical Permit for any AC condenser or air handler replacement under Chapter 8 of the city code, pulled by the licensed contractor at roughly $92 base plus $10 per $1,000 of valuation. With A2L equipment, the inspector is checking three items our office sees flagged on lazy installs: clear marking of the refrigerant type on the cabinet exterior, verification that the air handler has the factory-installed leak detection wired and tested, and confirmation the line set diameter matches the manufacturer’s R-454B spec (R-454B runs slightly different from R-410A on optimum line sizing for long runs). If a contractor skips the permit to save you $400, you’re inheriting their inspection liability and a potential homeowner-insurance disclosure problem at resale. What Changes For You: A Homeowner Checklist Most homeowners reading this won’t be replacing their AC this year. For those who are, or for those who’ll get there over the next 24 months, here’s what actually changes. Your existing R-410A system stays in service. Don’t let a sales rep tell you it’s been “outlawed” or “phased out of legality.” Both phrases are false. The refrigerant is on every

Your AC is somewhere between 8 and 18 years old. A contractor just told you it’s “on borrowed time.” Or a friend in Dallas told you theirs lasted 20 years and yours should too. So which is it? Here’s how long do AC units last in Houston the honest answer: a central air conditioner in Houston typically lasts 10 to 15 years, compared with 15 to 20 years nationally. The shorter lifespan is driven by run-hours. Houston ACs log roughly 2,800 to 3,200 cooling hours a year, about 2.3× the national average of 1,200, across a 7-month cooling season with average humidity near 75% (NWS Houston Climate Normal 1991–2020). That’s the math nobody shows you on a sales call. Below, we work through it, along with the 50% rule, the $5,000 rule, the 2026 refrigerant transition, what CenterPoint will actually rebate, and the federal credit that quietly expired on December 31, 2025. The Short Answer (Houston-Specific) Houstonians should expect their central air conditioners to last 10-15 years on average compared to 15-20 nationally; run-hours rather than equipment quality are driving this difference in lifespan; Houston ACs usually log around 2,800-3200 cooling hours annually (2.3x the national average of 1,200). Inverter systems (Carrier Infinity 26, Trane XV20i or Lennox Signature SL18XC1) with annual maintenance may reach year 15 by extending this further; entry-tier systems without tune-ups may reach year 10 or earlier before major repairs of $1500+ require further consideration due to run-hour differences before signing checks or writing checks against major repair quotes that require repair estimates from repair shops (NWS Houston Climate Normals 1991-20). 75 Degree AC has been running Houston repair-vs-replace assessments since 2016 under master license TACLA72152E, and we put both the repair number and the replacement number on the same written quote. For a written repair-vs-replace assessment with a Manual J load calculation, call (713) 598-2737. That’s a five-year haircut against the national average, and it’s not because Houston techs install systems badly. It’s because the equipment runs more. A lot more. The next section is the math we wish more contractors would explain at the kitchen table. If you’re already past year 12 and a major repair quote just landed in your lap, jump to Repair vs Replace. That’s the section that decides it. The Run-Hour Math Nobody Shows You Most lifespan articles tell you “ACs in Texas last 10-15 years” and stop there. The number is right; the reason it’s right gets glossed over. How a Houston AC Logs 2,800+ Cooling Hours a Year Houston averages 102.4 days at or above 90°F every year, with annual relative humidity around 74.7%, which puts it among the most cooling-stressful climates in the United States (NWS Houston/Galveston Climate Normals, 1991–2020). The cooling season runs April through October, roughly seven months, with peaks of 109°F in record summers. The math works out cleanly. Seven months × roughly 30 days × about 14 active cooling hours per day ≈ 2,940 hours of compressor runtime annually. A unit in Chicago, by comparison, logs around 1,100–1,200 hours. Same equipment, same model number, same install quality, and 2.3× to 2.7× the wear in Houston versus the national average. Side-by-side, the wear math on identical equipment by city: Metro Annual cooling hours Cooling season length Wear multiplier vs national Houston, TX 2,800–3,200 7 months (April–October) 2.3×–2.7× Phoenix, AZ 2,500–2,900 7 months (April–October) 2.1×–2.4× Dallas, TX 2,000–2,300 6 months (May–October) 1.7×–1.9× Atlanta, GA 1,600–1,800 6 months (May–October) 1.3×–1.5× National average 1,100–1,200 4–5 months 1.0× (baseline) Chicago, IL 1,000–1,200 4 months (June–September) 0.9×–1.0× Boston, MA 800–1,000 3–4 months (June–September) 0.7×–0.8× A 12-year-old Houston condenser at Houston run-hours has logged the equivalent of about 27 calendar years of wear on a national-average unit. That’s the gap behind the lifespan difference, and the reason why a “still has life in it” call in Atlanta is not the same call in Houston. 10,000 Compressor Cycles vs Roughly 4,000 in Cooler Climates Hours are only half the story. The other half is cycles, meaning every time the thermostat triggers the compressor on. A typical Houston AC starts and stops about 10,000 times a year. A moderate-climate unit might cycle 4,000–6,000 times. Why does that matter? Every start spikes inrush current through the run capacitor and contactor. Those are the two parts that fail most often on aging Houston systems, and on the storm-day surge events that follow CenterPoint outages, the capacitor takes the brunt. (We wrote a whole piece on the capacitor failure pattern after Houston storms. If your unit is past 8 years, it’s worth a read.) Variable-speed inverter compressors (the ones in 16+ SEER2 systems) modulate output instead of cycling fully on and off. That’s a real engineering advantage in Houston, but it’s only relevant when you’re buying a new system anyway. Your existing single-stage compressor doesn’t get to convert. Why a 12-Year-Old Houston AC Is Closer to a 20-Year-Old Chicago AC If you multiply calendar age by the Houston run-hour multiplier (~2.3), a 12-year-old Memorial-area condenser has logged roughly 35,000 cooling hours, which is the operating equivalent of a unit that’s been on a Chicago suburban wall for about 29 years. That’s the framing competing contractors use when one says “still has life in it” and the other says “replace now.” Both can be technically correct. They’re just measuring the same machine on different clocks. We use the run-hour multiplier as the gut check before any replace recommendation. How to Find Out How Old Your AC Actually Is Before you decide what to do about it, you need to know exactly how old “it” is. The answer is on the data plate of the outdoor condenser, a metal sticker usually on the side facing the wall. Bring a flashlight. Decoding the Serial Number on Carrier, Trane, Lennox, Goodman, Rheem Each manufacturer encodes the build date differently. Here’s the cheat sheet: Brand Where to look How to decode Carrier / Bryant Outdoor unit data plate First 4 digits = WWYY (week + year). 3217E12345 = week 32 of 2017 Trane / American Standard Outdoor serial label