Air Filters
Evaporator and Condenser Coils
Fan Blades and Motors
Condensate Drain Lines
Ductwork
Grilles and Registers
Refrigerant Lines
Outdoor & Indoor Units
Thermostat
Refrigerant Leaks
Compressor Issues
Fan Motor Problems
Thermostat Malfunctions
Blower Motor Issues
Capacitor Failures
Electrical Problems
Condenser Coil Problems
Evaporator Coil Issues
Expansion Valve Problems
Ductwork Issues
Heat Exchanger Problems
Water Leaks
Control Board Issues
Airflow Problems
Air conditioning repair that starts with a measurement, not a guess
Air conditioning repair on a house starts at the indoor coil with two thermometers, because the temperature split across that coil says whether the system is still moving heat before anyone decides which part to blame. We diagnose and repair central air conditioning, heat pumps in cooling and ductless systems for homes across Long Island.
- Low. The coil is barely taking heat out of the air passing it.
- Expected. Judged against how humid the house is that day, not off one figure.
- High. The air is being cooled hard because there is too little of it.
No cooling right now, in real heat or after hours? The line is answered every day of the year and a technician is typically on site within 90 minutes.
631-710-6257Before you call
Four things you can safely check yourself
Some of the calls that come in during the first hot week are not repairs. These four take a few minutes and stay clear of the sealed system and the line-voltage side.
01
The thermostat
Set to cool, target below what the room reads, batteries good. The setting that fools most people is the fan: left on On instead of Auto, the blower runs between cooling cycles and pushes room-temperature air out of the registers. That gets reported as an air conditioner blowing warm, and it is a switch.
02
The filter
Pull it and hold it up to a light. If you cannot see light through it, it is starving the system, and a filter is the most common cause of a call that ends in ice. Check it sits flat and faces the way the arrow says: one that has collapsed in its rack lets air bypass it and load the coil instead.
03
The power
There are usually two circuits, one for the outdoor unit and one for the furnace or air handler, plus a switch that looks like a light switch beside the indoor unit and gets flipped by whoever was last in the basement. Check the switch, then the panel, and reset a tripped breaker once.
04
The outdoor unit
It has to breathe. Clear grass clippings, leaves and cottonwood off the sides, cut back anything growing into it, and take off a cover left on over winter.
The diagnosis
What a technician measures, and why the gauges come last
Every reading taken on a cooling system is shaped by the air arriving at the coil. Measure the sealed system first and you end up describing the filter. The work runs from the air side inward, and the first real number is free.
The number that starts it
The temperature split
One thermometer in the return air entering the indoor coil, one in the supply air leaving it, both read once the system has run long enough to settle. The difference is the split, and it is the plainest statement of whether the coil is still doing work. It is taken before a hose touches the unit, and again at the end to prove the repair.
It is judged against the moisture in the house that day. On a humid afternoon much of the coil's work goes into pulling water out of the air rather than dropping its temperature, so a healthy system reads a smaller split in August than in May.
Two ways it goes wrong
A low split and a high split point opposite ways
A low split means the air leaves almost as warm as it arrived. The coil is not absorbing much, which puts the fault on the refrigerant side or on the coil surface: a charge leaked down, a restriction feeding it, a compressor no longer pumping as it did, or a fin pack loaded with dirt on the side nobody sees.
A high split is the opposite. The air leaving is very cold and there is not enough of it: a loaded filter, a blocked or undersized return, a duct crushed in an attic, a blower wheel packed with dust, a motor running slow. It is the reading that comes just before a coil freezes.
The call, and what both units do with it
Whether the thermostat is calling, whether the blower starts, and what the outdoor unit does in the first seconds. A click and a hum with no rotation says something different from a fan that spins up cleanly.
Filter, returns and the coil faces
The filter and its rack, the return grilles and whatever is stacked over them, the entering face of the indoor coil, and the outdoor unit's clearance.
The split, taken properly
With air moving as it should, the split is measured and the humidity noted with it. This is the fork in the road, and it happens before any refrigerant is disturbed.
The electrical side of the condenser
Voltage at the contactor on a call, capacitance against the rating printed on the can, and the current the compressor and fan draw. A large share of residential repairs are decided here, with no gauges involved.
Gauges, and a leak search if the charge is down
Only now, and only if the evidence points inside. Every connection to a service port costs a little refrigerant and puts a Schrader core at risk, so a gauge set answers a question the first four steps raised.
Cooling fault decision tree
Start from what you can see, and follow it to the fault group
Pick what the system is doing, answer the follow-up, and you get the fault group behind it and what a technician looks at first. Two houses with the same complaint fail for different reasons, so this narrows the call rather than settling it.
1. What is happening
Choose the one that fits best.
2. One more question
This is the answer that splits the causes apart.
What is the indoor unit doing?
What is the outdoor unit doing while the thermostat calls?
Is this new, or has the house always been like this?
Is this the first time it has iced up?
Where is the water showing up?
When does the noise happen?
How often does the breaker go?
If two answers both fit, take the one you have seen most recently.
3. What it points at
The fault group, and the first thing a technician looks at.
The indoor unit has no power, or is being held off
A tripped breaker, the service switch off, a blown low-voltage fuse, a failed transformer, or a float switch holding the circuit open on purpose.
Airflow, at the blower or in front of it
A filter loaded solid, blocked returns, a blower wheel packed with dust, a motor running slow, or a coil already iced.
The starting components on the condenser
A contactor not pulling in, a capacitor too weak to turn the compressor on a hot day, or a compressor opening its own overload. All three look identical from the ground.
Capacity lost in a machine that sounds healthy
A charge down from a leak, a condenser that cannot shed its heat, a dirty indoor coil, a restriction, or a compressor no longer pumping to specification.
Something in the machine has changed
Capacity lost somewhere: charge, coil condition, airflow, or a compressor past its best. Roughly when it started narrows it further.
Load against capacity, rather than a fault
A system asked for more than it was sized to give. Ducts, returns and insulation carry as much of that as the equipment does.
Thaw it before anything else
Too little air over the coil, or too little refrigerant in it. The ice hides every reading that would tell them apart, so switch the cooling off and leave the fan running.
A cause that was never found
Icing that returns within days means the restriction or the leak behind it was never found. Thawing and restarting buys an afternoon and sends liquid refrigerant back at the compressor.
The condensate drain
A drain line blocked with biofilm, a pan rusted through, a line pitched back toward the unit, or a secondary pan that has filled. Turn the system off so it stops making water.
A float switch doing its job
Often not a cooling fault at all. The float switch in the pan is cutting the system off as water rises and resetting as it drains.
A start that is not completing
The click is the contactor closing, the hum is the compressor trying to turn, the silence is its overload opening. A weak run capacitor is the usual reason.
Mechanical, and worth catching early
A squeal or growl that tracks fan speed is a bearing. A rattle is a loose panel, a blade clipping its grille, or debris in the coil basket. A bang from the ducts at shutdown is sheet metal flexing.
Worth logging, not chasing
A single trip during a storm or on the hottest afternoon may be the supply rather than the equipment. Note the day and the weather. What matters is whether it becomes a pattern.
Stop resetting it
Usually a compressor winding gone to ground, a seized motor, a capacitor failed shorted, or a wire chafed against the cabinet.
Rather talk it through? 631-710-6257
Ductless systems reach several of these answers by a different route, because the indoor hardware is a wall head rather than a coil in a duct. That work sits with ductless mini split maintenance.
Refrigerant
Leaks: where they start, how they are found, what a repair means
A sealed system does not use refrigerant up. If the charge is down it went out through a hole, and finding that hole is the repair. From indoors a leak looks like cooling that fades over weeks, ice on the thick copper line, and an oily, dirt-collecting film at a fitting outside.
Where they start
The evaporator coil
The indoor coil lives in warm, wet air and is built from thin aluminum and copper. Moisture with the organic vapors that collect in a closed-up house forms weak acids on that metal and eats pinholes through it, too small to see and too widespread to patch. It reads as a charge fading across a season.
Where they start
The line set
The two copper lines between the outdoor unit and the coil are soft, and they were run through whatever path the house allowed. They chafe where they pass a joist or a strap, crack at a bend pulled too tight on install day, and take hits from shovels and mowers near the outdoor unit.
Where they start
Valves and Schrader cores
The service ports that gauges connect to are sealed by small rubber-tipped cores, and cores harden, seat badly and seep. Valve stems and caps are the same story. The cheapest leak here to correct, and the easiest to walk past.
Where they start
Brazed joints
Every place two pipes were joined is a candidate. A joint brazed without dry nitrogen flowing through the pipe grows oxide scale inside, which sheds into the system and can leave the joint porous. Vibration then cracks a joint where it is stiffest.
Where they start
The outdoor coil
Exposed fins and the hairpin bends at the ends of the tubes corrode from the outside in, faster in salt-laden air. Add a side yard, where a string trimmer or a pressure washer held too close flattens fins and eventually opens a tube. Flattened fins on their own are an airflow problem and can often be combed straight; a tube opened behind them is a leak, and on a coil that far gone the repair is usually the coil rather than the spot.
How a leak is found
A leak old enough to matter signs its own name in oil, so that is where the search starts. From there a technician works the circuit with an electronic detector, low and slow, because the refrigerant pools below a leak rather than above it, and anything it flags is confirmed with bubble solution.
Two cases need another route. A system that has lost its charge completely has nothing left to detect, so it is pressurized with dry nitrogen and the circuit soaped and watched on a gauge over time. A very slow leak gets fluorescent dye added to the oil and a return trip with a lamp once it has circulated. Some leaks take two visits by their nature, and it is fairer to say so at the start than to guess at a part.
Why a top-up on its own is not a repair
Charge a leaking system and the house cools that afternoon. The leak carries on, the charge goes back out, and you buy the same fault again in worse weather. In between the compressor runs short of refrigerant, which means short of the oil that travels with it and of the cool suction vapor that carries heat away from its windings. Selling that as a repair, twice to the same customer, is what gives this trade a bad name.
The repair itself runs in order: recover the charge into a cylinder rather than venting it, repair the component, pressure test, pull a deep vacuum, then weigh the charge back in to the weight the manufacturer specifies. The vacuum is not a formality, because moisture left in a circuit combines with refrigerant and heat to form acids that attack the compressor from inside.
Ice
A frozen coil, and why switching it off is the right first move
An indoor coil runs cold enough to condense water out of the air. That is the job. When it drops below freezing, the water that should drain into the pan freezes onto the fins instead and blocks the gaps the air was passing through. Less air makes the coil colder still, which makes more ice, and within an hour or two the coil is a solid block.
It matters beyond the inconvenience. Refrigerant that does not finish boiling in the coil travels back down the suction line as liquid, and a compressor is built to pump vapor. Liquid arriving at it is what turns a filter nobody changed into a compressor failure, and it is why a frozen system should not be left running while you wait for an appointment.
What to do before we arrive
- Switch the cooling off and set the fan to On. Room air over the coil thaws it far faster than leaving everything off.
- Put towels down. All of that ice becomes water, and a pan already holding meltwater can overflow.
- Change the filter while it thaws, and open every return and supply register in the house.
- Do not chip, scrape or pry the ice. The tubing under it is thin, and a screwdriver turns a cheap repair into a refrigerant leak.
- Do not switch the cooling back on until it is fully clear, or you are an hour further from a diagnosis.
Fault families
Four more calls, and what each one is telling you
Each of these arrives on the phone as a description of a symptom. Each has a small group of causes behind it and one measurement that sorts them out.
01
It runs all day and never satisfies
What is worth a call is a change: it used to catch up and now it does not, or the air at the register is barely cooler than the room it is blowing into. The split separates the two cases. A healthy split and a house that still will not hold means the system is fighting load, which is a question about ducts, insulation and what the house has become since the equipment went in. A poor split means something measurable has been lost. Short cycling is the opposite complaint and a different list: a thermostat in the sun or above a lamp, or a safety opening and resetting itself.
02
The two parts that fail most on a condenser
The run capacitor is the part we replace more than any other. It stores and releases a charge to give the compressor and the outdoor fan the push they need to start and the phase shift that keeps them turning, and it does not fail cleanly. It weakens, and a weak capacitor turns a compressor in mild weather but fails against the pressures of a hot afternoon, which is why so many of these calls land on the first genuinely hot day. It is measured against the rating printed on the can, and it holds a dangerous charge after the power is off.
The contactor is the relay that puts line power onto the compressor and fan. Its contacts arc on every start, so they pit, and they either stop closing, which gives a hum and nothing else, or weld shut, which leaves the outdoor unit running whether anything is calling for it or not. Insects nesting under the armature are a genuine cause here and not a rare one.
03
A breaker that will not stay in
A breaker doing this is not a nuisance to work around. It is a protective device carrying real fault current every time it is closed on a fault, and each reset sends that current through the wiring, the breaker itself and whatever is failing at the far end. Reset it once, then leave it off and call, and never wedge one in or fit a larger one to quieten the problem. A technician measures insulation resistance and current draw before naming a part, because some of what sits behind that breaker is inexpensive and one possibility is not.
04
Water, and noise
Water almost always means condensate. The coil removes moisture from the air by design and drains it through a pan, a trap and a line that ends outside or at a house drain. That line spends its life wet and dark, biofilm grows in it, and a blockage backs the pan up. Under an attic air handler the same fault reaches you as a ceiling stain, which is why those units sit in a secondary pan with a float switch wired to shut the system down first.
With noise the useful information is timing, and the tree above sorts it. A bearing that squeals for a week is a motor; a bearing left to seize is a motor plus whatever it took with it.
Local conditions
What Long Island does to a condenser and a line set
Two things shape the repair work here more than anything else: the air the outdoor unit sits in, and the way cooling was added to houses that were not built with it.
Salt-laden air reaches a long way inland from both shores, and an outdoor coil is a stack of thin aluminum fins pressed onto copper tubes. Two different metals in constant contact, kept damp and salted, corrode faster together than either would alone. A coil corroding from the outside in eventually opens at a tube or a hairpin bend, and that is a leak in the part of the circuit hardest to patch and often replaced as an assembly.
Central air arrived in most Suffolk County houses years after they were built, so the copper was run wherever there was a path: through a crawlspace, down a chase in an exterior wall, along the outside of the house, under a deck added later. A leak in an accessible run is a straightforward repair. A leak in a section buried under a walkway or sealed inside a finished wall is a different job, and the honest answer is sometimes a re-route rather than a patch. The black foam insulating that line fails early here too, split and brittle from sun and salt, and a bare line sweats and drips wherever it runs.
Then the side yards. A great many condensers here were set in the gap between two houses because that was the space available, and a unit throwing heat upward into a narrow slot can draw some of that same warm air back through the coil. Add a fence or a deck built a decade after the unit went in, and a machine that worked for years starts struggling with nothing wrong inside it. Clearance gets checked on every repair visit, because a repair made in bad conditions is a repair that comes back.
Where the outdoor unit sits decides what fails on it. Roof, side yard or open lawn each give a coil a different life.
Catching it before July
Coil condition, capacitor readings, clearance and the drain are all things a spring visit finds while there is still time to act on them. That scope belongs to air conditioning maintenance.
The decision
When a repair stops being the right answer
This is a judgment, and it comes out of the diagnosis rather than off the data plate. What moves it is what the diagnosis answers that a quote never can.
The first question is where the fault sits. A leak at a valve core, a line set section that can be reached, a fan motor, a control board: repairs, without qualification. A leak inside the evaporator coil or in a corroded condenser coil is a component replacement, and replacing one half of a matched pair raises a fair question about the other half.
The second is what the fault did on its way out. A compressor that fails electrically and a compressor that burns out are two different repairs, because a burnout puts acid and debris through the whole circuit, and the line set and coil either get cleaned up properly or they take the replacement compressor down with them. That is the point where doing the job right starts to approach the cost of the machine.
The third is the pattern. One failure is a repair. Three unrelated failures inside two seasons is a system telling you something, and so is a charge lost twice from a coil that cannot be repaired in place. When replacement is the honest answer you get both figures before anything is ordered, and the sizing and equipment conversation moves to air conditioning installation where it belongs.
Questions
Air conditioning repair questions we get asked most
My system is frozen solid. What should I do right now?
Switch the cooling off at the thermostat and set the fan to On, so house air moves over the coil and thaws it. Put towels down, because the ice becomes water and the pan may already be full. Change the filter and open every register while it clears. Do not chip at the ice: the tubing under it punctures easily and that turns a cheap fault into a refrigerant leak. Leave the cooling off until someone has looked at it, because a coil that froze once will freeze again until the cause is found.
Can I just add refrigerant myself?
No. Refrigerant handling requires EPA Section 608 certification under the Clean Air Act, and a system low on charge has a leak, so adding more without finding it wastes the refrigerant and your money. Sealant additives sold as a fix are worse than nothing, because they can set in the metering device and contaminate the equipment used to recover the charge later. Find the leak, repair it, then weigh the charge in.
The breaker for my outdoor unit keeps tripping. Can I keep resetting it?
Reset it once. If it trips again, leave it off and call. A breaker that opens repeatedly is carrying fault current every time you close it, and behind it there is usually a compressor winding gone to ground, a seized motor, a shorted capacitor or a chafed wire. Never fit a larger breaker to stop it happening. The measurements that identify which of those it is take a technician a few minutes.
What should I have ready when I call?
Where the indoor unit is: basement, attic, closet or a wall head. What the outdoor unit does when the thermostat calls, in your own words, since a hum and a click says something different from a fan running normally. Whether anything is iced, whether there is water anywhere, and roughly when the filter was last changed. A photograph of the label on the outdoor unit beats a description, because the brand, model and refrigerant on it decide what goes on the truck.
Talk to a technician
Tell us what the system is doing
Describe the symptom and you will get a straight answer about what it most likely is before anyone is dispatched. If the house is hot right now, call. Emergency cover runs every day of the year with a typical on-site response inside 90 minutes, and quotes and planned work run Monday to Friday, 8am to 5pm.