AC compressor repair & replacement
Told your compressor is dead?It is often something cheaper.
A compressor that hums, trips the breaker or refuses to start looks identical whether it has genuinely failed or whether a failed capacitor is stopping it. One of those costs a few hundred dollars. Make sure somebody actually checked.
Six things that look exactly like a dead compressor
Every one of these produces the same symptoms — humming, tripping, not starting, or running without cooling. Five of them are far cheaper than a compressor, and all of them are measurable in minutes.
A failed run capacitor
The most common cause of a compressor that hums but will not start, and by far the cheapest to fix. It is a single reading in microfarads against the rated value on the can. If nobody put a meter on your capacitor, the compressor has not been ruled in.
A pitted contactor
Burned contacts drop voltage before it ever reaches the compressor, which then cannot draw enough current to start. Measured as voltage drop across the closed contacts. An inexpensive part that produces very convincing symptoms.
A tripped internal overload
Compressors have a thermal protector that opens when they get too hot and resets once they cool. A compressor that seems dead in the afternoon and runs in the evening has not failed — something is making it overheat, and that something is the actual problem.
Supply voltage or wiring faults
Low incoming voltage, a loose lug, a failed disconnect or a damaged whip will all stop a perfectly healthy compressor. Checked with a meter at the unit while it attempts to start, not assumed from the breaker panel.
A seized condenser fan
If the outdoor fan is not turning, head pressure climbs until the compressor shuts down on its overload. The compressor is fine. The fan motor is the failure, and it is a fraction of the cost.
Genuine compressor failure
Confirmed by measuring winding resistance between the common, start and run terminals, testing for a winding shorted to ground, and reading amp draw at start. An open winding, a grounded winding or locked-rotor current all confirm it properly — and none of that is a guess.
Ask the company that quoted you one question: what did the compressor's winding resistance and capacitor microfarad readings actually measure? A technician who tested it will have numbers. A technician who assumed it will change the subject.
Why compressors actually fail
This matters more than it sounds. Compressors rarely die of old age — something usually kills them, and if that something is not found, it will kill the replacement too.
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Running low on refrigerant
Refrigerant cools the compressor as well as your house. A system losing charge through a leak runs the compressor hot and starved for weeks or months before it finally quits. Replacing it without finding the leak guarantees a repeat.
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A condenser coil packed with valley dust
A dirty coil cannot reject heat, so head pressure and discharge temperature climb. In Fresno, with agricultural particulate and 100-plus days above ninety, this is one of the most common root causes we see.
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Restricted airflow indoors
A blocked filter, collapsed duct or dirty evaporator coil starves the system and can send liquid refrigerant back to the compressor. Compressors pump gas, not liquid, and liquid returning is mechanically destructive.
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A weak capacitor left in place
A capacitor drifting out of tolerance makes the compressor strain on every start. It works, right up until it does not, and the damage accumulates for a long time first. This is precisely what an annual capacitor reading prevents.
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Short cycling from an oversized system
Compressors wear on starts far more than on run time. A system sized too large for the house starts and stops constantly, and racks up that wear years faster than a correctly sized one. More on sizing.
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Contamination left from a previous failure
If a compressor has burned out before and the system was not properly cleaned up afterwards, acid and debris remain in the lines waiting to attack the next one.
Any honest compressor quote should tell you what caused the failure. If nobody can say why it died, nobody has established that the replacement will not follow it.
The expensive shortcut
If it burned out, the system needs cleaning up
When a compressor fails electrically, the motor windings burn inside a sealed system full of refrigerant and oil. That produces acid and carbon which do not leave when the compressor does — they stay in the line set, the evaporator coil and the metering device.
Fit a new compressor into that without cleaning it out and the acid attacks the new windings. It might last a year. Sometimes less. The homeowner is then told they have terrible luck with compressors.
Skipping the cleanup saves a couple of hours and a few parts. It is invisible on the invoice and it is the most common reason a replacement compressor fails early.
What a burnout cleanup requires
- An oil acid test to establish whether the system is contaminated at all
- A suction line filter drier fitted to capture acid and debris
- Line set flushed or replaced where contamination is significant
- The metering device inspected, and replaced if debris has reached it
- A follow-up drier change after the system has run, on a severe burnout
Before you agree to anything
Check whether the compressor is still covered
Manufacturer parts warranties commonly run around ten years on registered residential equipment, and compressors are covered — sometimes with a longer term than other parts. If yours is inside that window, the compressor itself can arrive at no cost and you are paying labor, refrigerant and cleanup only.
It takes a model and serial number and a few minutes to check, and it changes the entire decision. It is also skipped constantly, particularly when the next slide is a replacement proposal. Text a photo of your data plate to (559) 520-4240 and we will look it up, whether or not we installed the system.
Compressor, or the whole system?
This is a genuine fork, not a formality. Both answers are right in different situations, and the difference is usually four things: warranty, refrigerant, age and what else the readings show.
Replace the compressor
- It is still under manufacturer warranty, so you pay labor only
- The system runs R-410A or newer
- It is under roughly ten years old and the coil is sound
- The root cause has been found and can be corrected
- The ductwork and sizing are already sound
- You are selling or moving within a couple of years
Replace the system
- The compressor is out of warranty and the system is past a decade old
- It runs R-22, where recharging alone is a substantial cost
- A severe burnout has contaminated the coil and line set as well
- The evaporator coil is also leaking or near end of life
- The repair approaches half of a complete, permitted replacement
- It was sized wrong originally and short cycling caused the failure
One more honest option: on a compressor that is struggling to start but still running, a hard start kit can sometimes buy a season while you plan properly. It is not a fix and we will say so — but it beats making a five-figure decision in a panic in July. See the full framework.
What a proper compressor replacement involves
A compressor is not a bolt-in part. The steps around it are what determine whether the new one lasts a decade or a season.
- Root cause identified and corrected first
- Refrigerant recovered legally rather than vented
- Oil acid test on a suspected burnout
- Correct replacement compressor, matched to the system
- New liquid line filter drier, every time
- Suction line drier where contamination is present
- New capacitor and contactor rather than reusing the old ones
- Nitrogen purge while brazing to prevent internal scale
- Pressure test before evacuation
- Deep vacuum verified with a micron gauge and a decay test
- Charge weighed in, then confirmed by superheat and subcooling
- Condenser coil cleaned and amp draw verified under load
If a compressor quote does not mention a filter drier, a nitrogen purge and a deep vacuum, ask what is being done instead. Those three steps are most of the difference between a repair and a delay.
What it costs
Warranty status is the biggest single variable
Compressor replacement in the Fresno area typically runs in the range below when the part is not covered. Where the compressor is still within the manufacturer's warranty, you pay labor, refrigerant and any cleanup only, which is a very different number.
Refrigerant type moves it further. An R-22 system needs an increasingly scarce refrigerant to recharge, which is a large part of why compressor failure on R-22 equipment so often points toward replacement instead.
Holding a quote right now
This is the decision most worth checking twice
We will test the compressor windings and capacitor properly, establish what actually caused the failure, check the warranty status against your model and serial, and tell you plainly whether the recommendation holds up. Sometimes the other company was right and we say so. Free, no obligation, and you keep the readings.
Compressor questions
Can an AC compressor be repaired rather than replaced?
Not in residential systems. A compressor is a sealed unit and is replaced rather than rebuilt. What can be repaired are the things that look like compressor failure — the capacitor, contactor, wiring, condenser fan motor or a tripped overload — which is exactly why proper testing matters before anyone commits to the expensive answer.
How much does compressor replacement cost in Fresno?
Typically $1,800 to $3,500 when the part is not covered by warranty, varying with system size, refrigerant type and whether a burnout cleanup is required. If the compressor is still within the manufacturer's parts warranty you pay labor, refrigerant and cleanup only.
Is it worth replacing a compressor on a 15-year-old system?
Usually not, though it depends on the specifics. At that age the compressor is generally out of warranty, the coil is approaching the end of its life, and the repair often approaches half the cost of a properly installed replacement. If the system also runs R-22, replacement is almost always the better use of the money.
My AC hums but will not start. Is the compressor dead?
Often it is not. Humming without starting is the classic symptom of a failed run capacitor, and it is also produced by a pitted contactor or low supply voltage. All three are inexpensive compared with a compressor and all three are measurable in minutes. Have the capacitor read in microfarads before accepting a compressor diagnosis.
How long should a compressor last?
Usually as long as the system itself, commonly 12 to 18 years, though Fresno run hours shorten that compared with milder climates. A compressor failing well before that almost always has an underlying cause — low refrigerant, a dirty condenser, restricted airflow or a weak capacitor — rather than simply being unlucky.
Will a new compressor come with a warranty?
The part typically carries a manufacturer warranty. Labor coverage is separate and comes from the contractor, not the manufacturer, which matters a great deal on a repair this labor-intensive. Ask for the labor term in writing. More on how coverage works.
What is a hard start kit, and would it help?
It is a capacitor and relay assembly that gives the compressor extra torque on start-up. On a compressor that is struggling but still running, it can sometimes buy time. It is not a repair and it will not save a failed compressor, but it can be a legitimate way to get through a season while you plan a replacement calmly rather than in a heat wave.
Get it tested properly before you decide
Windings and capacitor measured, root cause established, warranty checked, and both numbers put in front of you.
Prices shown are typical ranges for the Fresno area and are not quotes. Manufacturer warranty terms vary by brand, model and registration status. California Heating & AC Repair is operated by Craftline Renovations, Inc. · CSLB License #999179 · Licensed and insured.