Short answer: a capacitor is good when its reading sits close to the µF value printed on its label. Carrier’s split-system service manual says to replace one that’s more than 10% off. On 11 paid AC capacitor repairs in our records from April to October 2026, the capacitor was the whole fix only 3 times. The other 8 also needed a contactor, wiring, a fan motor or a fuse.
Testing one yourself isn’t safe, because it holds a charge after the power is off. Below is what the numbers mean when a technician reads them back to you, what those 11 calls looked like, and the checks the manufacturer says you can do first.
What we found on our 2026 AC capacitor calls
Between April and October 2026, our CRM has 11 paid AC repairs where the technician’s notes or the invoice say we replaced a capacitor. They were at 10 addresses; we were called to one Fremont address twice. Our HVAC jobs rarely have a brand filled in, so we searched the job descriptions, technician notes and invoices instead, and kept only jobs that name the air conditioner. Older records imported from our previous system are too thin to search this way, so this is April to October only. It’s a small local sample.
| What we found | Calls | What was reported | What it took |
|---|---|---|---|
| Failed capacitor, nothing else | 3 | AC not cooling or not working. On one, air came out of the vents but the outdoor unit never started | New capacitor |
| Capacitor and contactor | 5 | AC on but not cooling or blowing warm air (4). On the fifth, the AC’s blower fan never ran | New capacitor and contactor. Two also needed rewiring, one needed refrigerant added, and one needed the condenser coil cleaned and a new filter |
| Capacitor and a wire terminal | 1 | AC not working | New capacitor and a new terminal on a wire connection |
| Capacitor and outdoor fan motor | 1 | Outdoor fan not running | New fan motor and capacitor |
| Capacitor and a control board fuse | 1 | Outdoor fan running, air inside warm | New capacitor and a new fuse on the control board |
Where those 11 were:
| City | Calls | What we found |
|---|---|---|
| Fremont | 4 | Capacitor and contactor 3, capacitor and wire terminal 1 |
| San Ramon | 2 | Capacitor only 2 |
| Hayward | 2 | Capacitor and contactor 2 |
| Dublin | 1 | Capacitor and fan motor |
| Pleasanton | 1 | Capacitor only |
| Union City | 1 | Capacitor and control board fuse |
A new capacitor fixed the AC by itself on 3 of 11 calls. On the other 8, we also replaced a contactor, a fan motor or a fuse, repaired wiring, added refrigerant or cleaned a dirty coil.
How to tell the causes apart
Air blows from the vents, but the outdoor unit is silent. The compressor and outdoor fan aren’t starting. Goodman’s “No Cool” troubleshooting chart walks a technician through power to the unit, the 24-volt signal from the thermostat, the contactor, the wiring and the run capacitor. On our one call like this, it was the capacitor alone.
The outdoor fan runs, but the air inside is warm. That can mean the compressor isn’t starting. For a compressor that won’t start (the Locked Rotor alert), Goodman’s manual lists a failed run capacitor first, then low line voltage, excessive liquid refrigerant in the compressor and seized bearings. Our call like this needed a capacitor and a fuse on the control board.
Air blows, but it’s warm. That’s how 4 of our 5 contactor calls were reported. Low refrigerant can look the same, and one of those calls needed refrigerant along with the new parts.
A hum, and the fan doesn’t spin. A weak capacitor can leave a motor without the starting torque it needs. It isn’t always the capacitor alone: on one of our calls the outdoor fan wasn’t running, and it needed a new fan motor as well as a capacitor. Keep hands and sticks out of the grille. A powered fan can start on its own.
A variable-speed (ECM) motor won’t run. Carrier’s manual notes that ECM motors don’t use capacitors, so a capacitor isn’t the answer there.
What Goodman’s manual says you can check first
Goodman’s condensing unit installation and service reference (IO-258) has a “Before calling your servicer” list for homeowners:
- Check the thermostat and make sure it’s set properly.
- Wait 15 minutes. Some devices in the outdoor unit or in programmable thermostats hold the compressor off for a while and then reset on their own. Goodman adds that some power companies install devices that shut air conditioners off for several minutes on hot days.
- Check your home’s breaker panel or fuse box for a tripped breaker or a failed fuse. Goodman says to reset the breaker or replace the fuse with one of the same amperage, and to call a qualified servicer if it opens again within thirty days.
- Check the disconnect switch near the indoor furnace or blower and make sure it’s closed.
- Check the outdoor unit for anything covering its sides or top and remove what can be safely removed. If the unit is covered with dirt or debris, have a servicer clean it.
- Check the indoor vents and returns for rugs, curtains or furniture blocking them.
- Check the filter. Clean or replace it if it’s dirty. The same manual says to check it at least once a month.
- Listen to the outdoor unit. If you hear an unusual noise, call a servicer.
Stop there. Don’t open the disconnect box or the access panel on the outdoor unit, and don’t pull or replace fuses there. Goodman’s manual also warns that resetting a breaker over and over without fixing the cause risks severe equipment damage.
What the numbers mean
A capacitor is rated in microfarads, written µF or MFD. Some outdoor units use one dual capacitor for both motors, and its label shows two numbers. On the Carrier we repaired in Fremont it was 70/5 µF: the 70 side runs the compressor and the 5 side the outdoor fan. Goodman’s manual calls the compressor terminal HERM and the common terminal C.
- Close to the label is good. Goodman’s service manual says a reading near the printed value means the capacitor is good, and notes the reading may be less than the printed value.
- More than 10% off means replace. That’s the rule in Carrier’s split-system service manual. On a 70 µF side, that’s below about 63 or above about 77. On a 5 µF side, outside 4.5 to 5.5.
- Far below the label, or nothing at all, means dead. Goodman’s words: “significantly lower capacitance or none at all,” and the capacitor must be replaced.
Technicians can also test a capacitor under load, with the system running and the unit’s panel open. Both manuals give a formula from the current through the capacitor and the voltage across it, and Goodman says that gives a more accurate picture of how it performs. That’s a live-voltage test inside the unit, so it’s strictly a technician’s job.
On one of our Fremont calls the capacitor had about 20% of its rated capacity left. That same unit also had a condenser coil so dirty it wasn’t moving heat. We replaced the capacitor and contactor, cleaned the coil and changed the filter.
Why a technician should handle this
Capacitors hold a charge after the power is off. Goodman tells technicians to discharge one through a 200 to 300 ohm resistor before handling it. Carrier says to short across the terminals with a 15,000-ohm, 2-watt resistor, to check capacitors only with the power off, and warns that a defective capacitor may explode when power is applied.
The other reason is what our calls showed. On 8 of 11, the capacitor wasn’t the only thing that needed fixing. You get the cause and a written estimate to approve before any work starts.
What it costs
- Diagnostic visit: $99, credited toward the repair if you go ahead with us.
- A typical minor HVAC repair, such as a capacitor or contactor: $250 to $650 for parts and labor. That’s the usual range for this kind of repair, not a quote for every system.
For more on the price, see what an AC capacitor replacement costs. If the capacitor checks out and the system still short cycles, our guide to Goodman AC short cycling covers the other usual causes.
When to call
Call (925) 999-4095 to schedule a visit.
Call when the outdoor unit won’t start after the checks above, when it hums without spinning, or when it runs and the air stays warm. Turn cooling off at the thermostat while you wait. Tell us the brand and model if you can see the label, and what the outdoor unit is doing.
We do AC repair across the East Bay and Tri-Valley. These 11 calls were in Fremont, San Ramon, Hayward, Dublin, Pleasanton and Union City. We work on Goodman and Carrier systems and other brands.
The diagnostic visit is $99, credited toward the repair. Call (925) 999-4095 or request a visit. We’re open 7 AM to 7 PM, 7 days a week.
Related service example
Key takeaways
- A capacitor is rated in microfarads (µF). Carrier's split-system service manual says to replace one that reads more than 10% away from the value stated on it. On a 70/5 µF dual capacitor, that means about 63 to 77 on the compressor side and 4.5 to 5.5 on the fan side.
- On 11 paid AC repairs in our records from April to October 2026 where we replaced a capacitor, it was the only fix on 3. Five also needed a new contactor and 3 needed rewiring or a new wire terminal.
- Capacitors hold a charge after the power is off. Goodman and Carrier both tell technicians to discharge one through a resistor before touching it, and Carrier warns a defective capacitor may explode when power is applied. Testing one is a technician's job.
- Before you call, Goodman's homeowner list says to check the thermostat, wait 15 minutes, check your breaker panel or fuse box and the indoor disconnect, clear anything blocking the outdoor unit or the vents, and check the filter.
Related questions
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Need help with your system? Call (925) 999-4095 or book a visit. Repair diagnostics are $99, credited toward the repair. Installation assessments are free.
Further reading
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