MULETECH PRO
Nothing Outworks the Mule
Is Your Capacitor Bad?
A capacitor helps a motor start and keep running smoothly. Over time it wears out and can't hold its charge anymore. Answer a few quick questions below and we'll tell you if yours needs replacing.
⚠ Be safe before you touch anything
- Turn off the power at the breaker box first.
- Touch an insulated screwdriver across the capacitor's terminals to drain any leftover electricity.
- Now it's safe to test.
Not comfortable doing this yourself? Call a licensed HVAC technician instead — that's always the safe choice.
1 What kind of capacitor do you have?
Look at the label. Does it show one number or two numbers?
Dual Run
AC or furnace compressor/fan capacitor. Label shows 2 numbers, like 35/5.
Single Run
Blower motor capacitor. Label shows just 1 number, like 7.5.
2 What size is your capacitor?
It usually shows two numbers, like "35/5". Pick your size below, or choose "Different size" if yours isn't listed.
35 / 5
40 / 5
45 / 5
Different size
Don't see a percent on the label? ± 6% is the most common — it's fine to leave it as is.
3 Enter your meter readings
With your multimeter set to test capacitance (µF), touch one probe to the C (Common) terminal and the other probe to each of these two terminals:
Common → HERM
This checks against the bigger number on your label (the 35 in 35/5).
Common → FAN
This checks against the smaller number on your label (the 5 in 35/5).
—
Bigger number test (Common → HERM)
Your reading: —
Smaller number test (Common → FAN)
Your reading: —