Question 1

What capacitor tolerance is considered acceptable?

Accepted Answer

The industry standard is ±6% of the labeled microfarad (μF) rating. A 45μF capacitor reading between 42.3μF and 47.7μF passes. Below 42.3μF means the capacitor is weak and should be replaced even if the unit still starts — it will fail soon and may cause a hard-start condition damaging the compressor.

Question 2

How do I safely discharge a run capacitor before testing?

Accepted Answer

Always disconnect power at the disconnect AND verify with a meter on the L1-L2 terminals before touching capacitor terminals. Discharge with a 20,000-ohm 2W resistor across the terminals for at least 5 seconds. Do NOT short with a screwdriver — that can pit the terminals and cause arc burns.

Question 3

What does a swollen or domed capacitor mean?

Accepted Answer

A bulged top or sides means the dielectric has failed and the case has pressurized. Replace immediately — do not test. A swollen capacitor can rupture and spray dielectric oil. Note this as the failure cause on your invoice; it usually indicates the unit ran in an overheating condition (locked rotor, low voltage, or running past rated amps).

Question 4

Can I replace a dual-run capacitor with two singles?

Accepted Answer

Yes — wire a single fan capacitor (typically 5μF) and a single compressor capacitor (typically 35-45μF) in place of the dual, with the common terminals tied together to a single C lead. Match the original microfarad and voltage ratings exactly. Most rooftops use this approach with a stacked-single mount.

Question 5

What is the difference between a run and start capacitor?

Accepted Answer

Run capacitors stay energized continuously while the motor runs — they are AC-rated, oil-filled, and have a long life. Start capacitors only energize during start (cycled by a potential relay or PTCR), are electrolytic, and have much higher μF ratings. NEVER substitute one for the other — start capacitors will explode if left energized continuously.

Capacitor Tolerance Check

Inputs

⚠️ Safety reminder

Capacitor Tolerance Check

Inputs

⚠️ Safety reminder

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