What does CONT. FAULT mean on a Quincy QSI compressor?
Short answer: Contactor state fault. If your Quincy QSI series (QSI standard controls) is showing CONT. FAULT, the controller has logged a specific, documented condition. This page covers what it means, what causes it, what you can safely fix yourself, and when — and why — it takes a technician.
What exactly is the machine telling you?
The main contactor failed to match the state the controller commanded (running or stopped), so the controller tripped a fault.
Which machines show this?
Quincy QSI industrial rotary screw compressors with the standard QSI control panel — larger plant-air packages, some fitted with Quincy's integrated refrigerated dryer, whose faults (DRYER CONT., DRYER D.P.) appear on the same display without stopping the compressor. The QSI panel reports faults as short text messages — OVERLOAD, HIGH TEMP, SUMP HAT, TEMP FAULT — rather than numeric codes, so search the exact wording on your display. "Sump" in these messages means the fluid separator vessel, and "fluid" is Quincy's term for the compressor lubricant. Faults clear from the panel after the cause is corrected; the manual keeps the electrical enclosure strictly off-limits to unqualified hands.
What causes it?
- The main contactor didn't open or close when the controller commanded it
- Welded or failed contactor contacts, or a control-circuit fault driving it
Can you fix it yourself?
No — do not keep resetting and restarting. Note whether it tripped on start or stop and make the call; a contactor that ignores commands is a genuine electrical failure.
Step by step — what to try, in order:
- Do not repeatedly reset and restart the machine
- Note the message and whether the compressor was starting or stopping when it tripped
When do you need a technician — and why?
The contactor switches the full motor voltage; a contactor stuck closed can't even be stopped normally. This is high-voltage cabinet work, flagged no-DIY by the manual.
If it does come to a service call and you're in Nashville, TN or Birmingham, AL, we maintain independently compiled lists of local companies that service industrial air compressors — real businesses with verified contact information, none of whom paid to be listed.
Related questions
What does CONT. FAULT mean on a Quincy QSI series (QSI standard controls)?
Contactor state fault. The main contactor failed to match the state the controller commanded (running or stopped), so the controller tripped a fault.
Can I fix CONT. FAULT on a Quincy QSI series (QSI standard controls) myself?
No — do not keep resetting and restarting. Note whether it tripped on start or stop and make the call; a contactor that ignores commands is a genuine electrical failure.
When does CONT. FAULT on a Quincy QSI series (QSI standard controls) need a technician?
The contactor switches the full motor voltage; a contactor stuck closed can't even be stopped normally. This is high-voltage cabinet work, flagged no-DIY by the manual. Call a qualified technician immediately — a contactor that does not open or close on command is a high-voltage electrical failure.
Verified against service documentation: Quincy QSI series (QSI standard controls) documentation for CONT. FAULT (manualslib.com)