Why did my Quincy QSI compressor shut down on OVERLOAD?
Short answer: Main motor overload tripped. If your Quincy QSI series (QSI standard controls) is showing OVERLOAD, 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 drive motor's overload protection has tripped, shutting the compressor down to protect the motor from overheating damage.
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?
- Main drive motor ran hot enough to trip its overload protection
- Hot, badly ventilated compressor room
- Blocked cooling-air intakes around the package
- An electrical or mechanical problem if it trips a second time
Can you fix it yourself?
Give the motor 15-30 minutes to cool, fix ventilation and blocked intakes, and reset once. Two trips in a row means stop — that's a diagnosis job, not a reset job.
Step by step — what to try, in order:
- Let the motor cool for at least 15-30 minutes before any restart attempt
- Check that the compressor room is well ventilated and not excessively hot
- Make sure cooling air intakes around the package are not blocked
- Reset the fault and restart once; if it trips again, stop and call for service
When do you need a technician — and why?
The overload relay and motor wiring live in the high-voltage enclosure; the manual explicitly warns against opening it or adjusting the relay yourself.
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 OVERLOAD mean on a Quincy QSI series (QSI standard controls)?
Main motor overload tripped. The main drive motor's overload protection has tripped, shutting the compressor down to protect the motor from overheating damage.
Can I fix OVERLOAD on a Quincy QSI series (QSI standard controls) myself?
Give the motor 15-30 minutes to cool, fix ventilation and blocked intakes, and reset once. Two trips in a row means stop — that's a diagnosis job, not a reset job.
When does OVERLOAD on a Quincy QSI series (QSI standard controls) need a technician?
The overload relay and motor wiring live in the high-voltage enclosure; the manual explicitly warns against opening it or adjusting the relay yourself. Call a technician if the overload trips a second time — repeated trips point to an electrical or mechanical problem that requires qualified diagnosis.
Verified against service documentation: Quincy QSI series (QSI standard controls) documentation for OVERLOAD (manualslib.com)