What does SUMP HAT mean on a Quincy QSI compressor?
Short answer: Sump high air temperature (snap disk). If your Quincy QSI series (QSI standard controls) is showing SUMP HAT, 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 snap-disk probe detected an over-temperature condition inside the sump (fluid separator vessel) and shut the compressor down.
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?
- Restricted cooling airflow around the package
- Fluid cooler exterior fouled with dirt
- Fluid level low in the sump
- Internal cooling or scavenge line problems when the trip returns
Can you fix it yourself?
Sometimes — cool the machine fully, clear the airflow, clean the cooler, verify fluid level, and try one monitored restart. A repeat sump over-temperature is teardown territory.
Step by step — what to try, in order:
- Let the compressor cool completely before doing anything else
- Check for restricted cooling airflow around the package and correct it
- With the unit off and cooled, clean the exterior of the fluid cooler
- After cooldown and full depressurization, verify the fluid level
- Reset and restart once; monitor the temperature reading
When do you need a technician — and why?
The sump is the pressurized fluid separator vessel; chasing scavenge-line and internal cooling problems means opening it, which requires full depressurization and a technician.
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 SUMP HAT mean on a Quincy QSI series (QSI standard controls)?
Sump high air temperature (snap disk). The snap-disk probe detected an over-temperature condition inside the sump (fluid separator vessel) and shut the compressor down.
Can I fix SUMP HAT on a Quincy QSI series (QSI standard controls) myself?
Sometimes — cool the machine fully, clear the airflow, clean the cooler, verify fluid level, and try one monitored restart. A repeat sump over-temperature is teardown territory.
When does SUMP HAT on a Quincy QSI series (QSI standard controls) need a technician?
The sump is the pressurized fluid separator vessel; chasing scavenge-line and internal cooling problems means opening it, which requires full depressurization and a technician. Call a technician if the sump over-temperature returns — the cause can be internal cooling or scavenge line problems that require teardown.
Verified against service documentation: Quincy QSI series (QSI standard controls) documentation for SUMP HAT (manualslib.com)