❄ Compressor Code Lookup
Home › Sullair › MOTOR OVERLOAD
Sullair ShopTek Controller · MOTOR OVERLOAD

Why does my Sullair ShopTek compressor trip on motor overload?

Short answer: Drive motor overload trip. If your Sullair ShopTek Controller is showing MOTOR 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 motor overload relay tripped due to a power overload in the motor — low line voltage, incorrect configuration, or load pressure set above the compressor's limit are documented causes.

Which machines show this?

Sullair's ShopTek line of smaller shop-duty rotary screw compressors — the ST-series packages aimed at garages, tire shops, and light manufacturing — with the compact ShopTek controller. Its display is terse: faults appear as short all-caps messages such as HIGH DISCH TEMP, PR XDCR FAULT, RTD FAULT, and A-O SEPARATOR, mixing hard shutdowns with service reminders in the same format. Discharge temperature warns above 225 °F and shuts down at the set limit. Practical tip: on these units learn which messages are reminders (A-O SEPARATOR is a service interval, not a failure) and which are trips — resetting a reminder without doing the service just deletes your warning, not the problem.

What causes it?

  • Low line voltage into the motor
  • Load pressure set above the compressor's limit
  • Incorrect machine configuration

Can you fix it yourself?

Partly — cool-down, one reset, verifying the load pressure setting, and flagging low building voltage to the power company.

Step by step — what to try, in order:

  1. Let the overload element cool, then reset
  2. Verify load pressure is set below the compressor's limit
  3. If building voltage is low, consult the power company
One reset is diagnosis, repeated resets are damage. If the same fault returns after a single reset, the underlying condition is real — stop resetting and deal with the cause.
Safety: Starter enclosure contains line voltage — leave internal checks to a professional.

When do you need a technician — and why?

Motor amps, starter contacts, and connections need checking with instruments in a line-voltage enclosure — electrician or service tech on a repeat trip.

When to call: Call an electrician or service tech to check motor amps, starter contacts, and connections if it trips again.

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 MOTOR OVERLOAD mean on a Sullair ShopTek Controller?

Drive motor overload trip. The motor overload relay tripped due to a power overload in the motor — low line voltage, incorrect configuration, or load pressure set above the compressor's limit are documented causes.

Can I fix MOTOR OVERLOAD on a Sullair ShopTek Controller myself?

Partly — cool-down, one reset, verifying the load pressure setting, and flagging low building voltage to the power company.

When does MOTOR OVERLOAD on a Sullair ShopTek Controller need a technician?

Motor amps, starter contacts, and connections need checking with instruments in a line-voltage enclosure — electrician or service tech on a repeat trip. Call an electrician or service tech to check motor amps, starter contacts, and connections if it trips again.

Verified against service documentation: Sullair ShopTek Controller documentation for MOTOR OVERLOAD (best-aire.com)

Other Sullair ShopTek Controller codes

HIGH DISCH TEMP
High discharge temperature warning/trip
PR XDCR FAULT
Pressure transducer fault
RTD FAULT
Temperature sensor (RTD) fault
HIGH PRESSURE
Operating pressure above shutdown limit
A-O SEPARATOR
Air/oil separator service reminder
E-STOP
Emergency stop active