Why did my Sullair ShopTek compressor trip on high pressure?
Short answer: Operating pressure above shutdown limit. If your Sullair ShopTek Controller is showing HIGH PRESSURE, 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 compressor operating pressure exceeded the set shutdown limit — caused by a faulty pressure sensor, a control/valve problem, or a faulty unload solenoid valve.
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?
- Faulty pressure sensor
- A control or valve problem keeping the unit loaded
- Faulty unload solenoid valve
Can you fix it yourself?
Partly — blow down, confirm setpoints match the machine's rating, restart once, and watch whether it unloads at target.
Step by step — what to try, in order:
- Stop the unit and let it blow down
- Confirm the pressure setpoints match the machine's rating
- Restart once and watch whether the unit unloads at the target pressure
When do you need a technician — and why?
A recurring trip needs the unload solenoid, control valves, and pressure sensor checked by service — overpressure events are not to be reset repeatedly.
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 HIGH PRESSURE mean on a Sullair ShopTek Controller?
Operating pressure above shutdown limit. The compressor operating pressure exceeded the set shutdown limit — caused by a faulty pressure sensor, a control/valve problem, or a faulty unload solenoid valve.
Can I fix HIGH PRESSURE on a Sullair ShopTek Controller myself?
Partly — blow down, confirm setpoints match the machine's rating, restart once, and watch whether it unloads at target.
When does HIGH PRESSURE on a Sullair ShopTek Controller need a technician?
A recurring trip needs the unload solenoid, control valves, and pressure sensor checked by service — overpressure events are not to be reset repeatedly. Call service to check the unload solenoid, control valves, and pressure sensor if the trip recurs.
Verified against service documentation: Sullair ShopTek Controller documentation for HIGH PRESSURE (best-aire.com)