What does HIGH DISCH TEMP mean on a Sullair ShopTek controller?
Short answer: High discharge temperature warning/trip. If your Sullair ShopTek Controller is showing HIGH DISCH TEMP, 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 controller displays a warning when discharge temperature exceeds 225°F (107°C), and shuts down with a STOP fault when the set limit is exceeded. Causes: ambient above 105°F (40°C), low fluid level, thermal valve fault, dirty cooler fins, or a failed temperature sensor.
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?
- Ambient above 105°F (40°C)
- Fluid level low
- Thermal valve fault or dirty cooler fins
- Failed temperature sensor
- Warning shows above 225°F; the STOP fault lands at the set limit
Can you fix it yourself?
Often, yes — ventilation, fluid top-up after cooldown, and cooler cleaning clear most of these; reset and watch the displayed temperature.
Step by step — what to try, in order:
- Improve ventilation around the compressor if the room is hot
- With the unit stopped and cooled, replenish compressor fluid to the proper level
- Clean cooler fins and fan blades
- After cooldown, reset and restart while watching the displayed temperature
When do you need a technician — and why?
A repeating trip means the thermal valve or temperature sensor likely needs replacement — fluid-circuit and sensor work for 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 HIGH DISCH TEMP mean on a Sullair ShopTek Controller?
High discharge temperature warning/trip. The controller displays a warning when discharge temperature exceeds 225°F (107°C), and shuts down with a STOP fault when the set limit is exceeded. Causes: ambient above 105°F (40°C), low fluid level, thermal valve fault, dirty cooler fins, or a failed temperature sensor.
Can I fix HIGH DISCH TEMP on a Sullair ShopTek Controller myself?
Often, yes — ventilation, fluid top-up after cooldown, and cooler cleaning clear most of these; reset and watch the displayed temperature.
When does HIGH DISCH TEMP on a Sullair ShopTek Controller need a technician?
A repeating trip means the thermal valve or temperature sensor likely needs replacement — fluid-circuit and sensor work for a technician. Call a technician if the trip repeats — the thermal valve or temperature sensor likely needs replacement.
Verified against service documentation: Sullair ShopTek Controller documentation for HIGH DISCH TEMP (best-aire.com)