What does RTD FAULT mean on a Sullair compressor?
Short answer: Temperature sensor (RTD) fault. If your Sullair ShopTek Controller is showing RTD FAULT, 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 temperature sensor has failed or its connection has come loose; the machine stops because discharge temperature can no longer be monitored.
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?
- Temperature sensor (RTD) failed
- Sensor connection loose or wiring damaged
Can you fix it yourself?
Sometimes — check the connector and visible wiring with power locked out, then one restart.
Step by step — what to try, in order:
- With power locked out, check the sensor connector and visible wiring for damage
- Reset and attempt one restart
When do you need a technician — and why?
If the fault persists, the RTD must be replaced before the machine runs — operating without discharge-temperature protection is how airends die.
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 RTD FAULT mean on a Sullair ShopTek Controller?
Temperature sensor (RTD) fault. The temperature sensor has failed or its connection has come loose; the machine stops because discharge temperature can no longer be monitored.
Can I fix RTD FAULT on a Sullair ShopTek Controller myself?
Sometimes — check the connector and visible wiring with power locked out, then one restart.
When does RTD FAULT on a Sullair ShopTek Controller need a technician?
If the fault persists, the RTD must be replaced before the machine runs — operating without discharge-temperature protection is how airends die. Call a technician to replace the RTD if the fault persists — running without temperature protection is not safe.
Verified against service documentation: Sullair ShopTek Controller documentation for RTD FAULT (best-aire.com)