What does the PS1 outlet pressure sensor error mean on a Quincy QGS?
Short answer: Outlet pressure sensor fault. If your Quincy QGS 20-30 (INFOLOGIC controller) is showing Outlet pressure sensor error (PS1), 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 shuts the compressor down on an error of the outlet pressure sensor; a disconnected pressure transmitter (PS1) is indicated by the flashing general alarm LED with pictograph.
Which machines show this?
Quincy QGS 20-30 hp rotary screw compressors with the compact INFOLOGIC controller, including tank-mounted and integrated-dryer variants. There are no numbered fault codes on this controller: it communicates with LEDs and pictographs — a flashing temperature symbol, a motor symbol, an e-stop symbol, a service wrench — plus small scrollable screens (like d.06 for service-timer hours). Identifying a fault means reading which pictograph is lit or flashing and whether the alarm LED is steady (warning) or flashing (shutdown). Warnings clear themselves when the condition passes; shutdowns need the cause corrected and the unit reset. Larger QGS machines from 40 hp up use the different Airlogic2 controller instead.
What causes it?
- Pressure transmitter PS1 disconnected from the controller
- Sensor or wiring fault killing the outlet pressure signal
- A transient that a single power cycle may clear
Can you fix it yourself?
One power cycle, then stop. The controller shuts down on this error because it has lost its pressure signal — repeated restarts won't bring the sensor back.
Step by step — what to try, in order:
- Note the alarm indication shown on the display
- Power the unit down and back on once to see if the sensor signal returns
- Do not keep restarting if the fault persists
When do you need a technician — and why?
The manual restricts sensor and wiring diagnosis to qualified personnel; PS1 sits on the pressurized outlet circuit and connects into the control cabinet, touching both hazard zones.
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 Outlet pressure sensor error (PS1) mean on a Quincy QGS 20-30 (INFOLOGIC controller)?
Outlet pressure sensor fault. The controller shuts the compressor down on an error of the outlet pressure sensor; a disconnected pressure transmitter (PS1) is indicated by the flashing general alarm LED with pictograph.
Can I fix Outlet pressure sensor error (PS1) on a Quincy QGS 20-30 (INFOLOGIC controller) myself?
One power cycle, then stop. The controller shuts down on this error because it has lost its pressure signal — repeated restarts won't bring the sensor back.
When does Outlet pressure sensor error (PS1) on a Quincy QGS 20-30 (INFOLOGIC controller) need a technician?
The manual restricts sensor and wiring diagnosis to qualified personnel; PS1 sits on the pressurized outlet circuit and connects into the control cabinet, touching both hazard zones. Call a technician if the fault does not clear — sensor and wiring diagnosis is restricted to qualified personnel per the manual.
Verified against service documentation: Quincy QGS 20-30 (INFOLOGIC controller) documentation for Outlet pressure sensor error (PS1) (airenergy.com)