Why did my Quincy QGD compressor trip on motor overload?
Short answer: Drive motor or fan motor overload. If your Quincy QGD 40-60 / QGS 40-100 (Airlogic2 controller) is showing Motor overload shutdown, 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 is stopped on overload of the drive motor; air-cooled units also stop on overload of the fan motor (overload relay F21 or fan overload F15 open). The controller's Reset button clears a motor overload after the cause is fixed.
Which machines show this?
Quincy QGD 40-60 hp and QGS 40-100 hp rotary screw compressors with the Airlogic2 display controller, including Full Feature packages with the integrated refrigerated dryer. Like Quincy's smaller INFOLOGIC machines, these display icons and text messages, not numbered fault codes — a lit alarm LED means a warning, a flashing one a shutdown, and the specific condition is spelled out on the controller's screens and logged in the Event History menu. Warning and shutdown levels for temperatures are programmed values with factory settings, so your machine's exact trip points can differ. Two habits the manual insists on: the emergency stop does not make the machine voltage-free, and service timer changes go through the authorized distributor.
What causes it?
- Drive motor overload relay F21 opened after the motor ran hot
- On air-cooled units, fan motor overload F15 — often a blocked or dirty fan and cooling path
- A fan wired to rotate the wrong direction, which causes overtemperature and fan overloads
- Voltage, phase, or wiring faults when the trip repeats
Can you fix it yourself?
Cool the motor, check room conditions, clear the fan path with power off, use the Reset action button, and try one restart. A second trip ends the DIY portion.
Step by step — what to try, in order:
- Let the motor cool and check compressor-room temperature and ventilation
- For fan overload: with power off, check that the fan and cooling air path are not blocked or dirty
- Use the controller's Reset action button to clear the overload, then restart once
- If it trips again, stop and call for service
When do you need a technician — and why?
Overload relay, phase sequence relay, and fan rotation checks are high-voltage electrical work — wrong fan rotation in particular is an electrician fix, not a maintenance tweak.
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 shutdown mean on a Quincy QGD 40-60 / QGS 40-100 (Airlogic2 controller)?
Drive motor or fan motor overload. The compressor is stopped on overload of the drive motor; air-cooled units also stop on overload of the fan motor (overload relay F21 or fan overload F15 open). The controller's Reset button clears a motor overload after the cause is fixed.
Can I fix Motor overload shutdown on a Quincy QGD 40-60 / QGS 40-100 (Airlogic2 controller) myself?
Cool the motor, check room conditions, clear the fan path with power off, use the Reset action button, and try one restart. A second trip ends the DIY portion.
When does Motor overload shutdown on a Quincy QGD 40-60 / QGS 40-100 (Airlogic2 controller) need a technician?
Overload relay, phase sequence relay, and fan rotation checks are high-voltage electrical work — wrong fan rotation in particular is an electrician fix, not a maintenance tweak. Call a qualified technician on a repeat trip — checking the overload relay, phase sequence relay, and wiring is high-voltage electrical work.
Verified against service documentation: Quincy QGD 40-60 / QGS 40-100 (Airlogic2 controller) documentation for Motor overload shutdown (compressorworld.com)