# AV40S low air will not clear

**URL:** <https://forum.avidcnc.com/t/av40s-low-air-will-not-clear/5377>\
**Category:** General Chat\
**Created:** [October 18, 2025, 11:18pm UTC](https://forum.avidcnc.com/t/av40s-low-air-will-not-clear/5377 "2025-10-18T23:18:26Z")\
**Posts on this page:** 5\
**Page:** 1

<div class="post-metadata">

**Author:** ![MBergeron](https://avatars.discourse-cdn.com/v4/letter/m/dc4da7/32.png) [@MBergeron](https://forum.avidcnc.com/u/MBergeron)\
**Post date:** [October 18, 2025, 11:18pm UTC](https://forum.avidcnc.com/t/av40s-low-air-will-not-clear/5377/1 "2025-10-18T23:18:26Z")

</div>

Just installed an avid 40S smart spindle and ex controller retrofit on a 4896 I am using my legacy 4hp VFD. I have 120 psi air at the spindle but I cannot get the error to clear in CNC 12. The fault stays lit and shows low pressure. The draw bar is functioning properly. Any ideas? I will call Avid Monday if I cannot figure it out.

---

<div class="post-metadata">

**Author:** ![grossmsj](https://yyz1.discourse-cdn.com/flex027/user_avatar/forum.avidcnc.com/grossmsj/32/4903_2.png) [@grossmsj](https://forum.avidcnc.com/u/grossmsj)\
**Post date:** [October 19, 2025, 2:03pm UTC](https://forum.avidcnc.com/t/av40s-low-air-will-not-clear/5377/2 "2025-10-19T14:03:21Z")

</div>

Did you try cycling the E-Stop? That is usually required to clear faults from the VFD box.

---

<div class="post-metadata">

**Author:** ![corbin](https://yyz1.discourse-cdn.com/flex027/user_avatar/forum.avidcnc.com/corbin/32/2800_2.png) [@corbin](https://forum.avidcnc.com/u/corbin)\
**Post date:** [October 19, 2025, 4:25pm UTC](https://forum.avidcnc.com/t/av40s-low-air-will-not-clear/5377/3 "2025-10-19T16:25:19Z")

</div>

I think you got the answer on the FB group– sounds like you missed the step to update the VFD settings. It all working now?

---

<div class="post-metadata">

**Author:** ![Eric](https://yyz1.discourse-cdn.com/flex027/user_avatar/forum.avidcnc.com/eric/32/3220_2.png) [@Eric](https://forum.avidcnc.com/u/Eric)\
**Post date:** [October 19, 2025, 6:14pm UTC](https://forum.avidcnc.com/t/av40s-low-air-will-not-clear/5377/4 "2025-10-19T18:14:03Z")

</div>

The AV spindles get air directly and have an air pressure sensor internally. When the spindle itself doesn’t get air it won’t operate.

The EX controller on your setup doesn’t communicate with the spindle. That air pressure indicator on your screen is for the laser, and for our future ATC

[![](https://canada1.discourse-cdn.com/flex027/uploads/avidcnc/original/2X/4/48b8db516605425d020cda04000d76410d920361.jpeg "Avid ATC Aux Box sneak preview") ](https://www.youtube.com/watch?v=cE9alUNoYTU)

When/If you upgrade to ATC the air pressure and all of the smart spindle sensors will be monitored by the EX control

---

<div class="post-metadata">

**Author:** ![MBergeron](https://avatars.discourse-cdn.com/v4/letter/m/dc4da7/32.png) [@MBergeron](https://forum.avidcnc.com/u/MBergeron)\
**Post date:** [October 19, 2025, 9:41pm UTC](https://forum.avidcnc.com/t/av40s-low-air-will-not-clear/5377/5 "2025-10-19T21:41:36Z")

</div>

Thanks for all the help. I configured the vfd and that cleared the alarm. However still had issues machine would not move. I found one of the ribbon cables had came un-plugged in shipping. Seems to be working correctly now!