new 1.1 compressor blowing 20A fuses

I am a mentor with Team 3329. We had to replace our compressor this year and went with the new 1.1 from AndyMark. It is connected directly to the PCM, but it is blowing the small 20A fuses on the PDB. We’ve checked the wiring into the PCM, and have even replaced the pressure switch. Any suggestions?

Drop us a line at We’ll take a look and get you running, whether by technical guidance or replacing it if it looks like a dud got through to you. :slight_smile:

Sent from my desk at AndyMark

Rule R56 allows the PCM to connected to a circuit breaker the PDB rather than the fused circuit. This will not fix a bad compressor but at least it will not blow the fuse that you VCM and robot radio is connected to.

How much current can the PCM handle in powering the compressor?

The Weidmuller PCM/VRM Connectors are protected by a single 20 amp fuse (shared between the two). So, the combined current of the PCM/VRM cannot exceed 20 amps (I’m guessing that the peak current draw of the VRM is about 4 amps). If you want 20 amps for the PCM alone, then you need to use a WAGO connector with its own 20 amp breaker.

The PCM has current limiting built in. It is rated for 17 amps continuous. It will allow more for the start up inrush. A bit of history: The older FRC compressors were famous for blowing fuses on the spike relay on start up. FRC allowed replacing the fuse with an 20 amp circuit breaker for that reason. I suspect you have a similar problem.

PCM tech specs here

Two questions:
If I go from compressor to a spike relay to PDB (20A fuse), would it work (no CAN connection)?
Would I damage the PCM if I try a 25 A mini fuse?

Question for you: Did you install the replacement filter that Andymark sent out? The smaller diameter black one that is deeper?

If so, did you cut about 3 threads off of the part that screws into the compressor?

If not, the length of that threaded stem is so long that it will bind into the compressor crankshaft. This could be binding the motor so much that you’re blowing fuses.

Thankfully I noticed this before installing the filter, and after some cutting and checking and cutting and checking, removing 3-4 threads safely clears the crankshaft, while still allowing a nice secure fit to the compressor.

Depends on what you use to control the relay.

This is a little troubling because that would be modifying a pneumatic component which isn’t legal.

By rule you can only connect the PCM to the 20 amp fuse connection (R52). I think it is a bad idea to power the PCM from there anyway since you allowed to power is from one of regular circuit breaker connections with a 20 amp circuit breaker (R56). Both cases specify 20 amp protection not 25. I don’t like spike relays. The PCM is a way better solution.

You can use lots of Teflon tape on the threads to avoid modifying a COTs pneumatic component. It not like there any pressure on the connection.


Thank you so much for pointing this out, we have been getting a few reports of blown fuses in 1.1 pumps and were not sure of the cause until now.

We will be sending an email to customers who received the replacement filters about this issue shortly recommending the use of a washer and/or PTFE tape to prevent the threads from interfering with the crank shaft without modification of the filter.

We just ordered and received a 1.1 pump yesterday. How do we know if we have the new filter?


  1. *Replace *the wiring to the PCM, and PCM to PDB
  2. Us a replacement fuse from a known good source, or at least a different one, and ensure that it is FULLY SEATED
  3. Double check that you are not exceeding the duty cycle of the compressor

Per the ‘modifying a pneumatic component’ discussion. How is a venting filter, which retains/controls/stores no compressed air at all, a pneumatic component? I am confused, please enlighten me.

It depends on weather it’s considered part of the compressor or not. You wouldn’t be allowed to modify the bolts that assemble the compressor yet they aren’t specifically pneumatic componens either.

Point of clarification: it is an inlet filter. I would have more concern with a venting filter since they are actually exposed to pressure. :] It is part of a COTs pneumatic component. Actually it would need to be part of the compressor since inlet filters aren’t a listed allowed component.

From a safety point of view: its trivial. From a strict reading of the rules you cannot modify pneumatic components.

Official AndyMark Update:

Everyone who purchased a 1.1 pump will end up, when all said and done, with the filter on the far left of this graphic.

Full disclosure this is the timeline:
We received 1 shipment of pumps with the filter on the left before kickoff. These sold out in a few weeks and we put the website out of stock until our second shipment arrived. We started sending out pumps from this second shipment without checking to see which filter was included. After a few days we realized that this second shipment had been packed with the grey filter on the right. As soon as we realized this we turned them off on the website, purchased the filter in the middle from a 3rd party and mailed out one per pump to everyone who had bought a pump that was from the second batch. When those people were taken care of we removed and threw out all the grey filters from boxes in inventory and replaced them with the 3rd party filter pictured in the middle. We then received a box of the small black filters from our supplier to make up for the ones they packed incorrectly. Today we realized the thread length issue and as of 4pm 2/10/17 if you order a 1.1 pump it will come with the small black filter pictured on the left.

Right now we are in the process of identifying everyone who ordered a pump from the second shipment and sending out the original, small, black, filter pictured on the left. We strongly recommend that once you receive the small black one you switch it. We have confirmed that there is not an interference problem with this filter as you can see in the pictures below:

Good filter installed on the back plate of the pump not protruding inside.

Bad 3rd party filter sticking past the back plate of the pump to the inside.

If you wish to use the larger black filter until your replacement arrives you should only install it 3 full turns. To assist in this you can wrap the threads in PTFE/“plumbers”/“Teflon” tape so that it will get tight before it bottoms out.

Thanks for the info! It would appear we got one of the bad filters. Awaiting the new one’s arrival!

Not legal.

Instructions show 10 and 20 amp mini fuses

R55. The fuses in the PDP shall only be replaced with functionally identical fuses (mini automotive blade fuses with values matching those printed on the PDP)

Inspection Checklist under “Electrical”, “Components”: “certain devices may be repaired with parts identical to the originals including PDP fuses”