Fan Commander (Vacon VFD) Troubleshooting Guide

Read the enclosure LED first

First thing: ask what the light is doing on the side of the enclosure. See if it gives you any clues.

Motor runs slow (new install)

Quick check: ask if it’s powered from a single-phase breaker panel. If yes, ask if it’s wired for low voltage. If they don’t know, the problem is likely up under the motor cover. Motor leads must be connected as per the low-voltage diagram on the motor.

1. Ask if it’s a 480v job (most likely not). If it’s 480v, check if the motor is wired as per the high-voltage diagram on the motor.
2. If it’s not a 480v job, ask if it’s wired for low voltage. If they don’t know what you are talking about, the problem is likely motor leads not connected properly.
3. 240v motor connections are usually:
   
   1 & 7 → connected to VFD’s U
   2 & 8 → connected to VFD’s V
   3 & 9 → connected to VFD’s W
   4, 5 & 6 → wire nutted together

   If it goes wrong, swap U & V (any 2 works).

4. If it’s still going slow after they verified connections are correct, navigate to M 1.4 Motor amps. If it’s above 5 amps and really not spinning, either there still is a mixed-up wire or the motor load is too high. The Vacon does not set the amps. Amps come from too heavy a load, miswiring, or a failing motor.

Doesn’t run the motor anymore

Screen still displays but the motor doesn’t go.

1. Check if 240v (or 480v if it’s 480) power is going to the VFD.
2. Check Mon 1.8 (bus volts).
3. Press the Loc/Rem button. It should make the arrow jump between I/O & keypad.

Fan speed varies a little at full speed

It’s the way they are designed. They actually overspeed until amps are maxed out. It’s not a problem unless speed is varying below 55Hz.

Brand newly installed motor doesn’t go (with Vacon VFD)

Randomly, a brand new fan doesn’t go. Typically the Ready indicator is missing. Reset the VFD to defaults:

1. Navigate to System 4.2 and set it to 1. The screen will blink and you will hear a click-click.
2. Power cycle and try again.

Previously running Vacon doesn’t spin motor – LED stays solid green

Problem: the VFD was giving an F1 overload fault but the LED was staying solid green. I think this was because we have the drive set to auto-reset from overloads.

I realized it had a fault because the customer said the screen had blinking lights (the backlight LEDs are visible when viewing from below).

I had him put it in Local mode (hand) so we could test it. The drive would always fault if the motor was connected. I had him disconnect the motor, then start the VFD. The drive would run and not fault with the load disconnected. Sent a replacement VFD. Don’t know if that’s what it really was.

Had him recheck the motor connections for any stray strands or loose wire nuts. He didn’t notice any.

Vacon VFD Fault 14

Fault 14 – VFD overheating. Most likely the internal cooling fan failed. Possibly we can repair it in our shop. The VFD will need to be replaced.

Vacon – stopping and starting on about a 15-minute cycle

If it’s several years old, there’s a good chance the internal cooling fan is not running. Check the fault codes:

1. Press Back/Reset 3x, then use the Down arrow to get the left arrow to SYS.
2. Press OK. The most recent fault code should display.

If it’s a Fault 14, then it is the cooling fan. We have had a 50% success rate in changing the fans.

Vacon – Fault 2 overvoltage fault

Set P1.21 to a value of 2. This will make the VFD try to ramp up the fan speed to draw down the voltage.

Undervoltage issues

Set P1.22 to a value of 1 – this is an undervoltage function. It will make the fan speed influenced by line voltage as well. Hopefully these 2 adjustments fix it. I feel there is a voltage regulation issue if they get over- and undervoltage issues.

Vacon – Fault 11 – Motor too hot

If it’s a new installation:

1. Make sure the motor is wired for low voltage (must always be wired for low voltage unless it’s a 480v install).
2. If it’s a new install, reset the VFD to its defaults.

If it had been running OK for months and just started:

Check if it’s going extra hard. Check Monitor V1.4 amps (actual amps) and compare to P1.4 motor amp setpoint. If actual amps are the same as the amp setpoint, it will eventually cause a Fault 11.

Resetting to defaults

1. Press Back/Reset 3x, then use the Down arrow to get the left arrow to SYS.
2. Press OK. Press the Right arrow 4x – it should display P4.2 (the left arrow must be at SYS).
3. Press OK and it should display a 0. Press the Up arrow to adjust it to a 1 – press OK. The backlight should blink and there should be some click-clicks – then the display will go to P1.3.
4. Turn power off until the display goes out, and then re-power. The VFD is now reset to its default parameters.

Vacon – Fault 10 – phase loss, voltage fluctuates too much

If they are single phase, the alarm can be turned off with P13.28 set to 1, which will make it just alarm rather than shut down.

If the VFD is 3-phase, double-check to make sure incoming power is good on 3 legs at the VFD terminal. If you can’t find any power anomaly, set P13.28 to 1. However, if there actually is an incoming power issue, it will shorten the VFD life or limit the top RPM.

Motor runs noisy and slow – new install

Wired wrong up at the motor leads. Have the customer turn power off to the VFD and recheck the wires at the motor connections, making sure they match the motor nameplate.

Vacon – Fault 1 high amps fault

1. Disconnect the motor wires from the VFD at the VFD. Then run the VFD with no motor wires connected. If the VFD still faults, the VFD is bad because it internally shorted.This can often be from a rubbed-through wire, usually at a bend where it enters the motor, or inside the motor cover, or a chafing point along a cord.
   
   The customer should patiently inspect the wiring because the VFD will self-destruct if it gets more than about [a few] shorts. VFD failures from high amps caused by arcing are not covered by warranty, because the brand new VFD will die as well.
2. If it’s a new installation AND you are sure all the wiring is good and you’re still getting an F1 fault, reset the VFD to its defaults (parameter SYS 4.2). We have found that sometimes settings are out of whack and it causes an overcurrent fault. To reset:
   1. Press Back/Reset 3x, then use the Down arrow to get the left arrow to SYS.
   2. Press OK. Press the Right arrow 4x – it should display P4.2 (the left arrow must be at SYS).
   3. Press OK and it should display a 0. Press the Up arrow to adjust it to a 1 – press OK. The backlight should blink and there should be some click-clicks – then the display will go to P1.3.
   4. Turn power off until the display goes out, and then re-power. The VFD is now reset to its default parameters.
3. Remove the 3 motor wires out of the VFD. Check that all strands of copper are laying evenly. Twist the strands and reinsert evenly. Check for any stray strands of wire at the VFD motor terminals or under the motor cover. If you can’t find anything, try running an alternative motor. It’s the process of elimination.

VFD display went out when control wires disconnected – possible bad VFD

Lightning can cause it. If the VFD seemingly stops working but the display is on: remove the control wires. If the display goes out even though the correct power is going to the VFD, the VFD internal power circuit is bad. Replace the VFD.

The reason the backlight and screen might partially work is the screen and keyboard are being backfed from the control wires.

Display off – but customer says VFD had power (any VFD)

Ask if they are checking voltage leg-to-leg going into the VFD itself, not before the breaker or back at their panel box. A leg-to-ground voltage reading will be erroneous.

Motor too noisy for in a shop – adjust P1.16

Adjust P1.16 higher.

How to change

Have the VFD powered but the fan not running:

1. Press Back/Reset several times.
2. Get the arrow on the left of the screen to PAR.
3. Press Enter (center button), then the Down arrow until it gets to 1.16, then press Enter again.
4. The screen will now display P1.16’s value. Press the Up arrow until it’s at 12.0, press Enter.

Reported pair of fans slows almost to a stop then takes off again

Like almost on a clock. New install. Wrong wiring on a Captain6. Had forward and reverse both connected to separate thermostat functions, which once both on shut down the fan. Forward and reverse at the same time means it will not run.

How to diagnose a Vacon not responding after a storm (or any time it had previously been running)

1. Go up to the VFD, find the black terminal block.
2. Take a picture of the control wires so you can remember.
3. Remove the wires off the bottom of the black terminal block, so the bottom is empty like this picture.
4. Turn power off. Find 2 short pieces of wire:
   
   Jump red wire → brown
   Jump white wire → blue
5. Now the fan should run whenever power is applied.

If the fan starts and runs, the VFD most likely is good. If it does not start:

1. Check to make sure the little arrow is above I/O.
2. Make sure 240v is on the top row of the breaker (if 240v power).
3. Make sure there is no arrow at fault (upper right corner of screen).

Replace the VFD if you have ruled out the above.

12-fan installation – after a storm

Had a storm. 3 fans quit immediately. 7 stopped a day later.

1. Check if the temperature controller is sending a 0–10v signal.
2. Go to each VFD and check if each VFD can run in keypad mode.
   • Can’t run – VFD needs replaced.
   • Can run motor in keypad mode – test if it can run from control signals.

Disconnect all wires going to the vent control. Jump wires:

As long as the VFD has an arrow above I/O and the VFD is jumped as above, it should try to run the motor full speed (as long as there are no motor or wiring issues). Swap the drive or use process of elimination.

Fan not running – arrow at Keypad instead of I/O

Fan not running. The arrow on the bottom of the screen was at Keypad. The arrow needs to be at I/O to run from the temperature controller.

Press Loc/Rem once. Each press flips it between Keypad and I/O.

Earth Fault – Vacon Fault 3

Earth faults are when the VFD detects electricity shorting to ground. Too many earth faults ruin a VFD. Always figure out what’s happening; do not continue use until the problem is found.

Problems that cause it, in order of likelihood

1. Rubbed wires under the motor cover.
2. Nicked or damaged VFD-to-motor wires – check for any rubbed-through wires.
3. Bad VFD.
4. Bad motor.

Process of elimination – if you have an insulation meter

Disconnect the motor’s wires at the VFD! Put the insulation tester’s probes between the motor wires and the motor frame. Press and hold the Fluke test button for at least 3 seconds. You should be able to keep at least 1000v. If you can’t keep voltage, check the test wires and motor separately.

Process of elimination – no insulation tester

Test in this sequence.

• Test 1: disconnect motor leads from the VFD – start the VFD – see if it faults again. If it earth-faults again when started with no wires attached, the VFD is bad.
• Test 2: connect the motor wires to the VFD again but disconnect at the motor cover. If it earth-faults again when started, the wires are bad – replace the wires between the motor and VFD.
• Test 3: connect the motor wires to the VFD again but reconnect the motor. If it earth-faults again when started, the motor likely is bad.

However, there is still a chance the VFD is bad. Swap VFDs only after you have ruled out any short circuits. If you missed it, you might ruin a brand new VFD as well. This has happened. It’s not warranty.

Debugging a Fan Commander system not running

Tools required

• Voltmeter with AC & DC, plus a certain level of proficiency using a voltmeter.
• #2 Phillips screwdriver.
• Small flat screwdriver.
• ¼ hex nut driver (if replacing a VFD).
• 5/16 hex nut driver (if replacing an entire backplate).
• Camera to take pictures of how wires were connected.

All fans not working – control power test

Fan Commander screen blank. Assumes multiple fans controlled by a single Fan Commander system.

Test 1

Check for 24vdc between 0v and 24v+.

• If the display is off and there is 24vdc between terminals 0v- & 24+, then the boards are likely bad. Replace the boards.
• If there is no voltage between terminals 0v- & 24+, disconnect the wind sensor. If 24vdc voltage appears only if the wind sensor is disconnected, replace the wind sensor.

Test 2

Disconnect the wires from 0v and 24vdc. Check the voltage between the wires that previously connected to terminals 0v- & 24vdc. If 24vdc shows up on the wires only if disconnected, replace the Fan Commander boards.

Test 3

Assumes Tests 1 & 2 are already done. Go to the fan’s VFD. Open the enclosure. Check if the VFD has power.

• Check for 240 vac between the top screws of the circuit breaker. If no power, cycle the circuit breaker – go figure out why the electric is off.
• If the VFD has 240 vac power and its display is nonfunctional, replace the VFD.

Test 3 (continued) – control wires

Assumes the unit is powered correctly. Check for 24vdc between the Black and White control wires.

• If no voltage, disconnect the black and white wires from the top of the terminal block. If there is no voltage between the disconnected black & white, replace the VFD.
• If 24vdc is present between the disconnected Black and White control wires, then the VFD is likely OK.

Repeat Test 2 and 3 at every VFD.

Check the cable’s individual conductors by disconnecting each conductor at all ends. Then use an ohm meter to make sure there’s no continuity between any of the control cable’s conductors. Also check continuity through the wires by making a pair and checking continuity across the open end.

All fans not working – Fan Commander illuminated

If all fans are not working but the Fan Commander’s display is illuminated, check the 0–10v speed signal.

Test 1

Set the Fan Commander’s speed knob to 75%. Check if approximately 7.5vdc is across terminals 10V & 0V.

• If the voltage matches the knob’s position, the Fan Commander is likely working.
• If no voltage: disconnect the wires connected to 10v & 0V. If voltage appears between terminals 10V & 0V with the wires disconnected, then the Fan Commander speed output is working. If still no voltage, then the Fan Commander needs replaced.

Test 2 – Forward signal

With the knob at 75%, check for 24vdc between 0v and Forward & Reverse.

• If no voltage, test the voltage between 0v & common. If still no voltage, check your meter.
• If there is voltage, then the Fan Commander is good – check your wiring going up to the fan. Make sure the same voltage is at both ends of the wire.

At least 1 fan is functioning – signal tests

If there are at least 2 fans in the system and at least one of them responds correctly to the Fan Commander:

Speed signal tests

Test up at the VFD. Check the line voltage AC between the top screws of the VFD. Line-to-ground measurements are useless – it must be line-to-line volts.

With the Fan Commander set to 75%, check the DC voltage between Brown & Black.

• If no voltage, check the control wires. (We know the signal is OK at some point because the other fan responds correctly. The only difference could be the wires if there’s no voltage here.)
• If the correct voltage is between Brown & Black, see the next test for the RUN signal.

Run signal tests

If there are at least 2 fans in the system and at least one of them responds correctly to the Fan Commander:

With the Fan Commander at any speed other than OFF, check the DC voltage between Blue & Black.

• If not 24vdc, check the control wires. (We know the signal is OK at some point because the other fan responds correctly. The only difference could be the wires if there’s no voltage here.)
• If 24vdc between Blue & Black, make sure you did the speed signal test. Possibly change the VFD – however, see the checklist below for reasons the fan might not run and yet the VFD is OK.

Control signals all tested correctly, but the fan still isn’t working – checklist

• Is the VFD actually trying to run the fan but the amps are too high?
• Is the motor wired correctly – wired for low voltage if it’s 240v?
• Check to make sure the VFD is not in local mode.
• Line voltage too low (below 200VAC for 240v units).
• Make sure the fan motor is connected.
• Make sure the belt is on the fan.

Check the voltage of the VFD output from leg to leg – it should be the same. (However, the speed must be stable between measurements.) If it is not the same with a stable Hz, the VFD likely needs replaced.

Troubleshooting greater than 10v on the Brown control wire

Problem: it appears as if the Fan Commander is putting out more than 10v.

Test #1

1. Disconnect all wires from the Fan Commander’s 10v (leftmost terminal).
2. Set the Fan Commander knob to 75%.
3. Test for DC voltage between the 10v and 0v terminal. Put the meter’s red lead on 10v and the black lead on 0v. You should get within a volt of what the display shows (i.e. 7.5v for 75%).
4. Turn the knob up and down; the voltage should move with the knob.

• If the voltage does not move with the knob, the Fan Commander output is ruined. Replace it.
• If the voltage does move with the knob, go to Test 2.

Test #2 – check each VFD

With the 10v wire at the Fan Commander still disconnected, disconnect the Brown wire from the top of the terminal block. Measure the voltage between the now-loose brown wire and the black wire. If it measures more than 0.1 volts, the VFD is ruined. Replace it.

Test 3

Have all the brown wires loose from the terminal block. Have the 10v terminal disconnected in the Fan Commander. If you can still read voltage in the now totally disconnected wire, the wire is bad and needs replaced.

Control wire connections

Optional LED indicator. Not used on 2019 or earlier units.

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