10A AC fuse gets blown after a few minutes.

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  #1  
Old 08-12-14, 09:31 AM
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10A AC fuse gets blown after a few minutes.

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After a few minutes the 10 amp AC fuse is blown, see picture. Could the reason be the Belt Heater or the Discharge Pipe?

Thermostat goes dead after the blown fuse.

Hope it isn't the Compressor but an easy fix.

Any ideas welcome and already thanks for your reply.

Eddy
 
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  #2  
Old 08-12-14, 11:43 AM
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I'm curios what kind of unit this is. Make and model number?
 
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Old 08-12-14, 06:16 PM
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Looks like a multi-zone mini-split.
 
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Old 08-12-14, 07:02 PM
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Welcome to the forums..... Eddy of Dubai

Either one of those two items could cause the fuse to blow. You could try disconnecting one at a time to see if it's causing the short.

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  #5  
Old 08-12-14, 11:15 PM
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Sorry but I made some mistakes as this is not the right schematic of the unit. The unit is a Split AC from Fujitsu General AOG30A with the outdoor unit on the roof. We don't have heating in Dubai, its always hot here! :-) After some Googling I found the correct schematic of this unit. The fuse which gets blown is the 5A version. It seems its connected to L (phase) and point 3 of the terminal block than passing the relay on to the Belt Heater. Between point 1 and 3 of the terminal block there is a relay switch located on the Indoor Unit. However the fuse seems also protecting the Fan Motor via the return on 1. I'm not sure what the Belt Heater does but I could disconnect it without affecting normal operation, correct? Name:  arg30_model_kitchen.jpg
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  #6  
Old 08-13-14, 05:58 AM
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It sure appears the belt heater,just curious is this belt heater wrapped around the compressor?if so why are you using a crankcase heater in Dubai?
Geo
 
  #7  
Old 08-13-14, 08:37 AM
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I assume that these come standard with the unit. Most countries have winters just we don't. So what is this heater doing actually? ps not sure if it is wrapped around it. For that I will have to remove more panels.
 
  #8  
Old 08-13-14, 09:52 AM
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The heater is used in colder climates to drive refrigerant out of the oil in the compressor to help prevent compressor damage on start up.
I would disconnect it and see if that prevents the fuse from blowing,dose the unit run with the fuse out? Also check this out: Service Department:
Toll Free Service Hotline: (866) 952-8324
Local Service Hotline: (973) 575-0381
Service Fax: (973) 836-0449
Tech Support Email:
[email protected]
Technical Support is available from 8AM - 8PM EST.
Geo
 

Last edited by Geochurchi; 08-13-14 at 10:10 AM.
  #9  
Old 08-13-14, 10:11 AM
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I removed the connection to the Belt heather and can switch on. Without fuse all is dead.
 

Last edited by eddy_2012; 08-13-14 at 10:34 AM.
  #10  
Old 08-13-14, 02:22 PM
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Replace the fuse and leave the belt heater disconnected,did you try contacting their Tech support?
Geo
 
  #11  
Old 08-13-14, 04:57 PM
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The cap to the compressor is likely no good causing higher than normal amp draw
 
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Old 08-13-14, 06:57 PM
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The compressor is not fed from that fuse.
That fuse could be there strictly to protect the crankcase heater.
 
  #13  
Old 08-14-14, 01:38 AM
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I have placed a new fuse and disconnected the Belt Heater. So far so good! I tried to contact their tech support but they responded that I should contact the tech support in my region. I hope with disconnecting the Belt Heater nothing will get damaged in the long run.

Anyway thanks to all, this is really a great forum with a fast response. I'm impressed! Thanks again!

Eddy
 
  #14  
Old 08-14-14, 04:13 AM
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Should of looked at the diagram a little closer, sorry. The only thing on the circuit is the CCH.
 
  #15  
Old 08-18-14, 03:58 AM
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fuse still get blown!

So it might not be the Belt Heater as after two days running the fuse got blown again. I thought to replace the Fan capacitor which is 3.5uF 480v but couldn't find the right value and put in 3uF 400V. After installing almost immediately the fuse went bang. I measured the normal operation current which was about 1.5amp through the fuse. I replaced the FAN capacitor with the same from another normal working AC.

I measure about 374volt over the capacitor. When the fan hits on, the voltage goes high but can't see how high on my digital volt meter. After running for a few minutes the fuse went bang again. That was with the replaced capacitor of 3.5uF.

I'm out of options unless one of the two relays uses a lot of current, which I doubt.

Another cause could be the FAN itself?

What do you think?

With regards,
Eddy
 
  #16  
Old 08-18-14, 08:24 AM
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U need to find out what capacitance the fan motor requires.
Then install it & check the amp-draw of the fan motor to see if it is exceeding its rating.

If the nights are also warm U may not need the crankcase heater.
U can't just disconnect the CCH, U have to connect the conductor lines & bypass it; then U way have to use a lesser rated fuse to protect the fan motor.

As near as I can follow the diagram, it appears that either the CCH or the fan motor is pulling too many amps. That fuse also appears to feed a relay coil that could have a problem.
 

Last edited by HVAC RETIRED; 08-18-14 at 08:43 AM.
  #17  
Old 08-18-14, 10:11 AM
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Yes the nights are always warm here. In the diagram I don't see that I have to bypass the CCH. It just hangs between the L and the N via a relay switch. The L (Phase) comes from point 3 but is switched via point 1 coming from the indoor unit. I'm still not sure what cause the blown fuse as it doesn't happen immediately. I will have to do some more testing tomorrow morning. I doubt that a relay coil can draw a sudden high amperage. In the path of line I can also see an Outdoor Thermostat but how is it triggered? Understanding how it is connected it seems to switch the FAN in two speeds, high and low?
 
  #18  
Old 08-18-14, 11:13 PM
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Doing some testing this morning didn't give me any conclusion. The fuse blow so fast that the meter can't read it. The voltage over the fan capacitor stays steady 360 volts. Before all testing I had the main relay exchanged, the fan capacitor (already yesterday) and compressor capacitor, which all came out of a working AC standing next to it.

What I noticed is that the fuse blows with the outdoor cooling fan on but also when the system is not even on but in stand-bye mode! ???

When the cooling fan is blowing 1.5amp runs through the fuse. When the cooling fan is off there is still 0.8amp running through the fuse because I believe of the indoor fan?

So what is left, indoor or outdoor fan or PC board or still something other? Not sure how to change those without dismantling the whole thing!

Any further ideas from the panel?

With regards,
Eddy
 
  #19  
Old 08-19-14, 06:24 PM
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What other field wires are connected to L,N,3. N,1? Is there a wiring Dia. Of the indoor unit?
Geo
 
  #20  
Old 08-20-14, 07:41 AM
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I have made an simplified diagram. Between 1 and 3 sits a switch which is located at the indoor unit. This switch will trigger the compressor and fan located at the outdoor unit. Name:  Schematic_setup.jpg
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  #21  
Old 08-20-14, 02:59 PM
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Have you checked that PC board for any signs of damage i.e flash overs on the back of the board?are there any error codes on the remote or Tstat,I find it hard to believe it is the fan as that is switched through a relay controlled by the 5 amp fuse circuit.
Geo
 
  #22  
Old 08-20-14, 11:09 PM
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The PC board sits elevated via some plastic spacers on the metal housing. The distance is quite big so I don't think any flash overs is possible. The PC board seems to be OK as I have exchange it. Unfortunately I don't have a diagram of the PC board. If the fuse gets blown without that the system is even running, maybe it comes from one the parts connected to the board. The PC board itself is fused.
 
  #23  
Old 08-21-14, 05:14 AM
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Have you seen this site? Fujitsu General ARG30A Service Manual
Geo
 
  #24  
Old 08-21-14, 09:02 AM
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I do have the service manual but I found on the site of NODEVICE a more detailed service manual (file 0305G2272.pdf) and this one have the schematic diagram of the PC board. Nevertheless I have exchanged all electronic parts of the indoor unit, PC board etc and it still occurs. What puzzle me the most is that the fuse blows even when the manual switch is off at the indoor unit. looking at the drawing there is no path from L to N possible? Somehow there must be a leakage but if so you would expect that the automatic switch will be triggered instead that the fuse blows. I have updated the drawing to reflect the complete setup with in and outdoor manual switches plus the automatic switch. There must be a ghost somewhere annoying me, any cure for that? Name:  Schematic_setup_v2.jpg
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  #25  
Old 08-21-14, 09:39 AM
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Is this a 3phase unit,the one line Dia. Really doesn't help much,can that complete PDF be supplied?
Geo
 
  #26  
Old 08-21-14, 03:02 PM
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I see by the spec's it is single phase,it could make sense that the fuse blows with the inside unit off because it receives it's power from the outside unit,which terminals are the supply lines connected?
Geo
 
  #27  
Old 10-02-14, 10:28 PM
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Fixed!

After exchanging almost all parts with a working AC I still couldn't trace the fault. Had to bring in the expert and from his experience he actually found it quite fast. It was the indoor motor which was at faulty, internal wiring. I learned a lot of this exercise but funny enough I moved in meantime to another villa which are using LG AC's. Guess what I had so many issues due to lack of maintenance by the Landlord that I'm now digging in to the understanding how these work. What is strange is that with all four AC's I can't control the fan speed. I will open a new thread for this.

Thanks all for replying.
 
  #28  
Old 10-04-14, 12:46 PM
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Indoor motor at fault?

I don't see it. The indoor fan motor isn,t on the circuit after looking at the wiring schematic unless it's not the one to this unit. Only the relay and belt heater are in the circuit. Also, why would they have a fuse in the outdoor unit to protect the indoor unit?
 
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