goodman blowing fuse

Old 07-18-08, 10:44 AM
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goodman blowing fuse

I just finished building my house, and I am having an AC issue. I can't get the original contractor out because I already won a court judgment against them and they aren't even paying me back yet (lots of issues). I am not a self-proclaimed HVAC expert, but I did GC my home construction so I am pretty comfortable with electrical.

I had a pro come in and finish up the original hack job installation, but I'm having an issue right now and my pro is on vacation. I have a goodman GMV95 furnace with an SSX16 4-ton unit, IAQ Stat, and 300DD HRV. I live in Michigan so I haven't used the AC much up until now. Just recently, on really hot days when the AC runs often, it will somtimes start up very loud, sounding like a garage air compressor. When this happens, somtimes it will blow the 3-amp fuse on the furnace. I have checked the 24V wiring from the furnace to my IAQ and the condensor, and there are no shorts.

Does anyone have any suggestions? Could it be acting this way if it is low on R410a? The condenser is about 60 days old.

thanks in advance,
Old 07-18-08, 10:54 AM
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Blowing fuse

The refrigerant would not have anything to do with blown 3 amp fuses. That fuse is strictly for control voltage. What size is the low voltage wiring? It should be at least 18 AWG.
Old 07-18-08, 04:10 PM
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I am not sure of all the nuances when certain things are not right, but the way I try to handle such situations, being in the trade of general maintenance, is to at least see if there is stuff I that I CAN test for, that at least IT is right?

For example, maybe you are not getting full 240 volts through the contactor. Or maybe the capcitor is suspect.

Maybe the 3 amp fuse blowing in your interior handler/furnace is a coincidence - a totaly separate issue, having to do with the handler and not the condensor unit.

I can't see how anything electrically wrong could cause your (relatively new?)compressor out there to sound like some air compressor, unless maybe it is trying to run on low volts, as I mentioned (simply a guess on my part), or was perhaps even HIGH on pressure. Are you turning the unit off and back on right away when you are checking things out? I know this is bad to do on wall/window units, but am not real sure about the split system units, but I always err on the side of caution and wait say 10 minutes.

Have you checked the amp draw around one of the compressor wires with an amp meter when it runs, both with that awful sound and when that awful sound is not there?

As a final thought, it could be possible I suppose that your new unit came with a defective compressor? Like someone at the factory did not get something tightened good inside, or something. But obviously to consider this, one would have to make sure proper voltage to compressor with capacitor doing it's job, and perhaps proper pressure.

Last edited by ecman51; 07-18-08 at 04:19 PM. Reason: added more
Old 07-21-08, 05:38 PM
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did some more internet searching, seems like some other people are having problems with the system running the compressor too much. It does seem like the system comes off and on a lot! the compressor delay was set to 5 minutes, but the cooling cycles per hour was set to auto. I dropped that back to 2, we'll see what happens.

Old 07-22-08, 04:26 AM
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Loose Connection

Providing the unit is not overcharged...(Something you cant check)

Compressor Noise * A "simi" loose connection will cause this - Check all the main power conections at breaker and unit outside ( The Disconnect) and inside the unit (Outside)at the capacitor/contactor ( WITH POWER OFF - *Also please short the capacitor out (Before touching it) with a screw driver across its posts to keep from shocking you since it stores energy even with power off!) Check for looseness at every connection including directly on the compressor terminals!. If it is loose at any main power connection - the compressor having to use alot of power to start, would be sounding and jerking about if it were not getting the proper electron flow (Because of resistance through a bad connection) to windings - (Voltage drop). You said it was "sometimes"... my first thought was overcharge but "sometimes" makes me think its intermitten electrical/connection.

The best approach is to tighten every connection with a screw driver - and smash every post connector with needlenose plyers then reapply connector/wire to Post/Component once smashed - instead of checking for loosness with you fingers because what is loose to the compressor, may not seem loose to you!

* Also Please check Crank Case heater - (Since you live in the northern states - Cool nights/Hot days) If it is the initial start that the noise happens - It could be Liquid Refrigerant settled in the oil of the compressor overnight. When started up, the compressor must eat this liquid until it is all converted to a vapor by the heat of the oil and compressor - If this is happening, that is VERY BAD!. It means it will wear out your compressor prematurely ( I wont go into why at this juncture). The fix is - check the "crankcase heater" - electrical connections for tightness and operability - opens/Shorts,... if it has a crankcase heater! If it does not - Have one installed right away!

As for the 3 amp fuse Blowing* ( Completely separate problem) - It is most likely a short in the control wiring - Simply change the color wire(yellow) to a different color that is not being used between the AirHandler/Furnace and the A/C outside And the Tstat - Make sure all three are using the same color wire! For instance - Change the "Yellow" (Normally the cool control wire) to Purple at all three places. Since it shorts out in cooling - it would most likely be the yellow wire - if it continues - Put it all back the same and change the green wire to purple...and so on,... until it no longer blows the fuse!

These Are All things I would be looking for... if I were working on your system!

Last edited by The Real Deal; 07-22-08 at 05:31 AM.

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