Goodman heat pump blows fuses


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Old 12-15-17, 12:27 PM
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Question Goodman heat pump blows fuses

I also have blowing fuse problem. I have goodman unit with furnace inside and and outdoor AC/heat. The first time it blew fuse, I replaced the fuse and it lasted for couple of days. The second and the third time it lasted much shorter.
The fuse is okay if I don't turn heat on. If I turn heat on, then the 3amp fuse blew within 3 or 5 minutes. I changed a new capacitor and a new contactor coil. The problem is still there, I measured the resister of the condenser fan and get 32.8; 50.7, and 83.2 Ohm. Could it be the problem with the condenser fan or the defrost board? What should I check next? Any suggestion is appreciated? I still have one unit upstair running but my first floor is too cold now.
 
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Old 12-15-17, 12:57 PM
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Welcome to the forums Ryan.

With a complicated problem it's always better to have your own thread.
Once you respond to this..... this will become a new thread.

Help us here.... we cannot see what you have.
What fuse are you replacing ?
This sounds like a heat pump system.
What brand is the outside condensor ?
Have you tried to see if the system runs ok in A/C ? (outside weather dependent)

It will not be a fan problem.
Defrost board possibly.
Contactor....a slight maybe
If it's a Ruud or Rheem unit..... great chance of reversing valve or valve wiring problem.
 
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Old 12-15-17, 03:02 PM
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Hi PJmax, for some reason I cannot create a new threat. I found Dave's problem is similar to mine so I just ask in my comment.
Yes, I have a problem with heat pump. It is a Goodman heat pump/AC unit outside.
The fuse that I replaced is the 3amp fuse located in the air handler.
From your suggestion for Dave, I measured the resistor of the yellow wire to ground in my indoor furnace get a blank result.
So I guess that I have a short some where. I swap the green line from the condenser to the yellow line and still have zero resistor. I also rewire the thermostat (cut a very short amount) and there is no resistor. I don't really know what to try next. Can a bad defrost board cause the short problem to the yellow wire? Thank you very much for your suggestion.
 
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Old 12-15-17, 04:07 PM
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Blank result ??

When in ohms mode..... the meter should show OL or some other letters like that. When you touch the probes together you should get a reading close to 0 ohms.
0 ohms is a dead short.

So when you check the yellow wire to ground and see no change at all..... you're not connected. If you see any meter change..... read the results.

Go out to the Goodman condensor. Locate where the thermostat wiring connects to the condensor. Locate and open the yellow wire splice or connection. You want the yellow wire coming from inside the house connected to nothing. Turn the stat to heat. Let it sit. See if the fuse still blows. Let us know.

I'm online here until at least midnight eastern.
 
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Old 12-15-17, 04:20 PM
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Thank you PJmax. Do you mean disconnect the low voltage yellow wire to condenser? I am not sure if the wire is from the thermostat.
Regarding the yellow wire connection in the furnace, there is no ohm reading. I tested the AC and it seems fine (run for 5 mins). However, when I turn the heat on, it blew fuse again. I haven't tried disconnect the yellow wire yet. I will try it soon.
 
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Old 12-15-17, 04:48 PM
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If the A/C is ok..... and the outside condensor was running.... the yellow wire is not the fault.

Do you have a humidifier ? If yes.... let me know and do nothing.
If no.... set the thermostat to one degree over room temperature and try the heat again.
 
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Old 12-15-17, 05:23 PM
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Well, the AC was fine for 5 minutes, then I switched to heat and it blew fuse after 3 mins. So I am not even sure if the AC is okay. It wasn't a good AC test coz the temperature outside is even colder than the mininum temperature that I can set in AC. I disconnected the yellow line and turned it to heat. It has been running for 5 minutes. Let's see if it can hold for another 5 minutes. I will let you know what will happen in 5 mins.
 
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Old 12-15-17, 05:34 PM
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It has been running for about 10 minutes. However, I only set it 1 degree higher than room temperature. I will set it a bit higher and see if it will blow fuse.
 
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Old 12-15-17, 06:12 PM
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Hi Pete, it is still running. I forgot to mention that I have no humidifier. So I guess the yellow line is the fault. It takes so long to heat up. Can it heat the home if I disconnect the yellow line?
What should I do with this yellow line? Do I have to do something or just leave it unconnected like it is now?
 
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Old 12-15-17, 07:37 PM
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Hello, could you tell me what does the yellow line do? Can the systems heat the house if the yellow line to the condenser left open? Sorry for bugging you.
 
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Old 12-15-17, 07:47 PM
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No problem.... I'm a service tech and sometimes business calls.

OK. You have it disconnected at the condensor... correct ?
That yellow wire powers the contactor that starts the fan and compressor. Since you don't get an instant short.... it appears your contactor coil is shot. You can use a flashlight to see if it's burned. Be sure to turn the power off to the condensor before poking around in there.

If you set the thermostat up a few degrees and leave the yellow wire disconnected.... the electric heat should run and give you heat. It may take several minutes to come on.

Do you know what the contactor looks like ?
It's the relay type device in the same wiring area where the thermostat wiring connects.

This is a mirror image of your problem. Contactor in post 2.
heat-pumps-electric-home-heating / 24v-secondary-3amp-fuse-blows-heat-cold
 
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Old 12-15-17, 08:11 PM
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I changed a new contactor coil yesterday so I am not sure if the short still come from there.
Is this correct that the compressor doesn't work if the yellow wire is disconnected?
I saw the yellow wire from inside connect to a wire that go to some coil near reversing valve I think. I will need to look carefully tomorrow. It is cold and dark now
 
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Old 12-15-17, 08:43 PM
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Yes... that's what I posted.

Yellow is 24 vac to the contactor. No 24v..... no contactor..... no compressor or fan.
Goodman uses 24v on the reversing valve for cooling so that won't be your problem.

If you just put a new contactor in then it shouldn't be a bad coil.

Here's the crux of the problem..... you have something causing a short on the yellow line to ground. You need to find it. You need need to break connections in the yellow line until you find the short. Most likely place is outside between the house and the condensor.

The yellow wire that enters the condensor MAY go thru a low pressure and high pressure switch first. So trace the yellow wire from where it connects to the condensor all the way thru to the contactor.

Please make sure power is off on the condensor when tracing.
 
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Old 12-16-17, 09:15 AM
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Good morning Pete. Thank you for your replies. Actually, I didn't measure the resistance from the yellow wire to the ground right last time. I was using the wrong scale 0-200. This morning I tried a different scale and it shows around 600 Ohm from the yellow wire to ground. That causes the fuse to blow I think. Could you give me some suggestions on what to look for next. Thank you very much and have a nice weekend.
 

Last edited by ryanbh; 12-16-17 at 09:59 AM.
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Old 12-16-17, 10:48 AM
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Could it be a bad defrost board? I have Goodman Parts PCBDM133S DEFROST CONTROL BOARD on my heat pump. Can I bypass the defrost board to get the compressor run to check if the board is bad?
 
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Old 12-16-17, 11:18 AM
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You're still not reading/setting the meter right. If it has multiple ohms scales you want Rx1.

Lets confirm something...... when you disconnect the yellow wire splice where it enters the condensor..... the short is gone. Is this correct ??

You should be able to follow that yellow wire from that splice thru the unit.... thru a pressure switch.... then to the defrost board or contactor. Have you followed this wire looking for shorts/abrasions to metal ?
 
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Old 12-16-17, 11:26 AM
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I have this multimeters Etekcity Msr-r500 Digital Multimeter. When I set it to 200 it showed 1 (or I). When I changed to 2000 it shows 624. I am not sure if I am doing it right.
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Regarding the yellow wire, yes, there is no problem if the yellow wire splice is disconnected. However, if I connect the yellow wire from thermostat, it blew fuse. I check it again today and see no visible damage on the yellow wire from home to contactor.
 

Last edited by PJmax; 12-16-17 at 11:58 AM. Reason: added labeled meter pic
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Old 12-16-17, 11:57 AM
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We are not on the same page here. You need to follow me a little closer.

There is a cable from the thermostat to the air handler.
Then another cable from the air handler to the condensor.

Connect the thermostat as 100% normal.
Open the yellow splice AT the air handler.
Set stat to heat and wait 15 minutes. Does the fuse blow ?

If no.... turn stat off. Reconnect yellow splice at air handler.
Open splice outside where it enters the condensor at the connection point.
Put stat in heat mode. Wait 15 minutes. Does fuse blow now ?

I pointed out the ohm scale you should be using. When you short the leads together it should show close to 0 ohms. Maybe 1 or 2 ohms. When the yellow wire is completely intact with all splices closed and all connections made... you should measure approx 15 ohms to ground or to a C connection.
 
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Old 12-16-17, 12:39 PM
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Pete, the electric heater runs fine when I disconnect either the yellow cable in the air handler or the yellow cable that go to the condenser. I guess that as long as there is no 24volt to the condenser, then there is no problem. Regarding the resistence on the yellow splice, there is no difference in the resistence between the one that is running and the one that blow fuses. They are the same blank (with an indicator 1 as it cannot measure) at RX1 scale (200 ohm) and 592 at 2000 Ohm scale when I put one of the lead to the connection and the other lead to ground. I also put one lead to the yellow splice and one lead to ground and see no continuity. Does it mean that there is no short ???
 
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Old 12-16-17, 01:17 PM
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It seems like you are saying that if the yellow wire is connected everywhere in the house but not at the condensor.... the fuse doesn't blow. That's good. That eliminates problems in the house and the house side of the circuit will show no continuity to ground.

So if you go back out to the air handler.... go to the defrost board and measure from the Y terminal to the C terminal. See what you get.

Then measure from that same C terminal to where the yellow wire from the house would connect at the wire nut splice point. (From condensor yellow to C) What do you measure there ?

I'm trying to remember if the defrost board interrupts the Y connection to the contactor.
 
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Old 12-16-17, 01:32 PM
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Do you mean measure the resistance or measure the voltage? Well, I will unplug the power and measure both resistence and voltage then.
 
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Old 12-16-17, 01:33 PM
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Continuity..... OHMS on 200 scale.
 
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Old 12-16-17, 01:37 PM
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Should I turn off all power to air handler and AC? or leave the handler on? Well, I will turn them all off first.
 
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Old 12-16-17, 01:39 PM
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When messing around with the thermostat wiring.... the air handler should be off. When messing around in the condensor.... the condensor power should be shut off.

Since you're measuring resistance.... both can be off.
 
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Old 12-16-17, 01:49 PM
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I measured the resistance from terminal Y to C and from C to the Y that goes from inside in 200 Ohm scale. In both cases the meter show blank (with indicator 1, i.e., it cant measure, I think).
 
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Old 12-16-17, 02:01 PM
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If you're ever measuring continuity (ohms) and you aren't sure if the meter is working.... just touch the leads together and it should show a short on the display..


What you've found would indicate an open..... no short.
Hmmmm..... not actually what I expected. The contactor coil is not being seen here.

If you're still going outside.... grab the model number for the condensor and using your meter.... measure at the contactor..... at the two small wires that go to the coil. Probably a yellow and maybe a brown, blue or black.
 
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Old 12-16-17, 02:26 PM
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The model number is GSZ130361BE . I measured resistance among all small wires around the contactor. Only the two wire that run from terminal C and CONT on the defrost board to two sides of the contactor as a nonblank reading which is 16.2 OHMs. Other pairs show blank or open, I guess.
 
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Old 12-16-17, 04:13 PM
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Ok..... so the Y signal is processed on that board. That reading is perfect and shows the actual contactor is ok, Let me look up the manual for that unit and see where to go.

At this point.... it may just be a problem defrost board.
 
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Old 12-16-17, 05:43 PM
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I ordered a defrost board already. If the current is still good, then I will have a spare one. Otherwise, I will definitely need it. If you found something to look for or have some idea to check the defrost board by multimeter, please let me know. Thank you very much for your help. I really appreciate your suggestions/time.
 
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Old 12-19-17, 01:06 PM
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Hi PJmax. I took the defrost board out today and found out that it was burned. I put the new one in and fuse still blew. I measure the voltage on transformer in the air handler and see 27 vol. Is this normal or the transformer is bad already?
Thank you.
 
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Old 12-19-17, 02:28 PM
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27v measured on a 24vac circuit is fine.

You're going to need to check every low voltage terminal on the defrost board to ground. Something is shorted out there.
 
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Old 12-19-17, 02:36 PM
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There is a resistance from C and Crv terminal on the defrost board to ground. Is this a short here?
 
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Old 12-19-17, 03:39 PM
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Yes.... C (common) and Crv (common reversing valve) should show 0 ohms.
Close to a dead short.
 
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Old 12-20-17, 02:27 PM
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Yes, it shows 0 Ohm. What I meant is there is some resistance from C to ground.
Also, the resistor on the defrost board from PS2 to C got burnt. Does this have something to do with a short to ground or blowing fuse? Thank you.
 
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Old 12-20-17, 04:24 PM
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It doesn't have to show 0 ohms to be short. 1, 2, 3, 4 ohms are all close to a short. Your meter could be an ohm or two off.

I really can't tell you much about shorted parts on the board. If that is the new board.... a burned resistor doesn't sound good.

Did you find any other low resistances ? You should have.
The contactor..... possibly Y..... should be around 15 ohms.
The reversing valve should be also higher than 15 ohms...... and probably nearer to 50 ohms.
Anything under 5 ohms is suspect.
 
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Old 12-21-17, 11:40 AM
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Should there be some resistance from the DFT terminal (or the red wire connected to this terminal) to the ground?
 
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Old 12-21-17, 11:57 AM
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Hi PJmax, I tested two units and one of them showed DFT to ground around 15 Ohms and the other showed DFT to ground open. Could you give me some suggestion here. Thanks.
 
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Old 12-24-17, 02:43 PM
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Any one can help me? Does any one know the range for the resistance of a heat sequencer 2 switches? I measured mine and get around 160 Ohms so I am not sure if it is still good. (The other working unit in my place has a heat sequence 1 switch with resistance about 60 Ohms only). They are not the same type so I cannot conclude anything. Thanks for any tips.
 
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Old 12-24-17, 03:48 PM
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It's been an incredibly busy time of year.

I thought we had the electric heat by itself working ok and the short was when the compressor (Y) line was activated. The electric heat can be activated directly from the thermostat or from the defrost board. Since it's ok from the thermostat.... I don't think there is an issue there.

15 ohms sounds like the defrost valve or contactor.

I need to look up that defrost board. I'll be back shortly.
 
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Old 12-24-17, 06:16 PM
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There are two differences between the working unit and the dead unit.

1. In the dead unit, the defrost temperature sensor has no resistance from DFT to ground while the working one has.
So I am not sure if my problem is a faulty defrost temperature sensor.
2. The resistance of the white wire to common in the dead unit is very high 180 Ohms (vs 60 Ohm from white wire to common in the working unit). I found out that this is a consequence of the resistance on both side of heat sequencer on both units. The resistance of the heat sequencer of working unit is around 60 Ohms while the resistance of the heat sequencer of the dead unit is around 180 Ohms. However, the dead unit uses a 2 switches heat sequencer while the working one uses 1 switch heat sequencer only. Therefore, I need to figure out the range of resistance for a 2 switch heat sequencer. I read somewhere on the internet that bad heat sequencer can cause the unit run on both heat pump and electric heat that could blow up fuses. Thus, I need to make sure if my heat sequencer is good first before checking the defrost temperature sensor.

Thanks for your help and Merry Christmas.
 
 

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