My goodman heat pump is acting up and blowing 3 amp fuses after it runs for about 3-5 minutes. I have measured y to ground at the condenser and it is an open, and i have measured C to ground at the condenser and its a short- about 4 ohms. The contactor measures 15 ohms. I have no HVAC background but have solid electronics and troubleshooting background. Any help would be amazing!

 

This is the board in the condenser, that hotspot near those resistors doesn't look very promising...

 

Welcome to the forums.

The C wire may show a short to ground. That would be normal in many systems.
If your contactor coil measures 15 ohms then you should have 15 ohms between yellow (Y) and C.

Since you have a heat pump...... is the fuse blowing when it goes into defrost ?
If it blows during defrost.... it's a shorting reversing valve line.

If it's in heat mode.... check for a short from R to ground, Y to ground.
Visually inspect the outside cable as it usually gets chewed up and causes that problem.

 

That's the defrost control board. Looks fairly normal including those resistors.

 

PJmax,
I don't know if its blowing in defrost or heat mode, It just blows when i turn on my heat after about 3-5 minutes of running.

 

Oh and i forgot to add the system is only about 2.5 year old. The air handler and the heat hump.

 

And how do i check my reversing valve line?

 

Do you know if your thermostat has a compressor delay ? Most do.
That means the compressor doesn't start for 3-5 minutes on a demand for cooling or heating.

If you set it to heat and nothing happens outside and then the compressor just starts and blows the fuse or it never starts...... check the yellow contactor wire.

 

R to Gr is an open
Y to Gr is quick 50-100 ohm flash then open.. tried it several times and it did it every time but different resistances but always very quickly went to an open
Y to C is an open

I am pretty sure my unit has a delay.

 

The reversing valve is controlled by the O/B terminal of the stat usually on the orange wire. In A/C mode there is 24v on the orange line. There is 0v on the orange line during heat.

When the system is in heating mode and goes into defrost..... the defrost board activates the reversing valve so that the system is running in A/C mode. Takes the warm air from your house to deice the outside condenser.

You have delay...... so on a call for heat does the compressor run at all or does it just blow a fuse ?

 

I don't know. After i replaced the fuse the second time i hadn't crawled back into the attic again to replace and try. Its getting late and cold here. Luckily i have a fire place and am circulating warm air. I will replace the fuse first thing in the AM and see if the compressor kicks on at all and report back. Thank you for your help with this. and than you for being patient my lack of knowledge.

 

Here are my results:

Replaced 3amp fuse

Ran just the fan with no heat or AC for 15 minutes no issues

Have been running Heat for the last 15 minutes with no issues. Old lady says she feels like its warmer than before in this season..

Of note:
1. My thermostat said AUX Heat when it first turned on and then that went out and it says heat on
2. There was no compressor delay. As soon as I turned on the heat, the condenser immediately kicked on.
3. There were also some spiders and bugs in the condenser electrical area that I blew out with compressed air. I don't think it was a enough to make a difference. There was a small spider web behind the defrost board.

I hate troubleshooting ghost faults. I wish something was just burned up so I could replace it. Do you think that there might be a cracked wire somewhere and me messing around unshorted or removed the ground from a wire? Or maybe something else. We get a lot of brown outs/power losses here in the country and i wasn't home when the initial blown fuse happened so its hard to say if it was involved. Just kind at a loss right now. Its relatively warm outside (mid to low twenties at night and mid 40's during the day) and I don't want the problem to come back when its 20 degrees during the day. Any ideas?

 

Ok so here is another update. No sooner than i posted that reply the fuse blew again. it ran for almost exactly 30 minutes and shut down. Taking all recommendations on what to do next.

 

Since it took that long and ambient didn't change much I'd check wiring inside the condenser. It would be good to know if the unit had just shifted into defrost. Do you know when that happens ? It should be easy to hear if you can hear the compressor inside.

This video is just to show you what and where the rev valve is. The wiring that connects the valve to the defrost board can be run near something sharp and short out. Since it's only live in A/C mode or defrost mode... is the reason I keep mentioning defrost. It's possible to have a bad contactor but it doesn't usually take that long to short.
Goodman reversing valve video

It is possible to have a shorting problem that just can't be found. I carry and install fuse holders and fuses. I use 2A fuses. I'll put one on the yellow(Y) compressor, and the red (R) 24v and the white (W) reheat strip wires. Then I'll wait for one particular fuse to blow and then diagnose from there.

 

it didn't make any different noises when it stopped. It just stopped. and let out a hissing noise. I noticed a lot of condensation on the copper piping inside the condenser not sure if that is relevant. When it stopped everything just stopped all at once too. Air handler in the attic and the condenser. Feel like I chasing my tail here. So I should ohm out the wires in the eletrcial area or inside the condenser itself?

 

I also pulled Crv and Orv and measured across the solenoid and it measured 13 ohms. Shouldn't that be more like 100 ohms or more? Could that indicated a bad reversing valve solenoid and possibly a bad reversing valve?

 

Current plan is to remove Crv and Orv and tape then off and run the system for an hour to see if it the fuse blows. If it runs for an hour or more i would start to think its the solenoid or RV...

 

latest up date.. fuse blew after 45 minutes with Crv and Orv removed from circuit board.

 

A quick fix gamble is to replace round electrolytic capacitor C-2 in circle at center of circuit board. Electrolytic s have shortest life.

While it is best to remove cap for testing, for a $1.00 part just replace it.

In upper right of picture near diode D2 and resistors R21 and R23 there appear to be some fuzz and discoloration. Would clean that area.

 

I just might replace the whole board because i am at a loss.. talk to about 4 HVAC repair people and they all don't know where to turn next.....

 

I'm an analyst. I won't replace a board unless I know it's bad.

Put a 2A fuse on the Y line at the condenser.
Put a 2A fuse on the R line at the condenser.
If the R fuse blows...... replace the board.

 

Without going through a lot of trouble shooting, causes of many problems due to printed circuit boards can be found with closed visual inspection. Fix is often just bad connection or debris on boards.On this tread DH Post #19 pointed out possible visual issues observed in Post #2 picture.

Here is typical good example of visual inspection saving time and money. See Doughess Post #1

https://www.doityourself.com/forum/a...ml#post2853722

 

*** Sorry, this was accidental duplication of prior post************

This reminds me of when wife comes in to kitchen and asks why her car will not start.

I ask if it still has battery? Does it still have engine?

Am not into head games. Tell her I will have to look at it.

 

OK my intention is to make some fusable jumpers with some supplies i have and some stuff i pick up on the way home. along with some more 3amp and 2amp fuses.....

I will also blow off the circuit card a little more thoroughly and clean it up before my next trail run. If the R wire blows its the card.. so... if the Y wire blows... whats next?

 

Made some fused splices... putting in Y and R.. wish me luck

 

Brushed off the defrost board with a clean soft bristle nylon paint brush, sprayed down the defrost board, front and back, with contact cleaner, and installed fuse jumpers on R and Y. Been running for 15 minutes no issues, Seems like every time I post a reply it goes down, so here goes nothing! Crossing my fingers it either fixes it or at least gives me a new indication to check out.

 

One hour ten minutes.. still running strong....

 

OK its been running for a solid two hours with no issues....going to go button it all back together and see what happens

 

While working...... keep an eye open for anywhere a wire can be cut/nicked by a sharp edge.
I can't tell you how many times I've found the cable from the house to the condenser nicked or cut.
A hungry animal or a wayward weedeater.

 

Thanks PJmax! I had looked at the wire earlier and it looked ok but i definitely check it again.. Thanks again for all your time, assistance and patience! It is greatly appreciated and I am very grateful. I also now have a new tool for the tool box with the fuse jumpers. kind of neat addition. I think i am going to upgrade them to circuit breakers just for the coolness factor.

 

Well it cycled on and off all night as it should... Thanks again for the help!

 

Post #2 Had photo of board but is now string of garbled data.

That photo is key to understanding issues here.

Someone please restore it.

 

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