Goodman Furnace/AC Unit Mod#-PGB036075

[KennyB221]

My AC wasn't working - no fan, nothing, so I took a look at the control panel on the unit and checked to make sure i had power where it was supposed to go. Everything looked fine, so I checked out the circuit board and pulled the 5amp fuse out - blown! Great, so I replaced it and KABLOOEY! blown again. Then I did a really STUPID thing! I put a 15amp fuse in and the circuit board started to smoke :shock:. Little bubbles appeared on the chips. And still, Yes no cooling.

Can y'all help?

[RegUS_PatOff]

SearsParts shows a few similar(?) models

http://www.searspartsdirect.com/partsdirect/retrieveModelAction!retrieve.action?modelNumber=PGB036

 

[KennyB221]

I'm really just trying to diagnose the problem - do i need a new board? is that what the problem was? Or is there something else I should do?

Thanks

[RegUS_PatOff]

I was just helping to find some parts diagrams, ect..

I don't know what the fuse is for or what would make it blow.

Maybe someone else here would know.

[Cactus Bob]

first you will need a board . THEN SWITCH TO A 3 AMP FUSE FOR TESTING !(buy a box from a auto supply store )   next . do you have a split system ?( a furnance or air handler and then another unit on the ground outside somewhere )  or do you have a package unit ( one box on roof or on ground that has everthing in it )  ?     now that the boardis toast  ..... you will need the board first ...installed but not powered up ...... do that and get back to us  i can talk you through the check out /fix  ........ON SECOND THOUGHT : how do you know the board burned up , these boards are coated with a clear paint the after a while yellows and looks burned and bubbled but the board is fine , so if you did not see with you own eyes a part smoke it might not be bad ..... can you poast a photo of the board , front and back ? ...be carefull removeing it from the little plastic stands its mounted with , do not break them ..... good luck

[KennyB221]

Hey Guys!

Yes, its a package unit - everything in one outside unit. I'm pretty sure the board is fried - I SAW the bubbles appearing on the surface of the chips and the smoke coming from behind them. Any ideas where I can get a new board?

Thanks:shock:

[KennyB221]

I'll post a photo soonest.

Ken

[dkpd1581]

Generally speaking Johnstone Supply is a Goodman dealer; however, they most likely will not sell to you the home owner.  You can try some internet sites via a Google search and see what is available.

Most likely your fuse blew due to a short to ground somewhere in the low volt wiring.  You can check to see if the board is still salvagable.  Find the low voltage terminal board inside the control section and write down what control wire goes to which terminal on the board.  With power off, remove each and every t-stat control wire from the low volt terminal board and pull them aside.  Replace the 3 amp fuse in the board and then turn on the disconnect.

Measure from R to C and you should register between 24-27 VAC.  If you do not, check the windings for continuity on both sides of the transformer (obviously with the disconnect turned back off).  Typically a transformer will fail by opening on the high voltage side windings; however, it is possible for the low volt side to open.  Just check continuity through both.  Replace the transformer if necessary - be sure to get at least the VA rating of the one in there now.  You can go up in VA rating just not down.

If you have 24VAC between R and C then use a jumper wire with aligator clips (and preferably with a resetable fuse link in line) by attaching one clip to the R (+24VAC)  and then touch the other end to G (fan terminal).  If the indoor blower starts up, then the fan circuit is good.  Leave one side attached to R and then touch the other to W (heat circuit assuming a non-heat pump unit).  The inducer should spin up and within 45 seconds the gas valve should pull and start the burners.  Leave the R attached and then touch the Y (cooling terminal).  The compressor and outdoor fan should start up.  There may be a 5 minute time delay on the board  to prevent short cycling on a loss of power - remember we have turned the disconnect on and off a few times by now.  That is why we did the Y terminal test last - to help burn up some of that time delay possibly on the board.  If it does not start immediately, leave it attached to the Y and check you watch 5 minutes later and see if you have a start up.

If the unit has responded so far (again assuming non-heat pump) then the board is still good.  If it has not responded to any one of these tests R-G, R-W, R-Y, or the 3 amp fuse on the board blows at any time during this, then the board is bad and must be replaced.

In the event you replace the board for whatever reason, you still will have some  low volt short or defect in the system.  This could be a direct short to ground in the t-stat control wiring, a short to ground through one of the safety switches (High pressure/low pressure, frost stat -typically where a wire has vibrated and abraded the wire insulation, or even a stuck or defective coil on a contactor).  The purpose of removing the t-stat wire earlier is to "half the problem" - is the problem at the unit or at the t-stat.  If it is not at the unit, then we "half the problem" again by dividing the wiring and the t-stat itself.  That will determine if we replace some 18/8 control wiring or the t-stat.  Then off we go from there.  Halfing a problem will generally bring you right to the source very quickly.

Grab your meter, see if the board is even still good.  If it is then do the tests described.  If not, replace the board and before reattaching wiring to the low volt terminal board test the t-stat wiring itself, t-stat itself, and the 24VAC safety circuit at the package unit.  Let us know and we will go from there.