Sunday, January 26, 2014

Amana and Goodman Downflow Furnace Control Board Fix.

Unless you are a competent service technician, I would not attempt this procedure at all. However, you may be able if you are a homeowner to clue in the clueless in case your tech is having trouble figuring this out. God forbid he or she is, but it will help nevertheless. As always, I have zero control over the quality of your work. Using tools and working around electrical always has some risk of death, injury, or property damage. Improper service methods can damage expensive parts and compromise the safety and integrity of the equipment you are working on. Make sure you shut off the breaker or switch at the handybox before working on any equipment.
Amana, which is now owned by Daikin, still shares many mechanical and electrical components with Goodman, save that Amana has a stainless steel heat exchanger. Their products are screwed together pretty well, and the materials are decent, but even they can make a mistake once in a while. This one affects their downflow furnaces with the green cabinet made through the late 2000's and possibly beyond. The vintage of this unit is 2008 and like many of these units, they are plagued with intermittent operation that can confound the most seasoned of services techs. Eventually, this furnace will flat out not operate, requiring lots of troubleshooting when it is least convenient.
Usually this is one in the morning with 0 degrees Fahrenheit with -20 wind chills. The problem starts in this case from the factory with the placement of the control board. It's placed on a panel covering the heat exchanger and with time, this heat will damage the board.  You'll need a new board, a 1/8 drill bit and a drill motor, needlenose pliers, a screwdriver and a marker with a fine point.
This is the original board in the factory spot. Note the discoloring cater corner from the main wiring harness.

Here it is from the back. This is damaged.

You need to remove the old board by squeezing the standoff clips holding it to the panel and gently lifting it up. Since the new board doesn't have any clips included, you will need to reuse the old ones. Using your pliers and a screwdriver, carefully pull the clips from their holes at an angle to avoid breaking them. Use the screwdriver to gently pry as you pull them. Put the clips into same box as the new board. If you want to remove all the wires first, you can use the old board as a template to drill four holes into the side of the cabinet to mount the new board. If not, carefully use the new board as one. Make sure that you locate it away from any screws as pictured above and all the wiring must be able to reach the board in its new position. You may need to position the board on the outside of the cabinet to make your marks where the inducer will get in the way of your drill. Carefully drill holes from the outside of the cabinet without hitting anything inside. Once you drill the holes, install the standoff clips to the new board as pictured below.

Transfer each connection from the old to the new board. If you mounted the new board correctly, you can hook these up easily; you may have to remove a zip tie or two to get the wires where you need them.

Tie any wires back that could be resting against hot or moving parts including where the old board was mounted at the factory. This was given to me from Goodman's tech support 4 years ago. I've been using it ever since, even on furnaces that haven't had symptoms yet. Another hint: if the furnace won't come on, but if you gently push in the center of the board and it works for a moment replace the board. When you're satisfied everything's connected, turn on the power to the unit, set the thermostat and cycle it to make sure it doesn't need any more work done to it. Thank the customer for the work, hand him or her the invoice and you're done. The customer will be amazed at your skills. Maranatha! :)


Unknown said...

Just order my replacement board. Nice write-up on repair. Problem is exactly what I am seeing. If i gently press on wires on main harness during gas valve actuation, the furnace comes back to life. I also saw a small arcing reflecting off cabinet behind the board which clued me in as a board issue rather than wiring.

I am going to try relocating as you suggested, so hopefully I won't be swapping boards every few years, as I see other reviewers on amazon are doing.

My Goodman is model GDS81155CXBB

Thanks again for sharing your knowledge.


Victoria Martinez said...

These are some of the very effective tips given for a better HVAC system. And the maintenance guide is distinguish and useful. Heating and Cooling Milton

Walter Grace said...

Thank you