Hi!

Our Goodman gas furnace GDS80703AXBC has an intermittent issue with not running properly and it gives 4 red flashes / open high limit error on the control board. It started when the furnace was running last week and we had a split second power outage - enough to reset clocks on all of the appliances in our house.

Symptoms
When the furnace is called for heat by our thermostat, then immediately the 4 flashes start and nothing else happens. Fans are on during this time the main fan remains on after blower turns off.

Troubleshooting steps I have taken so far:
1) Checked the primary limit switch. Appears to work. When I got the furnace to work then the switch received and passed 24 volts properly. When the control board started flashing then no voltage was going into the primary limit switch.
2) I normally replace the furnace filter every 6 weeks. When I removed the filter then it did not change the status with 4 flashes on the control board.
3) When I fiddled with the wiring up top (not necessarily the wires going into the board but rather the 15 pin wires into the furnace then I was able to get it to run last time. I also tried fiddling with the wires on the board too.
4) The furnace is approximately 13 years old. First several years it worked a lot with probably minimal/no maintenance as that was prior to us buying the house.
5) We live in Utah. Home is older style masonry same level property.
6) I have not done my annual maintenance on the furnace yet this year (clean burners, flame sensor and vacuum around the furnace. I am happy to listen to tips on how to do a better annual "furnace tune-up" if there are good resources)

Additional detail but probably not relevant..
2 years ago I seemed to have an intermittent issue with the furnace wiring (same 15 pin wire)- when I fiddled with it then furnace started working again. I called a tech out back then and they just cleaned the burners and the furnace and said there is nothing wrong with the wiring. Not sure if that is true or not.

Around the same time 2 years back I was advised to run an additional ground wire after some troubleshooting with voltage meter on video chat. The ground runs from the burner ground to the metal next to the switch. This is when I had another issue with the board blinking multiple times indicating that the gas valve was bad. The ground seemed to fix the issue and it has not come up again.

In summary
Interestingly when we had to original power outage last week then the furnace stopped working. I fiddled with the primary limit switch and got it to work without issues again. Then days warmed up a bit and we did not use the furnace for a couple of days. Today we had another (planned) power outage by the city and we had the same issue with the furnace. We have a young baby at the house and I would like to make sure I get this issue addressed as soon as possible. I suspect the issue is the control board and I found a new control board on supplyhouse.com that I could have delivered by Wednesday. Currently the furnace has run fine twice back to back.

Thank you for the help in advance.

 

Welcome to the forums.

A bit much to read.
Is the limit switch intermittent or not ? If it is..... change it.
It should not be opening until it gets hot.

Typically the contacts get corroded from the switch constantly cycling.

 

Thank you.

I figured that I should include as much info in the post as possible, sorry if it came out too long.

The switch seems fine to me. I tested for voltage and any time there is incoming voltage then the limit switch correctly passes the voltage onwards (switch is closed). The problem is that sometimes there is no incoming voltage from the control board and the board throws an error code high limit open which is not the true. The high limit primary switch is closed. I verified with resistance as well when I took out the unit.

I think that the motherboard might be faulty. Alternatively some bad wiring can be the culprit but I am not sure how to exactly move forward. After fiddling with wires it randomly started working again.

 

That is a common problem. Get some contact cleaner. Not WD40. Pull the plug out of the board. Spray the pins on the plug. Shake gently and then plug back in. Pull out and plug in several times will clean the steel contacts.

Don't spray the control board.

 

Thank you. I received my contact cleaner from Amazon and after spraying the contacts I had no issues for .. a few days.

Now my gas valve is not opening even after receiving 27 volts. Does this mean my gas valve needs a replacement or is there a chance that something else is an issue?

Basically there is a call for heat and igniter becomes red but gas is not flowing. After checking with multimeter I see 27 volts applied to gas valve but the gas valve does not open gas flow.

 

Where are you checking for power to the valve..... right at the valve ?
If yes.... do the same thing with the cleaner.
Hit the gas valve plug, reinstall and remove several times.

If this doesn't seem to help..... start the call for heat..... after the igniter warms up and you hear the relay click in the controller for the gas valve.... wiggle the plug on the gas valve and see if that helps. You only have a few seconds to try that.

 

I tried and there were no clicks in the gas valve. Still same issue.

I ended up getting a contractor to come out and replace the gas valve. He agreed the valve was bad. Because of the prior intermittent issue with the main board then the board also needs to be replaced and seems like it got damaged with the power issues to the house we had a week earlier. The contractor was very reasonable.

I opted to order a new board that I placed an order myself (+ several other backup parts for the furnace) from supplyhouse.com. I plan on installing the board myself on Thursday evening once i get the parts. I chose to get several other parts too such as limit switch, transformer, new wiring etc to keep on hand in case something goes bad plus the cost of these parts is fairly inexpensive (~$70) vs having to buy something in a rush.