Thermostat T5 display off and furnace blower runs randomly.

[jay surfs]

Honeywell Lyric T5 thermostat display went dark and turned off, disconnected from the app. I turned the furnace power on/off a few times and the thermostat display turned on for a min, then off.
I have a Goodman furnace GMES960805CU, 96%. The green LED light is steady on. The blower will randomly turn on and stay on for awhile, if I unplug the thermostat the blower turns off. Plug the therm back in and the display is still off but the blower will randomly turn on, no heat.

Any ideas whats going on here?

 

[Fitter30]

Thermostat needs the 24 vac for the display. Need to check for 24 vac at thermostat between R and C.
Touching R to W will bring on the heat. If there's power check that wires are tight at their terminals if they are stat is bad.

 

[Sponsor]

 

[jay surfs]

Thanks. first thing I did was install a new thermostat and of course that didnt fix it.

I tested it and Im not getting 24v. I also checked inside the furnace and not 24 there either. I am getting 120v coming into the unit (checked just to be sure).
I replaced the transformer and that didnt fix it so put the original back in.
The fuse is good on the motherboard.
Any other idears?
I have a pro coming out on Mon but thought I would continue to troubleshoot in case I can fog it out.

 

[WorthFlorida]

Is the furnace working at all? If not check the Interlack door Switch. when the cover is off it kills the power for safety. A few years ago a member posted a similar problem. He door switch went bad or out of adjustment. The manual has the wiring diagram. Here is the URL. Look at the bottom middle.

Goodman 0130M00243 Interlock Door Switch (0) List: $5.25 / ea $3.95 / ea In Stock ✔

Wiring Diagrams - Goodman MES96 U Series Service And Troubleshooting [Page 28]

Goodman MES96 U Series Manual Online: Wiring Diagrams. 6 FLASHES Wiring is subject to change. Always refer to the wiring diagram on the unit for the most up-to-date wiring. 28 AUTO RESET BAFFLE LIMIT YL BK BK NEUTRAL LINE MOTOR XFMR HUM EAC FLAME WH WH BK RD BK GN RD OR GY AUXILIARY...

www.manualslib.com

How are you checking voltage? Is there 120v on the primary? If yes then there is 24v on the output especially if it is new. Don't go any further until 24v ac is at the furnace.

The check voltage by place the voltmeter leads on both wires of the transformer, first the primary, then the secondary. If there is no voltage on the primary you need to back trace it.

 

[Fitter30]

There is a auto reset temp control burner ( might be a roll out switch)that feeds R from transformer has a red and orange wires on it. Feeds everything with 24 vac