[dennismc]

Hello all,

I have two carrier sta58155-20 furnaces running in twin mode, single duct, one thermostat.

I had power issues and attempted to run one off a generator before I knew they were wired together. Short story, LH furnace ran for 10 mins then shut down, no error code light at all now.

Power issues fixed, now no light on LH furnace, RH has steady ready light. But no go.

First question, woudl the board have blown in the LH one or a relay or switch?

Second ?, could I swap the board out of the RH, place in LH and run only one furnace for now while waiting for replacement part? Or would this require disconnecting the Twining from them>?

Thank you

Dennis

 

[beenthere]

May have a blown low voltage fuse, or the transformer may have gone out. If the duct system is twinned. Then running just one furnace ill cause it to over heat.

 

[dennismc]

Thank you.

Will test the transformer today, any idea where the low voltage fuse might be to check?

 

[Marty S.]

Low voltage fuse looks like a car fuse and it's located on the control board. There's going to be a limit switch behind the blower. Odds are the second furnace blower motor was spinning backwards and the heat from the other furnace tripped that limit.

 

[dennismc]

Ok 3amp fuse on the board is good.

The RH furnace didnt have any power to it when I hooked up to the generator. Didnt realize they were twinned and both had to run. So when I had it hooked to the generator, only one furnace, as it turns out was the LH main one had power to run.


ANy other switches I should check?

 

[beenthere]

Check if the low voltage transformer is getting 120 volt, and if its out putting 24 volts.

Also make sure there is no emergency swith at the top of the basement steps that got turned off accidentally.