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Turn ALL breakers to furnace OFF. Go to the Fan Switch and jumper across it. Turn breakers back on and set switches for Fan to run.

Did it run ?


Then, make sure all breakers are on and switches are on Heat and Auto.

Set t-stat to LOWEST temp setting, this should be enough to NOT get call for Heat.

Place meter leads across the 2 wire connections at t-stat, red lead on red and black lead on white. Your wire colors may vary.

Test for 24-28vac.

Let me know what you get.


There is another transformer in there somewhere, it should be in the upper box. What is that behind the bundle of wires to the left ?

It MAY be in outside Condenser Unit , but it is somewhere and will be 30 or 40VA.

This is sounding like a t-stat reversing relay or system switch failure.


Thanks,
Robert

in the upper box behind the wires is the speed selector board. There is no transformer in the condensor unit, either.

fan came on when jumpered, getting 28 v at t-stat.

Ok, maybe it's been doused in casper mist, but there is a 30 or 40VA transformer somewhere for you to have a/c.

Does the upper box have a model or part number on the front, bottom, sides or back of cover or inside wall of box ?

Leave fan switch jumpered and set control box switches to Cool and Auto.

Set t-stat temp lever at 65* and if your t-stat has a mode switch, set it to Heat.

Tell me what comes o n or doesn't inside and out.

Keep looking for the elusive transformer.

What tonnage is your a/c ? If not known, can you tell me the condenser or inside a-coil model numers ?


Robert

left the fan switch jumpered, turned to cool and auto. Fan is running and A/c unit is running , blowing super cool air also.

Fan switch is bad then?

Hi,

Yep, appears that way. Does it have a p/n on it ?

Did you check the control box for a p/n or model number ?

How many terminals and does it have a rocker switch on front ?


Thanks,
Robert