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athomas387 03-10-2008 07:31 PM

Thermostat Help
My electrician father-in-law installed a 7400D during the fall. I am certain that something in the installation popped the fuse on the control board, once the fuse was replaced the AC did work however, the heat has not worked since (perhaps the fuse was broken before he started). I am at a loss for where to go now. All six wires are currently marked (for what thats worth). But only connected to 5 of the terminals

When I look at the T-stat it is configured as such.
C=Nothing Connected
W2=Nothing Connected

1)Does the side of the terminal block used affect the operation of the furnace?
2)Should I be moving the wires to the heat pump side. We have a Rheem 10 Seer Heat pump. We are using a RTH7400D now and it was a Rodgers White 80 series (I'm pretty sure).

In the Furnace the wires are configured as follows.
C=1 red & 1 tan
R=1 red
W=2 white & 1 green
G=1 Green
Y=2 Yellow
The furnace is a Rheem RGPH-07EAUER, with fully functioning AC, there never appears to be any as flow or ignition attempt when T-stat is set for heat. The IFC has the green PWR & OK LED's on.
I'd appreciate any assistance I could get, even if its just advice to throw in the towel and let someone rewire the whole system.


athomas387 03-10-2008 07:50 PM

I keep thinking that G,Y &R must be correct as the AC is working well. But E, X1 & B are suspect. But my opinion and knowledge is suspect too!


biggles 03-10-2008 09:22 PM

remove all the wires off the subbase and stat over.....the LETTER on the terminal strip in the furnace is thr LANDING point for the same wire into the need R,C,G,Y1,W1...jump R to RH on thr subbase that is for AUTO on the syatems switch if you have that option.note the color of the wires coming off the furnace terminal board and LETTER and land only those off stat board going up stairs.if you have W2 off the furnace board connect it to W2 on the subbase your hookup as is is for heatpumps and such...might be shorting the fuse when it all your connecting with the furnace switch off on the breaker or at the furnace.:whistling2:

athomas387 03-10-2008 10:06 PM

Ok, then what happens to the E & X1 which were not represented on the IFC?
Currently there are only connections on the conventional side G,Y,W & R.


End Grain 03-11-2008 12:24 AM

Does the thermostat have a DIP switch or a jumper for the type of furnace, i.e. GAS or ELECTRIC?? If yes, is it configured correctly?

athomas387 03-11-2008 01:51 AM

Not dip switch or jumpered but manual intervention with the menu screen of the thermostat. Its menu driven once you get into the programming level. It is currrently set as gas furnace/heat pump

biggles 03-11-2008 05:54 AM

if it isn't coming off the furnace terminals it won't get connected up to the stat! with the stat off the base and looking at the subbase head on R to G...FAN R to Y1...COOL R to W1...HEAT if you jump R to any of those 3 that should be what runs.NOTE...just bump R/Y1 for a condenser quick check..don't run it long needs G for FAN.

athomas387 03-11-2008 10:07 AM

Wasnt quite ready to rewire the T-stat, without proving each individual wire from both the T-stat and furnace.
End Grain,
However I did go back and step throough each stage of the config, to ensure they are correct. Didn't change any of them but afterwards the furnace kicked on. Go figure

End Grain 03-11-2008 10:57 AM


Originally Posted by athomas387 (Post 106587)
..... I did go back and step throough each stage of the config, to ensure they are correct. Didn't change any of them but afterwards the furnace kicked on. Go figure

Athomas387, you owe the Thermostat Fairy big time for that one. :laughing:

athomas387 04-11-2008 03:22 PM

Looks like I really got trouble now. the furnace ran for a few days with no problem. Then it warmed up by mid month, Warm enough for the AC to come on AC ran for a few days, then nothing. I am going down to have a look now cuz it 80 degress in the the house today, hoping for a blown fuse. But'Ill bet the control board is dead though.

Any thoughts,
I still think the T-sat is wired wrong, one of presentation off the board is sharing a connection on the T- stat. will look to make sure which one while I 'm down there.

In my next post I'll have the connection details on the T-stat.


athomas387 04-11-2008 03:28 PM

Ahh I just remembered the pilot has never come back on, it was heating just offf the heat pump. Never saw pilot on when I parked in the garage, sounds like biggles is right rewiring the Tstat is in order

athomas387 04-11-2008 05:49 PM

Looks like the IFC died, I have checked the fuse, it looks good and the circuit breaker is not tripped. But there are no lights on, on the IFC.

Isn't the purpose of the in-line fuse to protect the IFC?
Will swap the fuse, for good measure, and check if i have a spare breaker to swap with.

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