New thermostat, 4 wire?

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  #1  
Old 09-26-09, 03:31 PM
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New thermostat, 4 wire?

I am installing a Venstar Thermostat replacing an old 1993 thermostat controlling a heat pump. I have basically 4 wires coming down and the old thermostat had this configuration:


Red wire <--> Rc
White wire <--> O
Green wire <--> G
Yellow wire <--> Y and W
Blue wire (capped)

On the new thermostat, there are only instructions for 6 wire...




What am I missing? I am not sure how to wire. Any help would be appreciated.

Thanks.
 

Last edited by Jay11J; 09-27-09 at 02:16 PM. Reason: making page easier to read. (Removed photo)
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Old 09-26-09, 07:42 PM
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Old---------New
Rc----Red---R
O----White---O
G----Green---G
Y----Yellow---Y

make sure set the jumper. not sure, let me know.

What is your back up heat? (See it not hooked up on the old t-stat)
 
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Old 09-26-09, 10:20 PM
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Thanks Jay for such a quick response. I wish it was that easy :-) I tried that and the thermostat wont power on at all. I have two units so I tried both thermostats I bought on this to make sure it wasn't a bad unit.

I have installed other thermostats and this one was odd to me since the yellow wire went to 'Y' and to 'W'. Also, I can't tell if Rc and Rh may be jumpered on the old thermostat?

I have the jumpers set to ELEC (FAN), HP (I assume Heat Pump), and I tried both O and B.

The new installation guide is here.

As far as the back up heat, I have never heard of it. I am in Phoenix so maybe we don't need it? :-)
 
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Old 09-26-09, 10:46 PM
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What happens when you touch R and G wire?

Give me the make and model # of the air handler/furnace.
 
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Old 09-27-09, 09:30 AM
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Thanks for your help Jay.

I have two units...

Carrier FA4ANF042 and FA4ANF036. Both of the old thermostats are wired the same.

I tested jumping R and G and the fan does come on.
 
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Old 09-27-09, 02:13 PM
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We know the unit has power, did you hook up C or use battery?
 
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Old 09-27-09, 02:43 PM
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I don't see that these thermostats have batteries... I tried connecting the capped blue wire to C on the thermostat with no luck. Do I need to jumper the R to somewhere else to power?

Thanks for your help.
 
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Old 09-27-09, 08:07 PM
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Was the blue hooked up to C at the furnace?
 
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Old 09-27-09, 10:45 PM
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Unfortunately, I am not the person crawling around the attic hooking up wires my unit so I may have to bring someone in to install these for me. I thought it would be a simple change over but it looks like more of a major move. :-(
 
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Old 09-28-09, 06:07 AM
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The manual isn't clear about saying if C has to be hooked up or not.. But it does show it hooked up, so that kinda tells me you have to get C wired up to light up the display.
 
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