Wire ac condenser to furnace Help

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Old 07-24-19, 07:13 AM
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Wire ac condenser to furnace Help

Hello So this is what I was left with I am trying to tie in fan on/off and a AC condenser I have 2 wires for my limit switch, 2 wires from my 24ac transformer, 2 wires from my AC condenser and 2 from my gas/heat and then a 5 wire to my thermostat There is no control board at all How would I go about wiring this and getting the AC and fan control on/off working
i am a low voltage security tech by trade so I do have some wiring knowledge I just did t want to jump into this without any insight

Thank You in Advance Scott
 
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Old 07-24-19, 12:12 PM
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If you have modern electronic thermostat use the wiring diagram for it. A typical heating/cooling thermostat wiring diagram shows how things are connected.

There are common terminal designations i.e. RH - heating on power, W - heat on, RC -cooling power, Y- cooling on, G -fan , C -transformer common.

If there is only one transformer then RC and RH are jumpered and connected to it.

Here is typical wiring Figure 5 on page 3: https://s3.amazonaws.com/s3.supplyho...structions.pdf
 
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Old 07-24-19, 02:06 PM
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I have a new thermostat I am trying to wire right at the furnace as the extant one only had 2 wires ran to it
I have a picture of what I have at my furnace I can email you

thank you
 
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Old 07-24-19, 02:11 PM
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Picture of what I have at furnace

I removed old thermostat and only had a 2/22 wire red/white
(I have ran a new 5/22 wire)
Looked at furnace wiring and have 2 black wires from Fan limit switch (one on 24vac transformer other on gas valve terminal)
White wire to thermostat on other gas valve lug, then red wire from thermostat to other terminal of 24vac transformer
I don't see any fan contact wires.
So my question is how do I wire in the new AC condenser and also be able to turn the fan on and off if wanted?
 

Last edited by smbaz; 07-24-19 at 03:33 PM. Reason: more info
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Old 07-24-19, 06:58 PM
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smbaz is trying to control 3 circuits, heating, AC and fan with one thermostat switch.

Get a modern programmable heating/cooling thermostat. I bought a spare on ebay last month for $16. Supplyhouse.com is good source for new ones:
https://www.supplyhouse.com/Thermostats-327000

They make wiring easier, more economical system operation and more comfortable home.
 
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Old 07-24-19, 07:17 PM
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Welcome to the forums.

Right off the bat you need a fan center. You need the relay it contains to control the 120v blower.
There are ways of kluging it but a fan center is a better choice.

Fan center
 
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