Air Conditioning - Can I wire a thermostat for cooling only?

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mfrancle
08-16-06, 12:18 PM
I am replacing a White-Rodgers thermostat with a Honeywell Round thermostat model # T87F 1859. I did not order the subbase and was wondering since I am only using a Heil horizontal heat/ac unit for cooling only if there is a way I can wire the thermostat for cooling only? The new thermostat only has 3 wire hookups (R, W & Y) and I currently have four wires hooked up to the old thermostat (G, R, W & Y). Thanks for any help.

Ed Imeduc
08-16-06, 12:25 PM
Yes you can .BUT BUT
You need R for power
Y for compressor
G for fan

All 3 W is for heat

ED
mfrancle
08-16-06, 12:41 PM
Ed,
I'm confused then. On the Honeywell thermostat I only have hook ups for R, Y and W. Not one for G - so how do I go about hooking it up? Thank you for the help.

Ed Imeduc
08-16-06, 12:58 PM
The T 87 has a base with it. You put that on the wall wire it then the T87 gets put on the base.
R is power so when trhe tstat called for cool it turns on Y the compressor and G the inside fan.
Also the base has the fan on --or fan auto on it.
If you just want to play with itR is power. Put the Y and G on Y Thats how it work anyhow.

ED
Jay11J
08-16-06, 03:59 PM
I agree with Ed on what he said. With out the sub base, you lose the fan "On-Auto" feture.
Grady
08-16-06, 06:38 PM
This thermostat as shipped (without sub-base) is for heating only. For cooling applications you need a sub-base Honeywell #
Q539C-1020. This is a cooling only sub-base & has R,G, & Y terminals. For heat/cool you need either a Q539A-1147 or Q539A-1014.