3M-30 Thermostat On York Unit - HVAC - DIY Chatroom Home Improvement Forum

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Old 11-30-2010, 09:23 AM   #1
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3M-30 thermostat on York unit

I'd appreciate any help on this I can get. Yesterday afternoon it got a little warm so I flipped it from heat to cool (ambient temp had gotten to around 76 and we like it more around 74), unit and compressor kicked on and about 10 mins later I started feeling like I was getting hot flashes, I'm only 28 so this concerned me a bit. felt the air coming from the vent and it was heat. Checked the thermostat which was still switched to cool, displaying cool on the screen with a target temp of 74 and the room temp was up to 79 degrees! OK so, since I've installed the thermostat I've use the AC for about 4-5 days (worked fine), then we had a cold snap and turned it over to heat (worked fine), now that I'm going back to cool it's not changing over...
Here's my setup. (with pictures)
Old York thermostat wiring (that's White:W, Blue:B, Green:G, Red:R, Brown:X, N/A:H, Black:N/A, N/A:T, Yellow:Y, Orange:O)

York Unit info

Next are the pages from the 3M-30 Install guide that I used
Wiring reference

and the 5wire install that matched closest to what I have

and the actual wiring (Brown:C, Orange:O, White:W, Yellow:Y, Red:RH-RC, Green:G, Blue:N/A, Black:N/A) (not 100% sure about the White:W as the wiring diagram from the install manual says to do W2:W2 but I only had a W so I wiried it to W and not to W2)

and as for the dip switches, I'm set to NORM:HP* GAS:ELEC* EMER:OFF* (after it got to a sweltering 79, I switched the first dip switch from HP to NORM and the AC finally kicked on, Don't want to leave it there though because my unit is Heat Pump equipped)
In the wiring reference it states that if you have an O and B and it's not a trane unit to tape off the B and connect the O which is what I did, but this sounds like what might be the problem, since O and B have to do with the heat pump changeover. (just my 2 cents which obviously is not worth much
Thanks Guys,


191GA is offline   Reply With Quote
Old 11-30-2010, 04:40 PM   #2
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The blue wire should be connected to C.

The brown wire should be connected to W2.


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