Carrier RTU Heat Pump Question low voltage wiring Question

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Carrier RTU Heat Pump Question low voltage wiring Question

Post by juniorkarrie » Tue Jan 04, 2011 10:40 pm

Hello, I have officially been stumped on this RTU. (Model 50TCQA) Well anyways I need one simple question answered, Does this model RTU require a "PremierLink, or a RTU-MP Controller" in order to work properly? I attempted to start-up this unit and initially thought I had a defrost control board issue. The unit was wired like a normal Heat pump except on the Control board there was no "O" terminal, so I did the next best thing and wired it to the "W1 - 1st stage Heat" and programmed the T-stat " Carrier Debonair 420" to Heat pump. When the unit came on in the heat mode the Compresor contactor engaged but the reversing valve also engaged with no power going to the "w1" terminal. So I began checking voltage at the pins, Ohming the DFT and so on and so forth but in the end I concluded that the Defrost board must have a stuck relay or something of that nature beacuse it wasn't getting the 24 volts from the Control board but coming out of the defrost board trust me I traced it. So since It was not a complete emergency I just wired this thing up in emergency heat only. Once I got home I want to double check my Diagnoses so I began looking over the manulas and discovered some pretty interesting things.

1. I was missing Page 14 "low Voltage Wiring Page" which was not included in the Manual that was delivered with the unit, it went from Page 13 to 15, simply not stappled in the book.
2. Once I found the manual online I read that this particular unit does not need the "o" terminal engaged and T-Stat set up like a simple "Electric Heat" and it will work like a heat pump.
3. They gave a wiring diagram but that also threw me off, all the abbriviations "R-Y1-"Y2/O/B"-W1-W2-G-C"seem like normal everyday Connections except one. "Has anyone seen this Before?"

Can anyone answer or give me some Advice? Thanks for looking

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