I recently bought and tried to install a new Honeywell rth8500 to my Whalen Series VI 801 heat pump. I have 4 wires: R, Y, B, and G. Seemed pretty straight forward to install and I connected R to R (bridged to RC), B to O/B (also tried B to C as suggested by the manual), Y to Y, and G to G. The fan works fine but the system doesn't emit any heat or AC. I rewired the old stat to see if it was the new stat malfunctioning and now the old stat won't give me heat either. Is there some heating control I could have somehow turned off? Any other suggestions as to what I can do to fix this?

Thanks in advance!

Anyone have any ideas?

Turns out the relay that takes power from the safety switch was shot and needed to be replaced. Pretty quick fix once the tech figured it out. Cost me a couple hundred bucks though in labor for the tech to figure out what the problem was...