I've got a Carrier Crusader. During the summer...the blower would not kick on even though the coils were cold. I had a tek come out and service the unit. He fixed (more or less)the problem by installing a RBM TYPE 91 Relay 90-340/91-901 coil 24 VAC. He said he saved me replacing the whole board by installing the new relay, but he by-passed something in the meantime and mentioned there may being an issue when it comes time to turn on the heat. Well, we tried the heat today, and wouldn't you know...the blower didn't work! Suprise! I noticed that the relay has 7 electical posts on top...two heavy wires (black and brown) are connected to two of the three posts on the front. There are two lighter wires (green and yellow) connected to two of the three posts on the back of the relay....there are two posts in he middle. Is this a matter of just moving the wires around to different posts to make the blower kick on for heat? I've run the self test and everything works in sequence exept the blower. Hope this makes sense....Mike