heat furnace keeps shutting off then turning back on?

I have an old (don't know how old but at least10-15 yrs I would bet) Trane Self-contained (compressor and blower are in the same unit) HP. It's say's Trane Weathertron but any other outside stickers are too faded to read. Yesterday I noticed that the "Front" fan next to the outside coils wouldn't shut off but the blower fan would. On/off switch on thermostat wouldn't shut off system neither would switching from auto to fan only. I had to throw the circuit breaker. Today it was chilly so I turned on the CB and the compressor fan started up, went into the house and turned the switch to heat; fan switch was on auto and the blue light came on; the blower fan came on and warm air was coming out of the registers. I turned the temp way down and the blue light went out, the blower fan turned off but the compsessor fan in the "front" of the unit still ran and won't shut off unless I throw the CB off?

I had my Trane 2TEC3F30A maintained this morning. Everything checked out ok (it was just routine maintenance). After the tech put things together, the circuit breaked tripped and stopped working. She eventually got it working. She said she "tripped" the transformer and simply had to reset the breaker. I noticed that instead of two red transformer wires connected, only one was connected. I could have sworn that both were connected when she was cleaning it. I am not even sure if the transformer is the original one. I have a picture of another transformer which i suspect is the original one. She was able to get the unit to run/heat. Questions: 1. What are the implications of using just one of the transformer terminals? Will it heat less efficiently? 2. What is the transformer for? Is it just a switch? It appears that other transformer connectors are connected to the thermostat. 3. What is the use of the other terminal? Is it for the AC? 4. Do you have a circuit diagram of this portion of the air handler? 5. Should I call back the company? or should I go with another trane dealer?