My 1 1/2 year old trane heat pump is not blowing warm air when the heat is on. Also, the fan does not turn off at the thermostat. Changed out the thermostat and the heat seemed a little warmer (not much) but fan still does not respond. Any clues?

If your thermostat has a fan switch, turn it to off next time it happens. If the fan still continues to run it is more than likely the fan relay that is sticking. Depending on your skill level you may be able to change it yourself.
If not, it should be a fairly inexpensive repair from a local HVAC contractor.

They say its hard to stop a train,, I guess not

It sounds like you have a couple of problems-possibly. Being only a year and a half old, I would contact the Trane distributor that installed it. IIRC, Trane is now warrantying all their parts for 5 years, and you may be entitled to free replacement as well, depending on your contract with the installer.

As for the problem... MissouriBound has a likely scenario-a stuck relay. The problem is that this relay is located on a pricey little circuit board.

The low heat is another item completely...

With the compounded issues, I recommend you contact a Trane dealer to remedy it. Yes, TRANE... as Trane is built to a higher standard, and is a bit more complicated to work on if you haven't been properly trained (traned?LOL) on them. I don't mean to pass the buck, but if you want it done properly AND quickly, all roads leat to a technician on this one.

And don't forget to pursue the warranty angle-aggressively!

Good Luck, and I hope this helped.