Just started a new job and got saddled with an older troublesome carrier air handler that was not working.first of all the condenser is disconnected and only the air handler provides strip heat to a small office.I found 24 volt transformer melted in the air handler.I replaced transformer and was able to get the blower to run but as soon as you flip the t-stat to emer heat the transformer smokes what could be causing this problem please help.could it be the heat strips causing this?

Sounds like there are some major wiring errors or shorts somewhere. First, disconnect any wires out to the condenser and make certain everything in the air handler is wired like the schematic on the access panel. Then make certain the thermostat is hooked up correctly. This should make the air handler work correctly and the electric heat do it's job. Last of all, hook up the condenser and trouble shoot it (better yet, do that in reverse order). Could be several things wrong, and without being there, it is hard to give a better answer. I assume you will be able to do the troubleshooting as you go along. I didn't give EVERY step that I would take, it would take a lot of typing. If you aren't certain that you know enough to do it correctly, call a technician.

EPM

It only takes 3 wires to make the older system work on heat strips, 2 if the sequencer brings on the blower. R to W will bring on the aux heat, R to G will bring on the blower R to W to G will bring on the heat with the blower. Add a 5 amp automotive fuse in line of the load side of the transformer using spade wire connectors. This will keep you from blowing the transformer. Start your process of elimination.

Watch for this one in commercial spaces:

Somebody yanks on a t-stat wire that doesn't have a grommet in a metal stud. ---> Short in tstat wire

If the condenser is disconnected, are the low voltage wires just laying around, touching each other, creating the short?