Heating question

I have a 01' sebring with the 2.4
dohc motor. About a month ago
the car overheated and I checked
the coolant and it was low. I
added coolant, replaced the
thermostat and pressure cap and
notice a very slow drip under the
car. I just kept adding water once
in awhile to keep the coolant level
up. A week ago I replaced the
pcm in the car because I had the
check engine light on since I
bought the car a few months ago,
I had the code read and it csme
back pcm failure so I replace it
with one I purchased online that
was programed with the vin
number. At the same time I
replaced the pcm I drained the
coolant and replaced it with
50/50 mix because I had used
straight water in it and the temp
outside is getting colder. After
doing all this my heat doesn't get
warm now. I checked to see if the
heatercore hoses are getting hot
and they are. I also even tried a
climate control recalibration
technique that I found on another
site, it went through the process
but still no heat. I'm confused
because the car is no longer
leaking coolant and doesn't
overheat. I had bled the air from
the system when I drained and
refilled it. There was too much
coolant in the overflow wich I
removed and brought to the
correct level. Not sure if that was
the cause of the dripping.
The big problem now is no heat
because it's getting cold and I'll
be unable do defrost the
windows. Can anyone help me
troubleshoot the heating
problem?