Panning after recording

Ok, I'm new to this so please bear with me.  I have a two channel sound card, and I'm recording with my mic in the right input.  I set my input (in sonar) to the right channel (not stereo).  During playback, I can hear sound mostly on the right.  But as I'm listening, if I pan all the way left, I can still hear sound, but it sound very light with no low end (kinda like AM radio). 

My question is this:  Is it possible to record in such a way that I'd be able to hear the same full sound no matter if I pan left or right?  And if not, then how am I supposed to mix vocals in the middle if the sound is "heavier" on one side?

Yes...actually, it's only through the headphones I guess.  I can't seem to tell a difference with the monitors.  It drives me batty when I record though.

Be sure you have the input set to MONO.

IN my system, Also a 2 channel interface.... When I click on the track control area (maybe double click), a box opens that allows me to set my track inputs from the available options.

1 is stereo input, 2 is right input mono, and 3 is left input mono. This is the actual channels on my interface that I am selecting from inside the DAW, telling it what channel I have audio input coming in on.

Since I am a creature of habit, I have my guitar plugged into the interface on both channel inputs... but forget about that. I have a POD2 that supposedly has stereo FX available BUT...... I simply treat it as a MONO instrument.

SO..when I choose my input for the guitar channel, I ALWAYS choose the LEFT MONO input. This send the signal to the track as MONO, and centered equally on the R/L panning.  If I need it to one side or the other I can move it from center of the sound stage.

I think your problem might be that you are selecting the stereo input option. try the MONO and see if that works. If I recall, the setting is stereo by default so when I'm in a hurry or forget to select MONO, I get TWO lines/channels in the track when I record, and the Left channel is the only one with audio.