OK, I did some digging on your system...let's start from the beginning. Here's what I want you to do....
First, disconnect the negative battery cable and let it sit for fifteen minutes. Then reconnect your battery, turn the key to the "on" position for 3 minutes...this lets the computer recalibrate the doors and perform its self diagnostic function.
Now, let's see if the computer sees a problem. You are going to put the computer in diagnostic mode by following this procedure:
Turn the ignition "on". Press the "off" and "passenger warmer" buttons at the same time, then press the "lo" fan speed button until you see "ACM?" displayed on the control display. Now press the "Hi" fan speed button...you should now see "ACM Codes?" in the display. Press the "Hi" button again...any stored codes will be displayed. Let me know what numbers show up, if any.
This system uses a single heater core and two independent doors. The doors should work in unison in all modes EXCEPT "Dual zone"...so try MAX Heat in any position OTHER than Dual Zone and let me know how that works as well.
The two rubber hoses you saw are for the heater core, and the two aluminum lines are for the air conditioning system. Another possibility if you are getting heat from BOTH sides is a thermostat that is not closing all the way when it should. I personally use an infrared temperature gun to measure the temperature of the heater hoses going into and out of the heater core. This can tell me real quick if the coolant just isn't hot enough to begin with or if there is a restriction to flow in the heater core itself.
If you decide to take it to a shop, use the Shop Finder feature on this site to find a good one:
Let me know how you make out...one way or the other. Take care...
Hang in there...