2007 Lincoln Town Car Cooling only on passenger side

Try running these tests and see if a code shows up, or do the cold boot test and recalibrate the system. Here's the proceedure:
Electronic Automatic Temperature Control Module Self-Test à   The EATC module self-test will not detect concerns associated with data link messages like engine coolant temperature or vehicle speed signals. A scan tool must be used to retrieve these concerns. à   The EATC module self-test will detect concerns in the system control functions and will display hard diagnostic trouble codes (DTCs). Hard DTC's identify faults which are present during the self- test. The vehicle interior/ambient temperature should be between 4-32 °C (40- 90 °F) when carrying out the self-test. If the temperatures are not within the specified ranges, false temperature sensor DTCs will be displayed. à   The self-test can be initiated at any time. Normal operation of the system stops when the self- test is activated. à   To enter the self-test, press the OFF and FLOOR buttons simultaneously and then press the AUTO button within 2 seconds. The display will show the fan speed indicator illuminating from low to high. The test may run as long as 30 seconds. Record all DTCs displayed. à   If any DTCs appear during the self-test, follow the diagnostics procedure given under ACTION for each DTC given. à   If a condition exists but no DTCs appear during the self-test, refer to the SYMPTOM CHART Condition: The EATC System Is Inoperative, Intermittent or Incorrect Operation. à   To exit the self-test and clear all DTCs, press the FRONT DEFROST button. The EATC control assembly will then turn OFF (display blank) and all DTCs will be cleared. à   Always exit the self-test before powering the system down (system turned OFF). Electronic Automatic Temperature Control Module - Display Continuous Codes à   This function will display continuous (intermittent) codes and hard faults that occur during normal operation. à   To display continuous codes, press the OFF and FLOOR buttons simultaneously and then release and within 2 seconds press the RECIRC button. à   To exit the display of continuous codes, press the FRONT DEFROST button. This will exit and clear all DTCs. Press any button except DEFROST to exit without clearing DTCs set before the last ignition cycle. à   Always exit continuous codes display before powering the system down (system turned off). à   Continuous DTCs are saved only after an ignition cycle. à   Continuous DTCs will be deleted after 80 ignition switch ON cycles after the intermittent condition occurs. Electronic Automatic Temperature Control (EATC) Module Cold Boot Process The purpose of the cold boot process is to allow the EATC module to re-initialize and calibrate the actuators. To carry out the cold boot process, follow the steps below. 1. Clear the DTCs. 2. Turn the ignition switch to the OFF position. Post any codes that show up. Question for you, do you have a manifold gauge set? Often with dual zone systems, the charge lavel is low.2007 if never recharged may be just a tad low, all A/C systems loose a small amount of gas out of the service ports.