1997 Cadillac Devile. With AC on; cold air on passenger side, hot air on drivers side.???

DTC B1340 Air Mix Door #1 Movement Problem !
The heater and A/C programmer supplies voltage to an internal motor that drives the air mix door. The heater and A/C programmer monitors the air mix door position feedback from a sensor on the motor. If the air mix door is requested to move but the feedback voltage does not change, the heater and A/C programmer will store DTC B1340. If the air mix door feedback indicates that the feedback is near the hot or the cold extreme, the DTC will not set. Evaluate the operation of the air mix door through self diagnostics as described in the test description.
Test Description
Perform the Diagnostic System Check before continuing with the diagnosis of this DTC.
A Scan Tool allows for the direct control of the air mix door by observing the following conditions:
• The air mix door position feedback value
• The value`s difference from the air mix door commanded position value
These readings indicate a fault internal to the heater and A/C programmer in the air mix door sensor feedback.

Did you perform the Diagnostic System Check?
--
Go to Step 2
Go to Diagnostic System Check
2
With the engine running, connect a Scan Tool .
Turn the dual zone to OFF (passenger temperature offset at 0 or OFF).
Exercise the suspect actuator using the temperature control on the control assembly.
Is the door being commanded (COM) to the proper high and low values?
COM High 100 %
COM Low 0 %
Go to Step 3
Go to Step 4

If you are unfamilier with this , i suggest you take it to a ASE certified repair shop or the dealer .

many cars automatically kick on the air compressor in defrost, to dehumidify the cabin air

Check behind heater control for vacume leak to actuator or use a vac. pump on the actuator to see a difference.

In most cases the problem is a stuck or faulty blend door under the dash. You may have to disassemble the ac-heater box to access the door.

clean ur air fillter or vents

On the central console is the A/C module. Inside A/C module are driver's side & passenger's side air flaps for mixing hot & cold air and directed air flows towards driver's side & passenger's side according to driver commands. The passenger's side flap for mixing hot & cold air according to driver commands is bad. Flaps are actuated by electrical step by step motors. Could be damaged the flap actuator (motor), the flap mechanism (blocked in "HOT" air position), and / or electrical supply wires. You must access the passenger's side flap for mixing hot & cold air, and see what happens when you command cold air to the driver's side: flap mechanism, flap actuator, supply wires, ... Repair & replace bad pieces and test the A/C system.

One of the temperature actuators are not working it has 2, one for each side.

I had the same problem but it was blowing hot air on the passenger side of the car. I assume you have the dual zone controls that I have as well. The problem is most likely the damper that controls the flow of hot and cold air into the car. The motorized component of the damper is most likely not working and its stuck in the hot air position.

I had mine replaced by a repair shop so I cant tell you how to replace it but it may be something that you can do if you have the time and patience to work on it.

Good luck

The air doors are controlled by actuators that on of them or so may need replacing.

The temperature blend door on the driver's side might be broken or stuck. Also, if this vehicle does not have the correct amount of refrigerant, it will do what you are describing.