Changed batteryand now the hvac lites are on - 1998 Dodge Caravan

Have you checked voltage and ground for blower motor? in the diagram, the top wire at blower motor is voltage. The purple wire, bottom wire from blower motor is ground. You can see blower fuse at the top, hot all the time. The blower motor on/off, different speeds are controlled on the ground circuit. You can take two wire connector loose from blower motor, use both ends of test lite at wiring connector terminals, turn on key, turn on hvac and blower controls, if the lite comes on, you have voltage and ground. If good voltage and ground with no blower action, suspect the blower motor. I couldn't post whole diagram and make it readable. The problem could be almost anywhere, with the wiring? I can only help with testing. good luck

This is manual hvac for your vehicle, don't know if hvac is manual or auto. Take blower motor electrical connector loose, use a test lite between those two terminals on connector, key on hvac on, does the lite come on, if it does, may be something wrong with blower motor? At the blower motor in diagram, top wire is voltage, bottom wire is ground. For testing you might be able to use jumper wire to clean metal spot from that bottom wire at blower motor. If it runs the problem is on the ground circuit. When checking fuses also use a test lite at fuse to check for voltage, two of those fuses are hot all the time, two of them go hot with the key on. Check for hvac trouble codes, where applicable?

Actuator Recalibration
Important: Do not adjust any controls on the HVAC control module while the HVAC control module is self-calibrating. If interrupted, improper HVAC performance will result.
Alternate Method (w/o Scan Tool)
Clear all DTCs.
Place the ignition switch to the OFF position.
Install the HVAC actuator.
Connect all previously disconnected components.
Remove the HVAC/ECAS fuse for a minimum of 10 seconds.
Install the HVAC/ECAS fuse.
Start the vehicle.
Wait 40 seconds for the HVAC control module to self-calibrate.
Verify that no DTCs have set as current DTCs.

This is the electrical side of your ignition switch, not the lock cylinder.

This is for front blower motor. The orange wire is voltage, hot all the time, fuse protected. The black wire is chassis ground, you can check both those wires with test lite. The top wire, control from hvac control module. That may be a pulse width modulated signal? This was for automatic hvac w/o roof.
bbbind.com has free wiring diagrams.

gain room by pressing on right side of open glovebox. it should come off its hinges. just set it aside. you can see the HVAC box. Look on top of the HVAC box and a little to the left and you will see the blower motor resistor mounted snuggly. have a good day !

2 wheel drive or 4 X 4 ? Automatic or manual climate control
Do you know what DTC'S - diagnostic trouble code's are ?
DTC B1375
The ignition 3 voltage circuit is a discrete input to the HVAC control module. The HVAC control modules uses the input to determine that the ignition switch is in the RUN position. When the ignition switch is in the RUN position, ignition voltage is applied to the input.
Rather then guessing as to what the problem , not being able to diagnose properly , your best bet mite be to have a qualified repair shop check it out . Would need to hook up a professional or factory scan tool to check code's ,see if the climate control module will communicate with the tool .
HVAC Control Module
The HVAC control module is a class 2 device that interfaces between the operator and the HVAC system to maintain air temperature and distribution settings. The battery positive voltage circuit provides power that the control module uses for keep alive memory (KAM). If the battery positive voltage circuit loses power, all HVAC DTCs and settings will be erased from KAM. The body control module (BCM), which is the vehicle mode master, provides a device on signal.

Having the same problem. Anyone that can help

If you mean the heater core is leaking. Here is how to change it:

Heater Core Removal & Installation Heater core removal

To Remove:

1. Remove the HVAC assembly.
2. Remove the heater core cover screws.
3. Remove the heater core cover from the HVAC assembly.
4. Remove the heater core gasket from the core.
5. Remove the heater core from the HVAC module assembly.

To Install:

1. Install the heater core to the HVAC module assembly.
2. Install the heater core cowl gasket to the HVAC module assembly.
3. Install the heater core cover and screws to the HVAC module assembly.
4. Install the HVAC module assembly to the vehicle.

u have to get new or used control head