I have a 1996 deville and the heater doesnt work. A/C works fine the blower blows cold a/c but when i turn on the heater it only blows out by the floor boards and it is cold. the vents dont work only when the heater is on. could that be a coil or??? any help would be great.

If your low on freon then the A/C wont come on? for a 1996 you will need to get it serviced if you havent its normal to loose 10% freon a year,

im not sure if you mean the blower is'nt working or if you mean the blower is working but the air is cold so I'll try to answer both, if the blower is'nt working it is possibly a bad fuse, the fuse panel may list it as the heater or it may say blower, now if its blowing but the air is cold it is most likely a bad thermostat, sometimes the heater core goes out but if you havnt noticed the window fogging on the front windshield on the passenger side or smelled coolant in the cab of the vehicle the heater core is probably fine , the thermostat is a common culprit and they are fairly easy to change, one other thing before you go changing anything, check to make sure the radiator is full, with the car cool take the radiator cap off and run the car until it starts to get warm and see if you can add some coolant

Follow the wires from the blower motor back to the blower motor resistor, normally only a few inches away and held in by a 7 mm screw. Replace it

HAVE BATTERY VOLTAGE CHECKED.MAKE SURE BATTERY IS FULLY CHARGED IT SHOULD BE 12.5 VOLTS.IF YOU HAVE DIM TURN SIGNAL LIGHTS.EITHER YOU HAVE WRONG BULBS OR POOR GROUND ALSO THE WEAK BATTERY OR UNDERCHARGING PROBLEMS HAVE ALTERNATOR CHECK OUT. FOR THE BLOWER MOTOR.CHECK FUSE AND RELAY. IF BOTH GOOD YOU HAVE A FAULTY AC + HEATER CONTROL SWITCH.OR THE BLOWER MOTOR IS FAULTY.REMOVE BLOWER MOTOR HOT WIRE IT USING A JUMPER WIRE TO BATTERY.IF IT RUN YOU HAVE SWITCH OR WIRES TO SWITCH PROBLEMS. IF BLOWER MOTOR DONT RUN.REPLACE IT AND BLOWER MOTOR RESISTOR.NOW IF WIPERS KEEP WORKING WHEN YOU TURN THEM OFF.YOU HAVE A FAULTY SWITCH OR DEFECTIVE LIMIT SWITCH IN THE MOTOR.

heater wont turn on

INADVERT Relay next to the engine compartment fuse block on drivers side i need one to

yes the A/c fan and Blower are the same thing. If your Compressor is kicking in but your not getting it to blow at all it could just be your fan switch. I hope this helps you out and please rate my solution.
Thank you

it is prob. the a\c/heater blower. yes they are very different

There's a blower motor (fan) under the hood and up against the firewall near the center of the car that takes some work to remove. It has gone out in the last 2 of my 4 Cadillacs. Turns out if you're not real careful with the positioning of the spark plug wires they will brush up against it, and if one of them gets cracked or brittle it will "arc" and short out the blower motor. The a/c compressor should still come on (you'll hear a click when it engages) but you won't get any air blowing into the cabin, hot or cold.

The part was like $200 stock (year 2000 prices) and it took about an hour to remove it. My Caddy at that time had this damn strut bar going across the engine bay which we eventually removed to get to the blower motor.

I had the same problem in my 1991 caddy, and turned out to be the blend door. It is located in back of the glove compartment. There are two kinds, the automatic blend doors and the manuel ones. Since the temperature is automatic and programmed to stay where it is set, it would be an "automatic blend door". Not a hard fix...