The light is out behind the round heater switch/defroster switch. How do I get behind to replace it?

This could be a serious problem if the smoke smells like plastic or has a metallic hint ( I.E. You have a metallic taste in your mouth after smelling the smoke).
Remember the old adage " Where there's smoke, there's fire".
If you don't know how to disassemble the dash to find the problem, take it to a shop A.S.A.P. - You could burn up your vehicle by using either the heater or defroster, as they are parts of the same system.
Now for the rear defrost light;
If the light is out but the defroster works, you possibly have a burnt bulb. You'll need to remove the panel the switch is mounted in to gain access to the switch. You'll probably have to replace the switch to repair that bulb.If neither work, then you likely have several electrical issues that need to be repaired.
Sorry to bring bad - ish news!!

you don't have to replace the heater but get a new heater control switch and install it then all should be right as rain. Good Luck

Sounds like the blend door. The actuator motor is located on top of the box (behind the glove box) and is notorious for failing.

the blower motor is by the passenger side floor kinda below and behind the glove box should be able to get to it from underneath, remove any plastic covers u may encounter. the box which holds the motor has a round section to it and u may see 3 or 4 screws going straight up into the box from the bottom. we want to check power before we assume the blower is bad. there will be two medium gauged wires plugged into the round part of the box. if u dont see the two wires there, pull the glove box down and looks behind it. when u find the wires backprobe the wires at the connector and hook each end into a test light. turn the fan switch on and if the light lights up then u need a motor because u have power and ground to light up the light and the motor still wont run. if the light doesnt llight up and ur sure ur making good contact then u may have a bad switch. tip for life: whenever ur blower works on high speed only, then u need to replace the resistors which those two powere wires are coming from also bolted near the motor in the heater box

Check the vacuum going into the firewall under the hood,then check the vacuum switch behind the ac heater control.

does it blow through the defrost vent only when you switch to vent/floor or does it blow through defrost and vent/floor? is it a switch that is just electric or a manual lever that you slide? the manual type will have that problem if the diverter or the linkage behind the lever(in the dash behind the panel......may be able to access underneath) becomes broken or disconnected so that the air is diverted to defrost regardless where you move it.if you can get to it, you will see what is broken or maybe a fastenerr fell off.

replace dimmer switch and replace bulbs behind heater control good luck.

Get a female garden hose adapter from the local hardware store. Disconnect the heater hose from behind the fan pulley and attach the hose connection. Disconnect the other heater hose behind the alternator, aim it towards the ground and flush water through the heater core. This worked on my truck.

your switch should have a few cables behind it if you can slide out your radio you can reach them to change it to fefrost easly

if the fan does'nt come on at any speed have the fan checked if fan is good check the switch if on good replace fan switch located inside there is also a regulator under dash behind the glove box if the fuse's,motor & switch are all good this regulator the last comp. in the heater circut or you have a broken wire. hope this is helpful