HEATER WONT BLOW THREW VENTS ONLY BLOWS THREW DEFOGGERS

With the computerized vehicles now, it can be something quite simple, or something major. Hard to tell without the instruments to test it.

I am not sure if it would need rebooting or not, but you may want to check for a switch at an auto store, and get directions on how to uninstal/reinstal the switch. If you can do that without the rebooting then it should fix it. Most likely the switch just redirects the airflow under the dash to the different tubes where it is supposed to go.

As by heat only works some of the time , you mean it doesn't blow air out of the vent's . This means you probably have a problem with the blower motor or blower motor resistor or blower motor relay .
Rear Window Defogger Inoperative

Exchange the rear defogger relay with a known good relay from the under hood junction block.
1. Turn the ignition switch to the ON position.
2. Press the rear defogger switch to the ON position.

Does the rear defogger grid warm?
--
Yes Go to Step 2
NO Go to Step 3

2

Replace the faulty relay.
Is the repair complete?
Go to Defogger System Check --

3

1. Use a fused jumper wire in order to backprobe between terminal A4 of underhood junction block connector C3 and ground.
2. Use a test lamp in order to backprobe between terminal C5 of underhood junction block connector C3 and ground.

Does the test lamp light?
--
Go to Step 4
Go to Step 23

4

1. Use a test lamp in order to backprobe between terminal C5 of underhood junction block connector C3 and ground.
2. Press the rear defogger switch to the ON position.

Does the test lamp light?
--
Go to Step 5
Go to Step 14

???the vents are in the dash . yes??? are you asking the ac to blow out on the floor , as typically they don't do that , only the heater does that

no air blowing check fuses and blower for being bad ,if the air does not blow out the top but only coming out the dash vents like the ac does check for broken cable on the controller in the dash and also cable behind glove box whichg moves the doors inside the air box

need to make sure you have enough coolant and if it does then it could be your thermostate or clogged heater core

I'd have to say it's the blower motor. Does it blow hot air when the heater is on?

This car has a "vacuum module located behind the control panel.Make sure all the vacuum lines are connected.

your blower resistor bad or the blower motor control switch is bad. no air flow from top vent make sure vent open.because you can manual adjust them not to blow air on you.if all is good.you have leaking vacuum hose or vacuum actuator.or air door stuck.the AC and HEATER control switch.is bad.its not allowing vacuum to open air door.

check for vacuun leak at thefront inside the engine coparment

Try pulling trouble codes first. Run your car at idle with the blower control set at anything but off, the temperature in full cool and the right knob in defrost mode. Push the rear window defogger button until the instrument panel reads AC00. The BCM will chime and the A/C button will blink. Release the defogger button and wait until the A/C button stops blinking. The trouble codes will show up on the odometer. There isn't a vacuum hookup that I know about as these are electrical. Anyway, write down the codes and call a dealer or buy a service manual to interpret them.