What makes heater suddenly stop working but ac works fine

SOURCE: Heater, AC & radio suddenly stopped working....

Fuses are in the kick panel on the passenger side. If it blows again, you will need to find the malfunction (don't put in a higher rated fuse) Most times the blower motor will cause fuse failure as when the motor gets older it begins to draw excessive amperage...but don't change it till it is actually verified as being bad.

SOURCE: My heater.defrost/ac suddenly stopped working.

check the fuse

SOURCE: the blower motor for my 2005 Suburban suddenly

Check voltage at the terminal that connects the blower if the problem is the current blower because eventually the brushes wear out

SOURCE: heater only blows cold air

Check your rad and make sure it is full. Wait til truck is cold before removing rad cap.

SOURCE: my ac was working fine

There is a blender that controls the air flow to go through the heater core for heat, and the evaporator for AC. It very well could be stuck.

You maybe able to try and get it to get unstuck by running the cars AC and switching from heat to AC back and forth and see if it gets unstuck. Just turn it on full blast and go from heat to cool.

If that fails, then you may need to service it. There should be a Lever Marked VENT under the dash, usually by the Brake and other pedals on the Driver's Side. Close the VENT and that will stop the Air from coming in and leave the A/C Blowing through the outlets(Vents).

I also read this online if you have an electronic climate control. "On climate control press off and heat button and let go quickly. Then press automatic. The display will start rotating eventually displaying a code 025,125 , 024 etc. Then press defrost to stop. You may hear blend door operating atb that time. It worked for my climate control."