This afternoon my a/c quit blowing. All the way on, the motor doesn't come on, I don't feel any air at all. Now, when I switch the switch all the way off, the a/c light stays lit, before it would go off. The truck is an '05 Dodge Ram 1500 with a 5.7 Hemi, 4x4, 157K miles.

 

Could be a bad blow motor. Broken blend door. Bad control head. Blower motor resistor. Check fuses first. Then you May need to chase wires. Is the compressor coming on?

 

First, check your fuse box and fuses. Good? Proceed to 2

2nd, disconnect the plug to the blower motor and jump 12 to it to check the motor. Good? Proceed to 3

3rd, check for voltage before the fan motor resistor block (with the key on). Good? Proceed to 4

4th, trace your wiring and make sure all plugs are connected good. It is a good idea to disconnect each and test for voltage with the key on. Good? Go to 5

5th, check and replace ignition switch

 

I'm thinkin' the switch, too. If you're getting 12VDC to the resistor block, check the motor.

 

I know this is an older post but I finally fixed my issue. My controls stopped working and it was difficult to see going to work one morning. The A/C light would stay on even if the controls were off. I started moving the steering column up and down and the blower would kick on when the steering wheel would tilt down. My issue ended being the ignition switch. Swapping this also fixed my windshield wiper/high low beam multifunction switch. Hope this helps anybody who might have the same issues.

 

Thirdin switch. I've pulled one apart before. The design has small metal pegs that follow raised and lowered plastic tracks. As the track dips, the pegs lower and make contact, sending current. Problem is, the HVAC peg gets so hot it melts plastic as you turn the key from on to off, eventually killing that track all together.

Edit - Found an old switch. Here's the failure mode I'm talking about

I believe this one I've sanded the channel to allow the blower to turn on, but it failed again shortly after.