A/C Blowing Hot Air

[ChevyHDGert]

My A/C just started blowing hot air today.

 

You know how air comes out of the vents when the HVAC system is off? That is how I discovered it cuz it's not hot enough to need to turn on the A/C yet.

 

The system was off, the knob was on blue and hot air was coming out. So I turned on the A/C and it was still blowing hot air.

 

Blown fuse?

Low on freon?

Bad sensor under the hood?

Bad sending unit?

[90GMCZ71]

My A/C just started blowing hot air today.

 

You know how air comes out of the vents when the HVAC system is off? That is how I discovered it cuz it's not hot enough to need to turn on the A/C yet.

 

The system was off, the knob was on blue and hot air was coming out. So I turned on the A/C and it was still blowing hot air.

 

Blown fuse?

Low on freon?

Bad sensor under the hood?

Bad sending unit?

 

<{POST_SNAPBACK}>

 

 

 

Start with the basics:

 

1) Is the belt still on the compressor?

2) If so, does the compressor cycle on and off?

3) Belt is on, compressor does not cycle. Could be low on r134a or the cycling switch is bad, or electical (fuse, relay or wiring).

 

Post back what you find.

 

//90GMCZ71

[ChevyHDGert]

This happened yesterday during lunch break and I never restarted it when I got back to work. But when I got off work yesterday at 5, it started working fine again, blowing cold air.

 

So who knows, maybe just a glitch.

 

Thanks for the help anyways.

[naui]

I've had the same problem with my 2000 sierra 2500 6.0L engine. My A/C also started working again after leaving the truck sit for a few hours. I brought the truck in to have it checked and they found nothing.

[CREW03HD]

I've had the same problem with my 2000 sierra 2500 6.0L engine.  My A/C also started working again after leaving the truck sit for a few hours.  I brought the truck in to have it checked and they found nothing. 

 

<{POST_SNAPBACK}>

 

 

Ihad that problem took it in to the shop found it was low on gas put some in ran fine then 2 days later same thing took it back they replaced the low pressure switch on the fire wall solved problem but who needs ac now it is 30 degrees.