Express 2500 360,000m The air from the a/c is cold, but slowly disappears until it stops. Flipping over to the settings with no a/c, the air comes back in around a minute or two. flipping back to a/c its cold and strong, but again slowly goes away, over10-15 minutes. Blend gate seems fine, Motor does not slow, just no air coming out the vent. I removed the blower motor to check. However I did find this thing attached to the blower motor, not looking so healthy. A thermostat?

 

That is the blower motor resister, which allows for the 3 different fan/blower speeds. Usually when that component dies, you can't get the fan to run at the lower speed settings...it will only run at the max setting. Those were the symptoms of my blower motor resistor failure....could only get the fan/blower to run at the max setting. Its an easy job to replace it, and that fixed the problem.

Regarding the air flow steadily reducing when you run the AC, I experienced a similar issue, but it was during a 14hr drive from AZ to TX. In my case, I am convinced that the evaporator iced up and blocked the air flow from passing through the cooling fins. Once I turned off the AC and just ran the outside (105+F) air for a few minutes, the ice melted and normal flow resumed. Turned the AC back on, and all was good again, but further on down the road, it iced up again and I had to repeat the process to get the air flowing again.

Peter

 

Burned out resistors is likely a sign that the motor itself is on its way out.

 

First, what year are we talking about?

The resistor on my Astro would melt the jack connection if I used it on high a lot.

I'd go back to the blend door. The next time it happens, try leaving it on the "no A/C" setting and see if it fades then.

 

The air blows continuously when its on a "non a/c" setting. Its hard to see in the pic below, thru the resistor unit hole, but there is ice on the condenser coil, and this other thing. Not sure if this is normal. Its my first go round with a/c. Maybe just take it to an a/c specialist is best.

 

the ice formation makes sense. when it ices up it will stop all airflow going thru the evaporator.

depending on the model year...the system uses either a pressure transducer or a low pressure switch to stop ice formation. Pressure and temp are directly proportional...so the system will shut off the compressor to prevent icing when the pressure gets to low.

if your compressor never cycles off, someone has probably jumped the switch or the transducer/related wiring is giving the pcm the wrong pressure data.

 

Thats helpful thanks. I have owned the vehicle since 2004, V8 6L. Recently swapped engine and trans for used one 70,000m. This started long before that, so probably not a shorted switch. Where is the pressure switch located. A/C is definitely not my field

 

what year

 

Sorry, that's a 2004

 

The low pressure switch is in your photo to the left of the reciever dryer.... it has 2 wires connected to it......

Hi Guys.... Stan.....and Mountain man