I think have a strange problem with my A/C. I have EATC. When I push MAX A/C, air blows out of the foot and defroster vents nice and cold, but on really hot days, I'd rather have the air blowing through the dash vents, so I push the vent button and set the temperature to 60. The air never gets cold, but almost feels like it's gradually warming until the temperature almost feels like outside ambient.

I remember hearing a popping noise from behind my dash a few times last year, so I suspected the blend door. Before I tore apart my dash, I ran the EATC diagnostic and came up with nothing.

Stupidly, I took apart my dash yesterday, and the blend door is undamaged, and the actuator moves (I'm guessing) normally.

Since the dash is already apart, I went ahead and bought a new blend door and actuator, but why is the air warmer on anything other than MAX A/C?

 

MAX AC uses recirculation (cools air already inside the truck)

you could be low on refridgerant and it just can't keep up with cooling hot air from outside


The 2003 EATC is rebuildable, you have to replace O rings inside the headunit

 

Cool. I'll look inside the EATC. Might as well make sure everything is good to go for the humid Tennessee summers.

I'm not sure if I'm low on refrigerant. I don't have any real gauges, but when I hooked up the AC Pro can, it read 30 pounds on the low on an ~80 degree day. I only had a few minutes that day, so I filled it to 40, which was below indicated optimum on the idiot gauge.

The symptoms I described are still there after I used the recharge can.

 

My guess is the orings in the eatc like it was stated

 

The o-rings in the EATC don't have anything to do with temperature control. Vacuum controls the damper motors for outlet and recirc selection and the o-rings are in the vacuum-switching solenoids.

Temperature control is done with an electrical motor.

 

He's got cold air out of the defrost and floor?

 

 

Yes, that indicates that the EATC is not switching the vacuum door(s) correctly. EATC o-rings are a distinct possibility for the incorrect airflow outlet symptom although there are additional possibilities.

 

So, should I try to find another EATC in a salvage yard?

 

no, a similar age unit likely also needs to be rebuilt

 

I have some more info... not sure if this changes the original answers...

The AC clutch doesn't engage when the vent button is pushed. Defrost and MAX AC do engage the clutch.

Guess that explains the ambient air temperature?

 

here's how the manual ***** are setup

Max AC (clutch yes)
A/C (clutch yes)
Panel
Off
Panel/Floor (clutch yes)
Floor
Floor/Defrost (clutch yes)
Defrost (clutch yes)

 

I don't know anything about the EATC but as far as refrigerant goes, don't trust the gauge on those stupid AC Pro cans. Last summer my wife's Acadia just wouldn't cool or stay cold so I bought one of those AC Pro units to do it my self. Hooked it all up and it showed I was above max for my unit. Had my neighbor take a look at it who is a retired GM mechanic, same thing. He said you can over fill them but in my case it had to be low on coolant, took it to the shop the next day and yep, a shot of coolant and $50 I was back in business.

 

Yea, I don't really trust the can gauge. My A/C is working just fine, just not with the vent button. Within reason, I just make sure my system isn't leaking and then fill it until the vents are blowing as cold as I remember.

I would hope that the vent button on the EATC is designed to engage the clutch, because if not, then there's no way to manually get cold(er) air out of the dash vents.

I might just get another unit out of the junk yard to compare. I would like to solder LED's in the EATC, and a backup would be nice.

 

Vent is vent from outside.

AC still blows through the vents when set on AC.


Sorry im not super familiar with the ins and outs of the EATC