Hi Gang... I have a '99 S-10, 4D 4WD, 4.3 L - nothing out of the ordinary, 202k miles. The AC pooped out, won't hold freon. All indications are that the evap is the culprit, no leaks detected under the hood. Not interested in tearing the dashboard out to replace it.
I noticed that the windshield defroster no longer works - the ductwork doors don't change position to blow air out the defroster vent. The fan blows like crazy, but no airflow up to the windhield. Is the function of that door dependent to the operation of the AC? Yeah, the AC normally kicks on to throw dry air at the fogged windshield, but it seems counterproductive to have NO function at all if the AC dies.
LMK what you might now about this, maybe a vacuum line has coincidentally cracked around the same time as the AC's death?
Thanks!
Ron

 

Leaky evaporators are not common at all on these vehicles. More likely a "belly leak" from the compressor, (very common problem, as in eventually they all leak there) Leaks can be easily detected using UV dye and a black light.

No connection between inoperative A/C and air distribution. Might be a vacuum leak in the HVAC vacuum lines, a bad vacuum actuator, or a stuck blend door.

 

rtk3: check the vacuum lines under the hood, especially at the left upper corner. If any of the hoses look cracked, replace it. I just bought 10 feet or so of hose and replaced all the lines under the hood...it was just easier to replace them all.

The air distribution is controlled by vacuum actuators. My '95 Blazer had a torn diaphram for the actuator that sent air to the dash vents....yours may have a similar problem. Hopefully it is just a vacuum line as getting to those actuators requires most of the dash to be removed.

Good luck and let us know what you find.

 

You're both saying my (15 year-old ! ! )vac lines might be cracked?!?! ;-)
Yeah, sounds like a roll of hose & some quality hood-time is in order, even if it doesn't fix the problem.
-------
I had the AC dye-tested at a local shop that I've had good results with, so I'm reasonably certain that their diagnosis is correct. Don't recall seeing any goop from a leak on the compressor.

Results early next week, thanks!

 

rtk3:
15 yr old vacuum lines cracked?....it is a remote possibility.......

 

FOUND IT - hoses were in surprisingly decent condition, swapped the easy ones anyway. Just for the heck of it, I dropped the covers under the dash to see what I could see. The color coded vinyl (?) hoses were all fine; just above the go pedal are two door actuators. the one that operates the defroster door mounts horizontally on a plastic fork. Apparently, over time the detent that holds this actuator in place wears out & the actuator slides off the bracket, so it just hangs there going up & down w/o moving the door. Re-asembly and a small, carefully placed screw (NOT into the cylindrical actuator housing!) will hold the motor in place.
'Preciate the responses & help!
rtk3