Okay, wish me luck, everybody; I'm using my vacation days to _finally_ (after too many years) get the leaky old evaporator out of the firewall, get a new one in there and get some working A/C once again. As I type this I've got most of the components out of the way and am going in after lunch to get the evaporator/core housing cover off.

Got the factory manuals to guide me on this, and it'* been not-too-bad so far. System had basically nothing left to evacuate; pushed on the low-side Schrader valve anyway just to see if anything would come out, and got nothing but some hot air.

Fittings for A/C accumulator unscrewed nicely without needing the dreaded Special Tool for disconnecting in-line connectors, and accumulator lifted right out. Wrapped it in a plastic shopping bag to keep it clean for now. Also wrapped plastic bags around open A/C lines to keep dirt out of condensor and elsewhere.

Discovered that the vacuum reservoir on the Bonneville is _not_ the usual black spherical thingy seen on older cars, but is a large _cube-shaped_ plastic box on the firewall right next to the brake booster. Wonder how much wrong advice I've been giving out about _that_ thing here, thinking of what the one in my old '82 Cutlass looked like. My bad. :(

Discovered in the course of removing the blower motor that its cooling duct is completely missing, so there'* been a nice 1" diameter hole in the housing, letting engine-compartment air right into the ventilation system all these years. Charming. Also found that the blower speed controller (goes in the same hole as the blower resistor pack on manual-control cars) was held in by 3 different 7mm screws, only one of which looked original, which makes me suspect that some goofball'* had this stuff apart before. (Some months ago when I was installing the remote starter, I found an entire pack of Kool cigarettes with a 1994 tax stamp jammed inside the dashboard.)

Got the underhood fuse/relay assembly detached now, and after figuring out how to release the three big relays on the passenger'* side of the holder, I was able to detach the right and left wiring harnesses into two halves, and swing them completely out of the way.

Can now see the entire top of the housing that needs to come out. Next step is to detach the lower heat shield and some underdash pieces (including the ABS controller, I think) to get at a couple of bolts on the inside, which should release the housing to let me get the evaporator out.

Haven't ordered the new one yet; figured I'd wait to make sure that the old one is leaky and covered with dirty oil and dust, like I'm told I should find when I get it extracted. The local Lee Auto outlet has a new GM replacement available for next-day order, so let'* see if I can get the order in by end of today.

Will check back in here periodically later on, so if anyone'* got any helpful tips for swapping the evaporator, let me know...

Are you going to recharge the A/C yourself?

Hang on a second; I need to stand on this chair...

HEY EVERYBODY! THE EVAPORATOR CORE IS OUT!!!!

WooHoo! I am _totally_ happy right now...

It turns out that it _has_ been opened up before, and a mystery has just been solved, too. See below...

I took off the lower heat shield and the big 10mm bolts around the top and sides of the core housing. The lower left one was missing. Hmmm. Discovered that the outer cover is actually two pieces: the black outer part is a flexible rubber cover with insulation blankets inside, underneath of which is a sheet metal outer housing. I pulled the rubber cover off without much trouble, and got the sheet metal housing off after locating two 7mm screws holding it to the firewall. Noticed that the rubber cover has a molding date on it of January 6, 1993, which fits with the car'* February, 1993 final assembly date. It had also been cut along its lower edge, another tipoff that someone had been working here in the past.

After the sheet metal cover came off, the evaporator core was free to lift out. Took a bit of twisting and turning but I was finally able to clear everything without bending stuff, so the new one should go in without scraping anywhere. Here'* where it got _real_ interesting.

The evaporator has an ink-stamped date code on it of "278 94", which I'm pretty sure indicates a production date of the 278th day of 1994, which would be the same year as the tax stamp on the mystery pack of Kool cigarettes that I'd found inside the dash ducts earlier.

The core also carried a large sticker saying that the EVAPORATOR CORE WATER SEPARATION SCREEN MUST BE REMOVED FROM ORIGINAL CORE. IF IT IS NOT AVAILABLE, A NEW ONE MUST BE ORDERED. So of course I can't see anything resembling that, and the manual doesn't mention it either, so I don't know if I'm going to be able to get a new one. Will ask the Lee Auto guys to check their book on that (unless someone here can tell me what that thing does).

But here'* the best part: the core _had_ sprung a leak exactly as advertised, and the leak had gotten the core completely wet with oil on the outside, and normal airflow had eventually packed the whole outside of the core with gooey crud. Fully half of the core is completely covered and blocked off; no wonder I couldn't get any airflow in the car! And with all due respect to the TechInfo article on spraying brake cleaner through the resistor pack hole to clean the core, the only area that can be reached by that method was in fact the only area still clean anyway. Fortunately there was still enough airflow there to prevent the electronic blower control from burning up.

So now I'm off to order the new core and see if I can't get my hands on it by tomorrow. Once I get everything back together, I'm going to have a local place draw the system down and make sure it holds a vacuum. Say, what was your question again?

Well... I'm tempted to just do a closed conversion to R134a if everything else looks good. OTOH, if everything else _is_ shipshape, I might just splurge on 3 lbs. of Freon Classic, and have a local shop put it in. I've got an R134a conversion kit from Interdynamics here so I have the option of going with R134a, too. (The '96 Trans Sport just needed a little topping off, but I bought the conversion kit anyway because it came with a gen-you-whine low-side charge pressure gauge, 3 15-oz. cans of R134a with oil, and a set of conversion collars for the valves.) What do you think?

I'd stick with good 'ol freon if I had the choice. Do the 134 swap only when absolutely necessary.

Great detective work, btw.

Yeah, that'* going to be my first angle. If I get some lunatic estimate, I might shop around or go with R134a, but if everything else in the system is still good and solid, I think I'll feel better getting the original stuff back in. It'* what the electronic climate-control system expects to be working with anyway (not that it would notice, but still...).

Thanks! I'm still kind of irritated at the bozo (probably from the dealership) who did the hurry-up core replacement last time, but at least he spared me the trouble of having to disconnect the lower bolts that (according to the manual) release from under the dash. I wonder if he still wants his cigarettes back...

Okay, Lee Auto sez they'll have it delivered overnight, ready @ 8:00 a.m. tomorrow. Cost about $150.00 and change; AC-Delco part. (I assume it'* actually a Harrison manufacture if it'* really original equipment; will see what'* in the box.) They also had a Four Seasons brand for about $10-$15 more, but I've had too many bad experiences trying to get aftermarket cores to line up with the car connections, and if you've ever seen the plumbing coming out of a Bonneville evap core... they're twisted around like a pretzel. Taking the old one with me tomorrow morning, and I'm not leaving the store with the new one unless it'* identical.

No one had any clue about the WATER SEPARATION thing that the warning label was screaming about on the old core, so will just have to see what AC-Delco puts in the box with the new core. A little compressor oil for the O rings would be nice, too. (Any other kind of light oil I can use if I need to? WD-40?)

As for the missing cooling duct that'* supposed to be on the blower motor, I had no joy looking for the thing in the Motormite "HELP!" line at two Auto Zones so far, but I could swear I've seen it in their line of parts. Forgot to check for that at Lee; will try there tomorrow morning. I figure at worst I can stick it on later; should be able to reach down there even when everything else is reinstalled.

Gotta get a good start on this tomorrow; I'm wiped. Really want to get it all reassembled tomorrow if possible; I hate having cars in pieces all over my garage... (okay, I know, my K wagon sat that way for 17 months with the cylinder head sitting on a block of wood, but I've reformed, really, and hey, it _did_ run once I put it all back together, too...) Goodnight everybody...

I would stick with the R-12. Easier said than done. That stuff is costly. I have a bunch of R-12 sitting around that I use. I've only replaced 12 oz in my car.

The airflow in my car feels so-so. I don't know if it is due to a clogged evaporator or if it is normal. The vent on the far right side has low airflow compared to the rest of them. Is that the side most affected by a clogged evaporator?

Lucky you. I'll be starting from an empty system, so I'll need... what? 2.4 lbs.? Something like that... I do have the sticker with the exact numbers on it, anyhow. I've also got an unopened 1-lb. can of Interdynamics R-12 in one of those old do-it-yourself refill kits, complete with tapper hose and everything, but that by itself isn't enough Freon to do the job, so I think I'll leave it alone (or maybe sell it on eBay; what are they selling for these days? )...

No, I don't _think_ the clog would affect one side more than the other, because the air has to go through all kinds of twisty ducts before distribution anyway.

I do know that the air would always come pouring out of the vent to the left of the glovebox whenever somebody opened the lid, so those little adjustable vents must put up some real resistance of their own. Once I get everything buttoned up again I'll be able to say for sure. Was relieved to see that the heater core was nice and clean, too.

2.42 pounds. Don't forget that some of the compressor oil also leaks out with the refrigerant. You may want to also replace some of the oil with 525 viscosity mineral oil.

r-12 is legal were you guys are? I still have some cans, but its ilegal to sell where I live