Alrighty, I've got my car half apart and wanted some advice. I have a 97 Bonneville, SE and the evaporator in the A/C system is leaking. Haven't seen many detailed posts on this topic. I am trying to get at the evaporator from the engine/firewall side by removing the large plastic covering where the blower motor is. Not much fun, i've removed about 15 bolts and still can't get it out. I'm now crawling under the car to locate additional bolts. Here are my questions:

1. Wondering if I can get to this thing from under the dash? Is one method preferable?
2. Thinking about changing the heater core at the same time, I'm assuming that once I'm in, I might as well change everything. Anything else I should consider?
3. On the firewall plastic cover, there is a line and it says cut here to remove. Should I really, or just remove all the screws and go for it? Seems like it wouldn't be that much harder to take the whole thing out. I just hate cutting something out of my car.

Thanks in advance. These boards are fabulous.

Lance

Bump.

Anyone with experience with this?

I haven't done it but will look in my FSMs tonight in case nobody else chimes in.

From what I remember from previous threads, you need to pull the entire dashboard out, then remove the HVAC case, then remove the evaporator. Don't quote me on this, I could be (and probably am) COMPLETLY wrong, but it seems to stick in my mind as being a real P.I.T.A. to replace.

For 1998 model

Remove refrigerant
Remove cross car support brace
Remove fuse block cover (In engine compartment)
Remove the accumulator
Remove the Positve booster cable from the multiuse relay center
Position the underhood fuse block out of the way
Remove the evpaorator tube from the evaporator
Remove the Wire hardness clip from the HVAC module
Remove the heat shield of the HVAC module
Following the cut lline, cut the top side of the HVAC module cover
Raise and support the Vhciel
Folliwng hte cut line, cut the bottom side of the HVAC module cover
Lower the vehicle
Remove the fuel line clip from the HVAC module
Remove the insulator from the module
Remove the bolt tha ttaches trhe heater and A/C module assembly to the inside of the vehicle
Remove the blower module from the HVAC module assembly
Remove the evaporator core

Thanks imidazol! Right out of the book, LOL!

I just got to my '97 FSM and the procedure is the same there.

Bottom line, Lance, is that YES, you do have to cut the insulator and get at the evap. from the engine compartment.

If you were planning to replace the heater core at the same time, it makes some sense to do it now, as this is certainly a PITA operation and not one you want to do very often, IMO.

Also, it should go wothout saying that you should disconnect your battery cable and properly evacuate and recycle your refrigerant prior to opening the A/C system.

Wow..can't believe i didn't see this before.

Yes you must cut. Here are some pics as to what you would see if the motor was out.
The evap core in the 97 ready to come out


Interesting shot of the heater core and how the air mix door when opened allows air to flow through it.

Well, the procedure is complete and yes all the above is a PITA. But, it was going to cost me $850 for the shop to replace just the evaporator and I replaced all the following for less than $400:

Evaporator
Heater Core + 2 hoses
Heater Blower Motor
O2 Sensor
6 Spark Plugs
Wire set

I plan to fire it up tonight. While on the topic, I now have to recharge the AC system. I thought I saw that I need to use a vacuum pump to get the air out before charging. Any thoughts on this? I'm going to go to AutoZone and see if they have a loaner for this.

Just for reference, cutting the cover is not required, but it makes it a whole lot easier. To not cut the cover, you must remove all the heater core hoses which is another headache in a bottle.

One other tip, I did not have to remove the dashboard to get the heater core out, but I did have to loosen a whole bunch of nuts, bolts and screws to get the heater box loose enough to manuever the heater core out of the box. I'm really glad I didn't have to remove the dash. For those replacing the Core, there are two bolts at the bottom of the heater box that attach it to the firewall right where your toes are when sitting in the passenger side. I had to pull my carpet back to find one of them it was hidden really well. Then you need to be a contortionist to get to the second heater box screw up top (behind the glove box) and your in.

I'll share more once I get everything recharged.

Lance

Lance...on the heater hoses, there is a tool for hose clamp removal that I found at Sears. Worth every penny when trying to get the clamps behind the strut tower.

Thanks for the follow-up, Lance.

And Yes, you DO have to draw a vacuum before and while charging the system. Additionally, you should always replace the Accumulator assembly too. Especially after the system has been open to the outside air for so long. The Accumulator contains a dessicant that drys out the system and keeps water from getting into the compressor.

Water in the compressor can "slug" the compressor as water does not compress. So, spend the extra bucks and replace that Accumulator assembly. Otherwise all that work will have been for naught.

I don't know if you can borrow or rent a vacuum pump, but some decent A/C shops will recharge your system for a reasonable price. You get the added benefit of their leak testing equipment too.

Let us know how it turns out.