After getting the radiator and all subsequent leaks stopped it was time to move on to the evaporator core. I destroyed the threads on the old one when I was trying to install the AC dryer. On these cars you remove the top half of the air box and the evaporator just sits inside. These boxes are very easy to break or crack as they get older and there is a urethane material that seals the two pieces, so it can also be easy to damage the pieces when attempting to pry them apart. I got mine apart without further damage than had already been done by the individuals that had worked on it previously. I also found that the last person to install the orifice tube had put it in backwards. One small silver lining is I was able to thoroughly clean the air channels while I had this apart.
This is what the area looks like with the top removed. I used a putty knife to help separate the two halves. The evaporator sits inside a cradle with no mounts, only soft strips to insulate it from vibration.
After the evaporator was out I had to scrape all of the old sealant off of all of the mating surfaces. The worst part about this was that I had already sealed the top and side of this box to the cowl when the fender was off. These areas are very prone to leak on these cars and I used windshield sealant to seal the area the first time, as was shown much earlier during this LS swap project. Now I had to re-seal it again, but this time with the fender on, so it was more difficult. I took a vacuum and cleaned the the bottom of the air box, then wiped it down with wet towels. I had never had this off of one of these cars so it was interesting to see in person, not just a drawing, how the hot and cold air is directed through the car.
The sealant had dried so I tried to poke down until I made an exit, but the bottom of the tube was apparently dried too and the caulk gun wouldn't budge. I had to cut the tube with a hacksaw to get to some of the usable middle parts. I used windshield adhesive strips to seal between the upper and lower part of the air box, which worked great but I wasn't thinking and put them on the upper side of the box. It is a tight fit and I couldn't get the box installed without messing up the sealant, which of course should have been obvious to start with. I ended up having to remove all of it and then install it on the bottom part of the box and then sit the top down on it. This, the correct way, worked much better.
After getting the evaporator back in I installed the AC dryer. After getting that on I moved on to the final piece of the AC system that I'll have to make, since I'm going to have the remaining two hoses made at a hydraulic hose shop. This is where I did something very stupid. Because I had ruined the old AC dryer I had to order another one and I had to piece together parts from various different vehicles to get it all to work. Also, it's been several months since I had worked on the AC wiring. I knew that I had cut the end of the low pressure switch off of the original harness but I couldn't find it anywhere. I had the new low pressure switch that I was going to be using and I remember that I had test fit it and it worked but I couldn't find the end I had cut from the original harness anywhere. I tend to keep things of like manner together so I don't have problems finding them later on, but I still could not find this thing and I ended up spending several hours over a couple days cleaning out and searching through my garage. I finally realized that I was trying to find something that didn't exist. For some reason throughout this process I had ended up with a new R12 low pressure switch, which has a very large plug in the end for the harness and that is what I was trying to find. I finally realized that the R134A low pressure switch is the one that I had finally determined I was going to use and one of the pigtails I had in the box fit it perfectly. I had a couple different pigtails because the place I ordered it from (Summit I think) had an issue with their computer system saying a few different part numbers fit the same application, depending on how you looked it up. They ended up sending me more than one and told me to keep the ones that didn't fit. After I finally remembered all of that and remembered which new pieces were right and which new pieces were wrong I finally realized I'd had them in front of me the whole time.
I then found another issue. The low pressure switch is just a ground from the PCM with a switch in the middle. The pigtail from the switch has two wires so I expected to find two wires in the harness that I had put aside, but I found that there was only one wire there when I un-taped everything. In short it turns out this is because I was combining multiple types of AC systems in order to get the computer to be able to control the AC system. The issue stemmed from the fact that the original compressor had a ground wire coming off of it, which the low pressure switch would tie into.
My compressor doesn't have a ground wire because it grounds through the case and mount. It only has one wire coming from it.
I could have spliced the ground wire into the existing hardness somewhere, but there were a couple of reasons I opted not to do this. To access the back of the harness for soldering I would have had to remove a large portion of it from the car, which would have taken a long time. Also, just finding a ground and splicing in this ground could cause issues with having two pieces of harness now tied together that later I would wish weren't permanently together. I opted to run a dedicated ground and attach it to the back of the passenger side cylinder head where the other grounds from the harness attach.
Then I soldered in the other end of the low pressure switch pigtail with the existing wire from the engine harness.
Below you can see the new ring terminal for the ground. This ground bolt is somewhat difficult to remove and install because the transmission dipstick is so close to the bolt.
Here is what the finished product looks like. After getting all the wires in a loom and taped up with black tape all I need now is a hose made to run from the AC drier to the compressor and one from the compressor to the condenser and I should have AC, which is good because some days are starting to get hot, which is OK with me, but the wind can be a bit much for two young girls with long hair sitting in the backs seats.
When I went to move the car after getting everything put back together I noticed the pedal felt weak and the brake light was on. I checked the master cylinder and found that the rear pot was empty, so I suppose the next step will be finding the leak which will most likely mean new wheel cylinders and hoses for the rear.
