As my contribution to this helpful thread, here are some pointers I donít recall seeing and wish Iíd known before I started.
1. When removing the front clam, do your best to capture the shims on the two bolts that fasten the clam to the quarter panel in front of the door (BEFORE YOU PULL THE CLAM LOOSE), so they can go back exactly the way they went in or, worse, so you donít have to remove the quarter panel when some shims fall inside of it. Leave the back screw in place, just loose, as it is almost impossible to get it started in the tight confines adjacent to the hinge.
2. This web site (mentioned above, too) has helpful steps and photos Resistor pack - TechWiki
3. I built a replacement resistor set (and got the resistors on Amazon for about $20!) on a piece of sheet aluminum much like pictured in the posts above, and I bolted that sheet to a thread-sert already in the chassis (near and below the fuse box) so that the sheet and chassis could serve as an ample heat sink. I was not a fan of putting them in the HVAC airflow as the A/C is already a bit anemic in Texas heat. I tested this and on the medium setting, my infrared pyrometer showed them getting up to about 180 deg F. I doubt that will hurt them, but do make sure they touch nothing else.
4. Attach a string securely to the evaporator box plastic drain hose (it sticks out just behind the lower front control arm) because it is likely to get pulled into the chassis when you remove the box with evaporator and heater core. Also, donít forget to re-attach this drain hose to the bottom of the evap/heater core box when you reinstall it. Then use your string to incrementally pull the hose back into place as you lower the box, so there will be no kinks in the hose and the condensation will properly drain from the box.
5. Do not have small children around when re-installing the box and fan assembly unless you have never sworn in your life Ė and you still may utter a few epithets in this rubikís cube process, especially if you forgot to reconnect the hose in 4 above and have to take the *&*#@@$ thing back out again.
6. I put new putty around all of the refrigerant and other lines coming into the box before reinstalling it.
7. I used a funnel and hose to pre-fill the heater core before re-attaching the heater hoses in the hope that would simplify cooling system bleed. I think it helped.
8. Read the Lotus A/C section from the official service manual as it has key info on how everything works, o-ring sizes (replace them on the lines you separate), type and amount of refrigerant and refrigerant oil. You should really not be DIY-ing on this car without this manual!
9. I found it hard to precisely measure the amount of R134a added (e.g. hoses are connected to the can when charging, affecting the perceive tare), so I also checked pressures and outlet temp. I saw a high side pressure of about 260 psi and outlet temp of 55 deg F with ambient temp about 82 deg F and the top off and doors open and based on this and the amount of R134a I seemed to have fed, called it good. Low side pressure was nice and low, I canít recall now but something like 30 psi, so I considered the system at least not overcharged.
10. I donít know about you, but I had a bumper crop of dead bugs and leaves in all kinds of nooks and crannies, so look around carefully and vacuum that detritus now as you canít get to it later.
11. Get everything in the HVAC system up and running before reinstalling the clam, including testing the fan speeds, how hot your resistor pack gets, whether the door between the evaporator core and heater core cycles (the stepper motor wires are pretty fragile and could be damaged when wedging the damned box back in place), and if time permits wait a day to be sure you have no refrigerant leaks before the clam reinstall.