Oh yes this job is a treat. You will be surprised what you can break. Why do you want to replace the temp sensor? Never saw on go bad. Even if the controller went bad splice the replacement to the sensor itself. To clean the rear of the evaporator use compressed air with a long thin tube. 

If you must drop the housing you need to beginning be removing all the ductwork beginning from the front and working back. Then support the rear works in a way you can lower gently. You will need to carefully disconnect the side drain tubes. It is easy to crack the drain pan where those hoses connect. Once down you get to separate the top cover which is glued or plastic welded in place. Once inside you will find the foam is likely disintegrated. Part of the job of this foam is to keep the condensed water from spraying off the evaporator and into the vents. Replace it. Then the challenge is getting it back in place. A helper is real handy for this one. 

Dennis

-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of Dan N
Sent: Thursday, November 13, 2014 9:54 PM
To: vanagon@GERRY.VANAGON.COM
Subject: Removing the rear AC top cover

hi all,

'90 Carat... I want to remove the rear top plastic cover of the AC evaporator... to clean it and replace the temp sensor...

I removed the side panels, the rear plastic screws...and there's the 4 bolts on each side...

now if I remove the last 4 bolts on each side... will the condenser and everything will crash down..? should I put something to hold it before removing the last 4 bolts?

thanks in advance

dan