I have searched through many postings here and on other Jag slave sites and I think I have narrowed my problem of my '83 XJS. My climate control is wonky. I, like others, will be enjoying cool air conditioning on a nice summer day and then the servos start doing their thing and then I have hot air roasting my feet. The opposite occasionally occurs but only rarely. Staying in the A/C mode is the biggest challenge. I've checked all the vacuum lines and they are all intact. The servos are directing the air and shutting off the hot coolant flow in a very coordinated manner, just at the wrong times. I never get air out of the foot and center vents at the same time or any other combination to suggest a servo problem. From my research I think that the amplifier is the most likely culprit, with the temperature sensors being a distant second. I did confirm that the under lip air sensor intake by the glove box was still hooked up and the wires were attached. I actually went through the nut roll of removing the amplifier, the placement of which had to have been designed by a sadistic psychiatrist and a contortionist as part of a test to assess dexterity, ingenuity, and patience in patients with OCD. I'm not sure I'll be able to get it all back together but it's out now.
Does anyone know of a way to test the unit to conclusively determine if it is the actual problem? If I had another XJS I would just do a plug and play without a complete installation, but I would have to do it on the side of the road because my wife would likely kick me out of the house if I purchased another one.
I attached a picture of my amplifier only because I have a fragile ego and I think that removing the unit without resorting to taking a hammer to the vehicle is a noteworthy feat.