I need to check to see if my hood has that front seal. Pretty sure it does, but I can't recall. Can't do it on a whim, since I keep my car at a storage unit so I'll check tomorrow. I know it has the cowl seals because I have photos showing them.
Also, Brian, when I put in my Cold Case radiator, which is at least as thick as the stock HD cooling copper/brass rad, there was still a slight gap between the radiator and the fan shroud, and my fan shroud is the correct one for my 400 engine. This tells me that there was probably a slight gap there even from the factory. Still, I sealed it up with some generic weatherstripping to fill up the space, but it's more of a satisfaction thing since I don't think it's made any profound difference in cooling at idle or low speeds.
You and I have the same issue. My car will run at or even below thermostat temp (I use a 160) till' the cows come home at idle or driving around without AC, but if I turn the AC on, the temp starts to climb, especially at idle. I've never let it get too high to see how high it will go, but it does heat up relatively quickly. I wouldn't mind it so much if I could actually see it stop increasing temp, even if it it's at 190 or 200, but it just continues to climb even past those numbers. I'm starting to think it's more just inefficiency with the compressor, insufficient charge, worn out AC components (compressor is new and system is converted to R134a; but the evap core and condenser are still original), or the compressor overstressing the engine maybe because it's binding or something. It's a newer A6 compressor but not a particularly high quality one - probably some cheapo reman. Also, Florida will put any AC and cooling system to the test - on a hot day, my compressor just stays running and running, I've never let it go long enough to see it eventually equalize pressure and exchange the heat out of the cabin in order to cycle off (if it can even do that on a hot day), because by then I feel the engine temp will be ridiculously high, so I don't risk it. As for the AC performance, it does blow cold - not freezing cold, but it does *work,* and like you it works better at speed vs. at idle. Is your AC idle solenoid working, too? You need to compensate for the compressor load on the engine, or else that reduced idle and increased engine load will add heat to the engine for sure.
I did notice that if I try to accelerate hard with the AC on, the car bogs and falls flat on its face a lot more easily than the occasional Quadrabog we are used to with Q-Jet carbs. I'm starting to wonder if the heavy duty fan clutch is playing a small role in this, as it puts more of a strain on the engine, and combined with the compressor it is really stressing the motor. Even AC cars from the factory didn't come with a heavy duty clutch, they just came with the standard duty which is a lot gentler on the belt drive.
