A/C problem, and more pinging
I'm on my second T-Bird now. The first one had a problem where the A/C would switch from panel to defrost whenever the engine was under mild load in a high gear, such as accelerating away from a stop sign at a leisurely pace. I thought that it might be low vaccum, but I never noticed any other problems that would indicate a lean condition.
Now, my new Thunderbird does exactly the same thing, only a little but worse. The difference is, this one runs WAY hotter than the old one, and the engine pings between 3800 and 5000 RPM. Whereas the old car hardly ever got up to the "N" on the temperature gauge, this one easily pegs it out if the engine is run at high RPM for very long. Cruising down the highway, the temp guage is normally about an eighth inch past the M, on the hot side. What's going on here?
The car has about 80,000 miles on it, and it was owned my a 50-60 year old school teacher when I bought it. Is this something that can be fixed, or is it just messed up from being driven short distances by an old woman for most of it's life?