I have a 1998 Ford Escort with 113k miles. It's never given me any major problems before, except for the AC going out about 4 months ago (details to follow).
In the past week while driving with the AC on, I've noticed that the cold air stops blowing and becomes lukewarm. At the same time, I noticed that my engine temperature gauge is in the red. I took it to a reputable mechanic, they did an engine head test and a coolant pressure test, saw no issues, and couldn't reproduce the problem.
The problem has kept happening. Generally, I am driving at highway speeds with no problem. If I encounter traffic below 30mph, or switch to city driving, the car begins to overheat. If I notice the gauge in time, I can turn off the AC and sometimes it will return to a normal temp. (Though sometimes it will overheat even if the AC has not ever been on.) The car overheats to the degree that steam begins coming from under the hood in the vicinity of the coolant reservoir.
Back to the AC, when it broke a few months ago it was diagnosed as a bad relay in the CCRM. I replaced the original CCRM with a remanufactured one (made by BWD) from Advance Auto Parts. I'm wondering if this could have something to do with my current problem, since I think the CCRM does much more than run the AC.
Any advice is appreciated.