[Yesterday (Saturday): 4.5 miles on Pat Station Loop with Bill’s Cutoff ]
We had the running club Christmas Breakfast yesterday and I went over to Starkville for that. It was a cool morning, has been all week with temps in higher 20’s early in the morning. That is pretty cold for Mississippi.
I enjoyed that run and the group thing. Then I came home and puttered around.
One thing I did was work on the A/C for the radio station. I took the front and cover off of the “broken” unit which was left with me to be disposed.
The control module was separate from the front panel and it had some very nice labeling of connections. From that I was easily able to figure out which of the 4? 5? temperature sensors was for outdoor ambient air temp. It was colored yellow too, that helped.
I unplugged that and measured the resistance of the sensor indoors (75-ish degrees – 5.6 KOhms) and dipped into the chest freezer (6.x KOhms) and that established that the thing did just indicate by resistance and that the number I want is 5.6-ish or maybe a bit less. I want it to think it is 70-80 degrees outside all the time.
I dug through my stuff and found a nice little 5.7 KOhm resistor (one of the standard available values) and crimped on a couple of bits to let me slip it right on to the connector.
I stuffed the disconnected real sensor into the box out of the way so I could reverse the modification later if I want.
And that seems to have done the trick. Here is the temperature plot. You can see that the unit was not working (too cold outside) in the early morning, then the internal temp rose with over the course of the day, then I did my thing swapping the unit with the door open, then it went into that beautiful horizontal-going zig-zag that we love so much.

The temperature in the late part of the day would have traversed that same no-run region, so the fact that it ran steady all night is a sure indication that it no longer is limited from running. Success!
I probably should have made a video of what I did and posted it on YouTube. But by the time I thought of it I had already gotten it all buttoned up. I could shoot the video on the 2nd unit… that one is now sitting in the garage. Maybe I will do that some day.
One reply on “A/C success”
You fixed it! Go Dad!