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Phil, Mechanical Engineer
Category: HVAC
Satisfied Customers: 6022
Experience:  Retired HVAC/ Electrical & Boiler contractor. Industrial
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My AC wont turn off. Its a Coleman Presidential Evcon, from around 199

Customer Question

My AC wont turn off. Its a Coleman Presidential Evcon, from around 1992. Air is cold, strong flow through vents. Tried a new thermostat, yes thermostat is getting power. Changed a relay...still wont shut down. Will shut down manually at switch on unit.
Submitted: 2 years ago.
Category: HVAC
Expert:  Phil replied 2 years ago.
Hello, If you can send me a clear, well focused, close up photo of the wiring diagram glued inside the blower cover door on your furnace or air handler, and a photo of the printed circuit card that shows where the thermostat wires connect I can help you by marking it up with trouble shooting instructions.Use the paper clip icon above to attach those. Tell me please if the outside unit runs in the winter for heating as well as in the summer for cooling or not. We can go from there.
Customer: replied 2 years ago.
I will be at the house within an hour and will get those images to you. The outside unit does not run in the winter. Something else to add...for about 3 months there was a buzzing sound from the unit each time it kicked on or off. Got progressively worse. The buzzing sound seemed to be coming from the control panel on the interior unit. That is when I was advised to change the relay.
Customer: replied 2 years ago.
Phone wont upload images. Will upload from computer this evening
Expert:  Phil replied 2 years ago.
That will work.
Customer: replied 2 years ago.
Let me know if these are not clear enough, I can sketch the diagram if needed. The relay to he left is the one I changed out.
Expert:  Phil replied 2 years ago.
Hello again, thanks for trying.
Do not draw those by hand, there is too much room for error, instead carry a lamp to the area so the pictures are well lit enough to read.
put the lamp behind you, with your shadow out of the way, and take the pictures that way.
If you take a close up picture of the wiring itself and relays so close that I can only see a part of some of the wiring, its too close to put anything in context.
I need the same sort of pictures taken of the outside unit including its wiring diagram.
Your thermostat picture shows that it is wired for heat only at the thermostat at least. Send me the pictures and I will see what I can do.