Q: iMac will not go to sleep

Maybe this helps you

Re: How to stop AddressBookSourceSync

Please quit the Contacts or Address Book application if it's running.

Triple-click anywhere in the line of text below on this page to select it:

~/Library/Caches/com.apple.AddressBookSourceSync

Right-click or control-click the highlighted line and select

          Services ▹ Reveal in Finder (or just Reveal)

from the contextual menu.* A folder should open with an item selected. Move the selected item to the Trash.

Log out or restart the computer and empty the Trash. Test.

If your Mac doesn't sleep or wake when expected - Apple Support

Reset the System Management Controller (SMC) on your Mac - Apple Support

Check your Energy Saver settings to make sure they are correct.

Please test after taking each of the following steps that you haven’t already tried:

Step 1

Take all the applicable steps suggested in this support article, including the ones under the heading "If the previous steps don't work." That's the starting point for any further effort to solve the problem.

Note that, as stated in the article, the computer will not sleep if some sharing services are enabled. From the menu bar, select

           ▹ System Preferences... ▹ Sharing

Turn off all sharing services.

Also note that the "external devices" referred to in the article could include Bluetooth devices, other than those made by Apple. If you're using a MacBook, MacBook Air, or MacBook Pro, or if you're using a desktop Mac with a wired keyboard and mouse, turn Bluetooth off to test.

Step 2

If iTunes Music Sharing or Home Sharing is enabled, disable it or quit iTunes. Do the same with any third-party applications that have a similar feature.

Step 3

Select

           ▹ System Preferences... ▹ Accessibility ▹ Speakable Items: Off

Step 4

Select

           ▹ System Preferences... ▹ Bluetooth ▹ Advanced...

and uncheck both boxes marked

          Open Bluetooth Setup Assistant at startup if...

Step 5

Reset the printing system.

Step 6

Back up all data.

Triple-click the line below on this page to select it, then copy the text to the Clipboard by pressing the key combination  command-C:

/var/vm

In the Finder, select

          Go ▹ Go to Folder...

from the menu bar and paste into the box that opens by pressing command-V. You may not see what you pasted because a line break is included. Press return.

A folder named "vm" should open. Inside it, there may be a file named "sleepimage". Move that file, and only that one, to the Trash, but don't empty yet. You'll be prompted for your password. Close the folder window.

Restart the computer and empty the Trash.

If you have AppleCare, give them a call & let them deal w/it. 

As a desktop (iMac) owner, you may qualify for "on site" service instead of having to lug your iMac to the repair shop.  You will need to call Apple Care to confirm.  Ask to speak to a supervisor and/or Sr. Manager.

This procedure is a diagnostic test. It makes no changes to your data.

Please triple-click anywhere in the line below on this page to select it:

pmset -g assertions | pbcopy

Copy the selected text to the Clipboard by pressing the key combination command-C.

Launch the built-in Terminal application in any one of the following ways:

☞ Enter the first few letters of its name into a Spotlight search. Select it in the results (it should be at the top.)

☞ In the Finder, select Go ▹ Utilities from the menu bar, or press the key combination shift-command-U. The application is in the folder that opens.

☞ Open LaunchPad and start typing the name.

Paste into the Terminal window by pressing the key combination command-V. I've tested these instructions only with the Safari web browser. If you use another browser, you may have to press the return key after pasting.

Wait for a new line ending in a dollar sign ($) to appear below what you entered.

The output of the command will be automatically copied to the Clipboard. If the command produced no output, the Clipboard will be empty. Paste into a reply to this message.

The Terminal window doesn't show the output. Please don't copy anything from there.

What happened when you tested in safe mode?

Hi Linc,

I have seen your support and wondered if you were willing to review a support request I have here: iMac becomes slow constantly if you have time.

Thanks so much,

David