How can I fix my iMac audio not playing through speakers?

This is a problem that plagued early (2006-~2008) Macbook Pros and is, as den.thed suggests, likely a stuck "mute switch" contact inside the jack.

Apple's audio ports are quite well engineered. The problem is that 3.5mm audio plugs are not. If the plugs' dimensions are just a little off, they can jam the mute switch in the "I have headphones" position, causing the symptoms you see and don't hear.

Brand has nothing to do with it. I have a set of headphones from a maker of quality audio products who 3.5mm plug is just too long in the tip. This is how I must position that plug in an older Macbook Pro to prevent jamming:

Note that it is not fully inserted, It's likely you've encountered the same thing. The crazy part is that I have a no-name set of external speakers I found at a yard sale for $1 whose plug works perfectly when seated "to the hilt."

On old Macbook Pros, you could look into the audio jack and see a dim red light glowing if the mute switch were jammed. I've not tried that on an iMac because my last two never jammed. Still, easy enough to check.

There may be a fix that does not require take-apart. Insert a headphone plug and CAREFULLY move the plug slightly from side/side and up/down. Sometimes that is enough to unstick the mute switch.

Sounds like the micro switch inside of the headphone port is stuck in the External Output position.

Or.... there is a broken off tip from a headphone jack inside of the External Output Port.

In either case, the iMac's Headphone Port needs to be serviced by an Apple Authorized Service Provider.

One work around that might work for you, is to create a Multi-Output Devices using the Audio MIDI Setup that includes both Internal Speakers and the External Headphone output at the same time.

Restart the computer in Safe Mode, please click Safe Mode to learn how. Then restart normally and test.

Then it is time to follow den.thed’s advice, take it to your local Apple Authorized Service Provider to be serviced.

iMac speakers not working? Try these easy steps:

1. Check the volume—make sure it is turned up and not muted.
2. Choose the right sound output—go to System Settings > Sound > Output and select Internal Speakers.
3. Unplug devices—remove headphones, USB gadgets, or turn off Bluetooth.
4. Restart your iMac—a quick reboot can fix small issues.
5. Update your system—open System Settings > General > Software Update and install if something is available.
6. Reset NVRAM—shut down, power it back on, then hold Option + Command + P + R for 20 seconds.

Kamalnath.R

[Edited by Moderator]