iMac 21.5-inch (2015) — How to Replace the HDD with a 2.5″ SSD

Time: 60–90 minutes
Difficulty: Intermediate
Models: iMac 21.5″ (Late 2015) A1418 (EMC 2833)
Goal: Swap the slow 5400rpm hard drive for a fast 2.5″ SATA SSD.

⚠️ Important: Opening 2012–2019 slim iMacs requires cutting the display adhesive. Work slowly, support the panel at all times, and replace the adhesive with new strips. If you’re not comfortable, have a technician do the install.

What you’ll need

• 2.5″ SATA SSD (e.g., 500 GB–2 TB).
• Adhesive strips for iMac 21.5″ (2012–2019).
• Torx drivers: T5, T8, T10.
• Plastic opening wheel / adhesive cutting tool (or a thin plastic card).
• Spudger / plastic pry tool, tweezers, ESD strap (recommended).
• Optional: 2.5″ drive bracket/spacer (many kits include it).
• Isopropyl alcohol and lint-free wipes (for removing old adhesive).

Note: 2012+ iMacs do not need an inline thermal sensor for HDD swaps. The fan is managed via S.M.A.R.T.

Step 1 — Shut down and prep

1. Power off the iMac and unplug it.
2. Place it face-up on a soft, lint-free surface.
3. Have your new adhesive strips ready.

Step 2 — Separate the display

1. Starting at the top-left corner, slide the cutting wheel between the glass and the aluminum frame to cut the adhesive.
2. Work around the top and sides. Do not insert too deep near the bottom right—that’s where fragile cables sit.
3. Lift the display a few centimeters and support it.
4. Disconnect the LVDS/display data cable and the power cable from the logic board. Lift the panel away and set it safe-side up.

Step 3 — Remove the hard drive

1. Remove the fan (T10) and the speaker if they block access (model-dependent).
2. Unscrew the HDD bracket (T8/T10) and lift the drive.
3. Disconnect the SATA data/power cable from the HDD.

Step 4 — Install the SSD

1. Mount the 2.5″ SSD in the bracket/spacer (if required).
2. Connect the SATA cable to the SSD.
3. Refit the assembly where the HDD was and secure with screws.
4. Reinstall any parts you removed (speaker, fan).

Step 5 — Clean frames & apply new adhesive

1. Peel off all old adhesive from the rear case and the display.
2. Clean the mating surfaces with isopropyl alcohol.
3. Apply the new adhesive strips to the chassis in the correct orientation (follow the strip labels).

Step 6 — Reconnect and close

1. Reconnect the display power and LVDS cables.
2. Align the panel; once you’re sure cables aren’t pinched, press firmly around the edges to bond the adhesive.

Step 7 — macOS setup

• Power on while holding ⌘ + R to enter Recovery (or use a macOS USB installer).
• Open Disk Utility → View: Show All Devices → select the SSD → Erase (APFS, GUID).
• Reinstall macOS and migrate your data (from Time Machine or the old drive if you cloned beforehand).

Compatibility notes

• This guide is only for 21.5″ Late-2015 A1418 with a 2.5″ SATA HDD or Fusion Drive.
• If you have a Fusion Drive, the small PCIe blade SSD can also be upgraded, but that’s an advanced job (different parts/cable).
• Not compatible with 2011 thick iMacs or 27″ panels (different procedures).

Troubleshooting

• Black screen / no backlight: re-seat the display power and data connectors.
• Fan loud: ensure all sensors/cables are reconnected; check macOS/SMC resets (power cable unplugged 15 sec).
• Display not sitting flush: adhesive strips misaligned—reopen carefully and re-apply.

Parts & tools

• iMac 21.5″ (2012–2019) display adhesive kit
• 2.5″ SATA SSD (500 GB–2 TB)
• Torx T5/T8/T10 driver set, opening wheel, spudger