Mercedes A45 AMG Window Stuck? Rear Glass Off Track

The Mercedes-Benz A45 AMG (W176) is a seriously fun hot hatch — but like many modern cars with semi-frameless-style door glass and tight window channels, it can develop annoying (and sometimes dangerous) window issues over time.

One of the most common complaints we see is rear door glass “popping out” of the tracks, where the glass slips out of the back channel and starts sitting crooked, grinding, or refusing to go up properly. It can happen gradually or suddenly — and once it’s out, forcing the switch can crack the glass, burn the regulator motor, or chew up the channel.

Quick model note: The W176 A-Class/A45 AMG was introduced in 2013, received a major facelift in 2015, and ran through to 2018 — and these window problems can show up across that whole range, including A45 AMG.

Common Symptoms (Rear Door Glass Popping Out)

If your rear window has popped out of the back channel, you’ll usually notice one or more of these:

Glass tilts forward/back as it goes up or down
Grinding / crunching noise inside the door
Window goes up halfway then jams or drops
Glass rises unevenly (one side higher than the other)
Window closes but leaves a gap at the top (wind noise / water leak)
You can see the glass sitting outside the felt channel near the rear edge
Switch works but you hear the motor strain (or clicks)

If you’re hearing grinding, stop using the switch immediately — that’s how regulators get destroyed and glass and tint can be damaged.

Why the Rear Glass Pops Out of the Track (The Real Causes)

On the W176 platform, rear window “popping out” is usually caused by misalignment or a worn guide system, not the glass itself.

1) Worn or loose rear window guide channel (back channel)

The rear channel lining (felt/rubber) can compress, tear, or become loose. When that happens, the glass can’t stay guided and starts to wander until it climbs out of the channel.

2) Regulator wear or bent arms/cable issues

If the regulator is worn, cables stretch, or the mechanism binds, the glass is pulled up at a slight angle. That angle is enough to push the glass out of the back guide.

3) Loose glass clamp / carrier

The glass is held to the regulator by a clamp or carrier. If that loosens, the glass shifts under load and will walk out of the channel.

4) Door impact or previous repair

A door that’s been slammed hard, bumped in a carpark, or previously repaired can have:

slightly bent inner door frame
mispositioned channel
missing/loose fasteners
Result: the glass runs crooked and pops out.

5) Dry, contaminated, or swollen channel rubber

Dust, old lubricant, or swelling rubber creates drag. The motor keeps pushing, and the glass binds then jumps out of the guide.

Front Window Issues Too (W176 A45 AMG)

You’re not imagining it — W176 A-Class models can also suffer front window issues, including:

window not sealing properly after going down
slow movement or “one-touch” behaving strangely
grinding noises
glass rocking forward/back
regulator failure (cable fraying, pulley issues)

The front doors get used more, so regulator wear tends to show up there first — but the rear pop-out issue is a classic “guide/channel + alignment” problem.

The Correct Fix (What Actually Works)

A proper repair is about getting the glass running straight again and making sure the guidance system is secure.

Step 1: Diagnose without forcing the window

We check:

whether the glass is out of the channel
whether the regulator is pulling unevenly
clamp tightness and door frame alignment
condition of the rear guide channel lining

Step 2: Remove the door trim and reset the glass into the channel

Once access is open, the glass is carefully reseated into the rear channel and centered.

Step 3: Adjust alignment and torque the glass clamps correctly

This is the big one. If you just “push it back in” without alignment, it usually pops out again.

Step 4: Repair or replace the worn parts

Depending on the cause, we’ll:

replace the regulator (if cables/mechanism are worn)
replace/secure the rear guide channel (if loose or damaged)
replace broken clips, fasteners, or carriers
clean and condition the channel (correct product — not greasy junk that attracts grit)

Step 5: Reset / relearn the window (where required)

Many Mercedes windows benefit from a relearn procedure so one-touch and anti-pinch behave correctly after repairs.

What NOT To Do (This Makes It Worse)

Don’t keep pressing the switch when it’s grinding
Don’t spray WD-40 or heavy grease into the channel (it collects grit and ruins the felt)
Don’t try to force the glass straight with your hands while operating the switch
Don’t ignore a small tilt — that’s how it becomes a cracked window later

How Auto Hero Fixes It Fast

At Auto Hero Roadside Assistance, we handle window regulator and channel issues all the time — including tricky Euro door trims and tight-tolerance glass alignment.

Our approach is simple:

diagnose the root cause (channel vs regulator vs clamp/alignment)
reset the glass correctly into the back guide
fix what’s worn so it doesn’t happen again
make sure the window is sealing and running smoothly before we leave

If your A45 AMG rear glass has popped out of the back channel, it’s usually very fixable — but the longer it’s left, the higher the chance of damaging the regulator or glass.