Question 1

it's leaving dark gray or black smudges on my light-colored clothes, only in certain spots.

Accepted Answer

DIAGNOSIS That's grease or carbon dust. It's coming from a worn drive belt (the belt that turns the drum) rubbing inside the cabinet, or, more likely on this model, from the drum support rollers or their axles which require lubrication. FIX Unplug the dryer and remove the front panel (requires removing the top panel first, then several Torx screws around the door opening). Inspect the large drive belt for signs of fraying, glazing, or black dust around it. Look at the two or three white plastic drum support rollers at the bottom rear of the drum. Spin them by hand. If they squeak, feel gritty, or have visible black residue on the roller or its metal shaft, they are the source. Replace any worn rollers and clean the metal shafts with rubbing alcohol before installing new ones. IF THAT DIDN'T WORK The black marks could be mold from chronic moisture if you never run the 'Empty Dry' or 'Drum Clean' cycles, or if the drain system is faulty and leaving the drum damp. Clean the drum with a vinegar solution. HEADS UP Don't just wipe the drum and continue. The contamination will recur until you replace the failing mechanical part. Running it with dry, unlubricated rollers can score the drum's glide path, necessitating a full drum replacement.

Question 2

dryer won't turn on at all, no lights, no display, no response when i press the power button.

Accepted Answer

DIAGNOSIS Total loss of power. This is almost always an external electrical issue, not an internal dryer failure. Check your house's circuit before tearing into the machine. FIX Verify the dryer is plugged in securely to a working 120V outlet (this is a plug-in 120V appliance, not a 240V). Check your home's circuit breaker or GFCI outlet that supplies the dryer. Reset the breaker or GFCI. Test the outlet with another appliance (like a lamp) to confirm it has power. If you have it connected to a smart plug or surge protector, bypass it and plug the dryer directly into the wall. IF THAT DIDN'T WORK The only common internal failure that causes total blackout is the main control board. If you have verified 120V power at the terminal block inside the dryer (requires removing the top panel and a multimeter), then the board is likely dead. HEADS UP Bosch dryers have no internal fuse you can easily replace. If the control board is dead, it's often due to a power surge. For the replacement, consider adding a high-quality surge protector at the outlet.

Question 3

the inside of the drum feels gritty and it's getting on my clothes, like sand or lint pellets.

Accepted Answer

DIAGNOSIS You have a lint breach. The fine felt filter (the seal around the condenser) is either damaged, improperly seated, or the condenser housing itself has a crack, allowing raw lint to bypass the filtration system and get blown directly into the drum. FIX Remove and inspect the blue plastic condenser filter. Look at the gray foam gasket seal around its frame. Is it torn, detached, or missing? Look into the empty slot where the filter goes. You should see a fine mesh screen. If that screen is ripped or has a hole, lint is getting through. Run your finger around the drum interior while it's empty. If the grit is concentrated near the door, the main door seal might be breaking down. IF THAT DIDN'T WORK The issue may be internal. The ductwork between the evaporator and condenser can develop cracks, especially if the machine has been moved roughly. This requires disassembly to inspect. HEADS UP Stop using the dryer. Inhaling that fine lint is a health irritant, and letting it circulate can eventually clog the heat exchanger, leading to a catastrophic repair bill. Replace any damaged seals or filters before another cycle.

Question 4

i get an 'e67' error code sometimes, machine stops. manual is useless, what does it mean?

Accepted Answer

DIAGNOSIS E67 is a drain system error. The dryer's pump can't move condensate water out of the machine fast enough, or at all, so it shuts down to prevent overflow. FIX Check the drain hose connection at the back of the dryer and at the drain standpipe/sink. Ensure it's not kinked, crushed, or pushed too far into a standpipe (which can create a siphon seal). Clear the drain pump filter. Open the kickplate at the bottom front, unscrew the black cap over the pump, and remove any lint, hair, or coins. Also pour a cup of water into the pump housing to check it pumps freely. Ensure the dryer is perfectly level front-to-back and side-to-side. If tilted forward, water can pool incorrectly and trigger the error. IF THAT DIDN'T WORK The drain pump itself may be weak or failing. You can test it by listening for a distinct humming sound during a cycle—if it's silent when it should be pumping, the pump motor is dead. HEADS UP Never extend the factory drain hose beyond the recommended length. Excess hose coiled up can create loops that trap water and air locks, which will cause intermittent E67 errors.

Question 5

there's a high-pitched whining or whistling noise coming from my bosch dryer, sounds like it's from the back.

Accepted Answer

DIAGNOSIS That's the sound of a dry bearing on one of the fan wheels (usually the main circulation fan for the heat pump system), or less commonly, a foreign object touching the fan blades. FIX Unplug the dryer and pull it out. Remove the rear service panel (several Torx screws). Inspect the large black plastic radial fan (the circulation fan) for any debris like a sock, coin, or lint clump caught in the blades. Remove it. Manually spin the fan. If it spins freely but the noise persists when you spin it, or if it feels gritty, the bearing in its motor is failing and the fan/motor assembly needs replacement. IF THAT DIDN'T WORK The noise could be from the smaller fan on the compressor itself. This is a more involved repair, as it's part of the sealed refrigerant system's external cooling. HEADS UP Don't run the dryer with this noise. A failing bearing can seize, which can burn out the fan motor or cause the overheated fan to melt its housing, leading to a much costlier repair.

Question 6

dryer is taking over 3 hours for a normal load, everything is just damp, not drying on any cycle.

Accepted Answer

DIAGNOSIS This is almost always a severely clogged air system. The heat pump can't exchange heat efficiently if airflow is blocked, turning it into a slow, cool dehumidifier. FIX Clean the main lint filter (inside the door). Immediately clean the secondary condenser filter (blue fins in the bottom front slot) thoroughly under running water as described in the first fix. Check and clear the drain pump filter. Open the small kickplate at the bottom front (may require a coin or flathead screwdriver). Place a towel down, unscrew the black cap, and clear any debris from the filter and the pump housing. IF THAT DIDN'T WORK The evaporator (inside the machine, behind the condenser filter) may be coated in a felt-like layer of lint. This requires partial disassembly to vacuum it out—a common issue if the condenser filter wasn't cleaned regularly. HEADS UP Heat pump dryers are inherently slower than vented dryers, but 3 hours is a failure mode. After cleaning, run an 'Empty Dry' cycle on high heat to reset the system's performance baseline.

Question 7

new bosch heat pump dryer just beeps and shows 'door' on the display, won't start at all even though it's shut tight.

Accepted Answer

DIAGNOSIS The door switch isn't being engaged, usually because the door isn't aligned perfectly with the strike plate on the dryer body, or the strike plate itself is out of position. FIX Open and close the door firmly. Listen for a distinct click. If no click, inspect the small rectangular plastic strike plate on the dryer cabinet, right next to the door latch. Push it in with your finger—you should hear/feel it click. If it's loose or doesn't click, the plate is likely misaligned. Loosen the two small Phillips screws that hold it, reposition it so the door latch hits it dead center, and retighten. IF THAT DIDN'T WORK The door switch mechanism inside the cabinet behind that plate may have failed. This requires removing the top panel to access and test/replace the micro-switch. HEADS UP Never force the door shut. If alignment is off, forcing it can break the plastic latch or bracket, which is a much more expensive fix than adjusting the strike plate.

Question 8

my bosch 800 dryer keeps stopping mid-cycle and flashing 'clean filter' but the lint filter is spotless, what gives?

Accepted Answer

DIAGNOSIS The machine is detecting a restriction in the air path, but it's not your main lint filter. The secondary condenser filter, which is the real workhorse for catching lint in a heat pump dryer, is likely clogged. FIX Open the door and locate the condenser compartment at the bottom front of the drum opening. Pull the filter frame straight out. Rinse the blue plastic fins under running water, using a soft brush (like a dish brush) to scrub between every fin until the water runs clear. Do this in the opposite direction of airflow. Let it air dry completely before sliding it back in. A wet filter will trigger the error instantly. IF THAT DIDN'T WORK Check the exterior vent hose and wall cap for a bird's nest or heavy lint buildup. Even a slight kink in the flexible hose can cause enough back-pressure to trigger the sensor. HEADS UP You need to clean this condenser filter every 1-2 months, not once a year. It's the #1 cause of performance issues and extended dry times on this model.

Bosch WTW87NH1UC 800 Series Heat Pump Dryer

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