Bosch washer dryer not heating on drying cycle
Hi all, I've been reading through this amazingly helpful forum and have found a lot of similar issues, but I've now reached a dead end, I'm hoping someone can give me some guidance.
My Bosch washer dryer is this model: wvd24520gb/01
On every dry cycle it stops after 15 mins, and the element never gets hot at all.
Here's what I've checked:
- The fan is spinning and air is circulating
- Water is entering the condenser and being drained
- The thermostat hasn't tripped, and has continuity as expected
- The NTC sensor has the expected resistance, 4.8kOhms at room temp, which falls when heated
- The element has the expected resistance, 36 Ohms
It seems to me like everything is working, but for some reason power is still not being delivered to the element. Is there anything else I can check? Or any other suggestions as to what might be broken?
Solution Summary
AI-generated from this discussion
This thread was marked as solved. Here's a summary of the problem and the fix, generated from the discussion below.
Bosch WVD24520GB/01 washer dryer stopped heating on drying cycle due to faulty PCB relay solder joint
- The problem
- Bosch washer dryer WVD24520GB/01 would stop every drying cycle after about 15 minutes and the heater element did not get hot.
- Likely cause
- Confirmed faulty electrical connection on the small PCB behind the main control board: a blackened and cracked solder joint on one leg of a white relay marked HF3FD. Earlier forum advice also suggested a faulty connection or broken wire, with PCB fault as a possibility.
- What fixed it
- The owner isolated the appliance from the power, removed the front panel and plastic housing to access the small PCB behind the main control board, inspected the board, found the damaged relay solder joint and resoldered it. After reassembly the dryer worked again.
- Checks to try
- Fan was spinning and air was circulating
- Water was entering the condenser and being drained
- Thermostat had not tripped and had continuity
- NTC sensor measured about 4.8 kOhms at room temperature and resistance fell when heated
- Heater element measured 36 Ohms
- PCB inspection found a blackened and cracked solder connection on a relay leg
- Parts or tools mentioned
- Small PCB behind the main control board
- White relay marked HF3FD
Safety: Appliance was unplugged before access. Further diagnosis should be carried out by a suitably qualified appliance engineer.
3 Answers
Hi. If all components are OK you have to suspect a faulty connection or broken wire (inside the plastic). Or a fault with the pcb, or timer if fitted, which I would definitely not gamble on changing as it's too expensive with no guarantee of a fix.
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Thanks Andy,
I actually found a fix for this, so posting in case it helps anyone else. I decided to check the circuit boards for anything obviously wrong.
This is what I did:
- Unplugged power, took photos of everything so I could remember how it went together, then unplugged all connections onto the boards
- Removed the front panel of the machine, which allowed me to remove some of the plastic housing and detach the small PCB that sits behind the main control board.
- Checked anything that looked like a relay, and sure enough found a blackened and cracked looking solder connection on one leg of a white relay (search "hf3fd" to see what the relay looked like)
- Resoldered this connection, put everything together, and it now works again :)
Excellent. That’s a faulty connection alright. Well played.
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