Bosch 24 inch vented electric dryer model #WTA3510UCeat,but yhe Timed cycle has

[shillion]

My customer said she set the dryer to Max dryness,when it stopped,clothing was still damp wet.She started the dryer again on the same Max dryness setting hoping it would dry better this time.When the dryer stopped again after a few minutes,it was still damp.So now she used the Timed dry hoping it will force the dryer to dry the clothing more.It turned out she had to run the dryer on Timed dry 2 extra hours to finally get the clothing dry.The load was not too big,just a load from a matching Bosch washer.The Timed dry cycle has no heat.Only the air dryed the clothing,not the heat.This happened every time.That means the auto cycle has heat,the timed dry cycle has no heat,but the auto cycle cannot dry enogh,and the timed cycle took 2 hours more.Very frustrating.I was asked to find out why the Timed dry cycle has no heat.I realize may be the dryness sensor will need to be replaced because the dryer stopped too soon(LEAVING THE CLOTHING DAMP WET)..But why no heat on Timed dry cycle?I simply am not familiar with this Bosch design.On auto cycle,the drum would tumble one direction for about 10 seconds,stops a while,then reverse tumbling direction for 10 seconds,etc.But the heating pattern also changes.The dryer has 2 heaters of different wattages.I have a hard time understanding which heater comes on (or both come on,or alternating the heaters,why would it be necessary to be alternating?)After observing this action for 2 hours ,I still do not know what the computer control is doing,I give up.The 2 pages of electric diagram do not explain  the sequence of operation.Would anybody who is familiar with this Bosch dryer explain the sequence so those of us who do not can do some fixing?I would really appreciate it very much.Thanks a lot for your much needed help!

[shillion]

This is Shillion again.I made a mistake about the model # of the Bosch dryer.It's WTA3510UC,electric vented dryer.

[AJ]

Any updates for us?
What did you end up doing to repair it.
I don't see any Bosch appliances in this area so I'm not much help.

Thought maybe another tech would have had some advice.

[shillion]

Hello AJ,thanks for your concern about this Bosch dryer repair.I am still waiting for a  local repairman to give me some hints or info.I may just have to pass this job to that guy.I will post the results when I or other repairman get this done.Thanks again!

[AJ]

 

[nutznboltz]

Shillion,
If your model number ends with /UC13 you have a Canadian model which uses a special control module designed to meet Canadian engery requirements.  This control (#481590) uses reduced heat in the timed cycles.  Only one of the heater coils is energized and cycles on breifly.  According to Bosch manual the timed cycle on this Canadian model is for hand washables and delicates only.  For regular drying use the auto cycles which provide full heat. 
I too was baffled the first time I worked on one, also this arrangement is only on the vented models. The condensation models do not use the reduced heating. 


BOSCH Control Module Part # 481590



 

[nutznboltz]

Shillion / AJ
Added the service manual for this dryer to my dropbox.

[AJ]

shillion
Service manual sent via PM

[shillion]

Thank you very much,AJ & nutznboltz,your explanation is right to the poiont.My customer feels exactly the same.The timed cycle has very low heat.I explained to her.She may want to purchase the module which gives the full heat on timed cycle.Your explanation saved me a red face and a lot of wasted time trying to get the heat back.You guys did a really great job in finding the service manual.I hope others having the same trouble found this post and learn from it.My sincere thanks again!