Bosch HBN 642 -- single oven cycles and doesn't get above 325
I own a 7-8 year-old Bosch wall mounted single oven, HBN 642 A UC.
Problem 1: in bake convection and regular bake mode, oven would operate fine when used for shorter periods -- up to, say, 40 minutes. When operating for longer (say, 45+ minutes), the unit would stop heating and would not heat up again until completely cooled down. (I.e., the "heat" light would go out, convection fan would stop, no heat to elements, and unit would cool down, regardless of position of control or temp. switch.)
I attempted to troubleshoot by carefully removing and disassembling the "thermometer" and cleaning the contacts. Re-assembled and re-installed.
Problem 2: Now the unit only heats up to, say, 325, then cycles -- heat on, heat off -- every 5-7 seconds when the unit reaches 325. (Yeah, I probably made the situation worse.) Problem exists in both regular and convection mode, except the convection fan cycles as well in convection mode.
Would you recommend a new thermometer? New high temp. sensor? If a new thermometer is needed, do they simply install without any adjustment to the part?
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Re: Bosch HBN 642 -- single oven cycles and doesn't get...
WHAT WAS HAPPENING AT 1ST YOUR HI-LIMIT TERMAL SAFETY OR OVEN TEMP SENSOR FELT THAT THE OVEN WAS GET TOO HOT AND SEIZING OPERATION UNTIL SAFE TEMP WERE OBTAINED THIS IS GENERALLY A FAULTY OVEN TEMP SENSOR. I WOULD ADVISE YOU TO CONTACT A CERTIFIED TECH TO LOOK AT IT AND P.S. DON'T MENTION THAT YOU TOOK THE MACHINE APART MOST SERVICE COMPANIES WILL NOT SERVICE THE MACHINE IF IT BEEN TAMPER WITH BY THE CUSTOMER DUE TO INSURANCE AND LIABILITIES
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I detected a similar problem following the sudden appearance of Err1 in the display. (Oven 4-5 years old, and the grill element failed when it was 3-4 years old). This indicated a temperature sensor problem. My local dealer came with his Thermocouple and confirmed an "under temperature" reading on the standard and baking settings. I agree that the fan setting is probably OK. He replaced the sensor. I monitored the situation for a while and was not happy because an under temperature could be quite dangerous when cooking certain foods, and also causes problems when baking bread.
The location of the oven sensor is also a problem because it is at the top right by the grill which also serves as the top heat source.
I had corresponded with Bosch about this and their response was, frankly, less than satisfactory. In the end I decided to call out their engineer (cost £85-ish) who wired my oven up to his computer. In the end he said that the oven was working as it should be (despite it taking a very long time to actually reach the target temperature of 200C.
In my view of I want 200C, then I should get 200C, not an approximation.
Interestingly the secret info (not in the manual) is that the temperature bar readout does not indicate that it has reached the actual temperature, but may be 90% of the temperature (so if you want 200C you get 180C.
An unsatisfactory solution is to get an oven temperature of the meat probe type and put that in the oven, then you will get a more accurate reading of the temperature. You would need one that goes above 200C (my first one only goes to 200 but I have found another that goes to 250C). Mine is by CDN model DTP482, any good cook shop should stock this.
Hi, If your electric oven is not heating then you probably have a bad heating element in your oven. This is not that hard to fix yourself... Check out this tip that I wrote about the Oven not heating problem..
you can obtain the instruction manual for this directly from the bosch web site free of charge if it is not listed there try the BSH Home appliances ltd site they are the manufacturers repair service in the UK
After the oven is switched off, the after-run of the cooling fan is controlled by an electromechanical thermostat switch. The fan can switch back on, due to residual oven heat that accumulates within the oven's outer case and reactivates the cooling fan temperature switch.
Considering yours is making buzzing sounds and activates on and off, the fan's thermal switch may have dirty contacts or just be defective and require replacement.