May 6th, 2007, 10:45 AM
Bosch SMU4052UC/14 stuck in cycle
Ten-year-old SMU4052UC/14 (SMU4052UC14?). At the top of the door front, this model has a rotary timer on the left side, beneath a horizontal mechanical cycle indicator (like a sideways thermometer). Mechanical power button and four mechanical cycle buttons are on the right side. The power buttons and cycle buttons have round indicator lights above them.
Last week I noticed the wash took too long. So the next wash I checked the timer position every five minutes. It got stuck at at the 3 o'clock position. I let it sit there for ten minutes and then manually advanced it a click. It later got stuck at 7:30. Again I let it sit there for a few minutes and then manually advanced it a click. It then finished the wash. I have repeated this twice.
I have read the info at http://www.applianceaid.com/boschDW.html and unfortunately other than the soap dispenser, information there is for SHU models (newer?) rather than my SMU.
(1) In normal operation does the timer periodically stop? Or does it always move at a constant rate the entire wash cycle? For example, is there something like a dirt sensor that pauses the timer to make sure the water clean?
(2) How long should a wash cycle be? My owners manual does not state.
(3) I want to access the timer and electronic guts at the top of the door. There are three philips screws on each side (edge) of the door that appear to hold the trim panel. There are three torx fasteners on the interior edge of the door, through the stainless steel interior panel. How do I get to the timer?
Thanks for your assistance.
May 6th, 2007, 11:12 AM
Wash Stall and Rinse Stall
I found a timing diagram for this dishwasher on the appliancepartspros site, through the link in Jake's announcement at the very top of this forum.
I have not digested it but there is a wash stall and rinse stall marked on the diagram at approximately where I am seeing the timer switch stop. So apparently it stops on purpose. But doesn't resume as quick as I think it should.
Maybe once I figure out how to read this diagram in conjunction with the circuit diagram I can tell how this is supposed to work.
May 6th, 2007, 01:43 PM
Heating element not working?
I now understand how to read the timing diagram. That is fantastic and should be part of the owners manual. It explains how the cycle settings control what the dishwasher does, how long each lasts, what operations are performed and what the water level is at any time during the cycle. For example, I never knew that on the economy setting the wash cycle heats to 125F (lower than usual) and the dry cycle does not heat at all.
So when operating correctly, at the "wash stall" and "rinse stall" points the timer motor is disabled until the temperature rises high enough to trip either the 125F thermostat (economy) or the 161 thermostat (normal). At that point the cycle continues.
I ran the washer at both economy and normal setting and it sat at the stall points for ten minutes each before I manually advanced the timer. So I presume either (1) the thermostats are defective or (2) the heating element is defective.
I vote for a defective heating element because it is unlikely that both thermostats would fail, and there are definitely two completely separate thermostats not part of the same circuit. Has anyone replaced the heating element on a Bosch SMU 4000 series dishwasher? Can I test my heating element to make sure it is defective? For example, should it have specific resistance value? Would an open circuit indicate a defective element?
Item number 470431 Heater-element $88.20
May 6th, 2007, 03:47 PM
Heating element partially works
A bit more information... I finally realized I could run just the dry cycle to test the heating element. So I did. At the end of the cycle, the countertop above the dishwasher normally gets warm. It did not. I opened the door and stuck my hand in. A bit warm but definitely not blazing hot. The silverware and plates were luke warm. Usually they are too hot to touch. Then I got the dumb idea to touch the heating element itself. It was very hot but did not burn me.
This ten-year-old diswasher has the heating element visible in the bottom of the inner liner. This is not one of the newer Bosch models with the flow-through water heater. So this should be an easy part to replace.
As far as I can tell from the circuit diagram and wiring diagram, this model does not have a circuit card. So this problem is not likely to be caused by the infamous melted solder connection.
So I am looking for advice - should I purchase a new $88 heating element?
August 2nd, 2010, 01:16 AM
Fix for my SMU4052UC/14
I had exactly this problem with my Bosch Dishwasher SMU4052UC/14.
Problem turned out to be a break/burn-out in the wire feeding the heater circuit.
This model has a weakness with the wires that go from the timer and push-button switches down to the active components under the unit. The wires run down the front of the door and are flexed each time the door is opened or closed.
Removing the door front by removing the six torx fasteners visible on the inside stainless steel door reveals the timer, cycle switches, and the wiring. The wires run through a vinyl cover that gives them some support where they flex as the door opens and closes. You'll need to cut that open with a utility knife (right around where it flexes) to see the damage if you have this same problem. Then run a new wire through the vinyl harness cover and use crimp connectors to patch it into the circuit.
I had this same problem with the power conductor a couple years ago (dishwasher wouldn't turn on or show neon power light).
After patching in a new length of wire for the heater conductor, all is back to normal.
Actually, the water inlet solenoid seems funky, so I've ordered up a new one and will put that in next week, but the "getting stuck at 3:00 and 7:30" problem is gone now.
Hope this helps someone else with the same problem.
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