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gsegal 01-26-2013 08:03 PM

Dishwasher Thermostat
I'm trying to repair my daughter's dishwasher. It's a Frigidaire FDB750RCC0. The schematic shows the WASH boost thermostat connected to the Yellow/blk wire and when I pulled it out it was the 154227805 thermostat. The schematic shows the RINSE boost thermostat connected to the orange wire, which was the 154227808 when I pulled it out.

On another forum I found a post that stated the Rinse thermostat was the 154227805. Can anyone verify which is supposed to which?

Next I need to know what the trip temperature for each of these thermostats should be? I have no intention of paying $60 for a $7 themostat (the other one is $15). I can order any temp replacement I want for about $7 from digikey, but I need to know what the trip points are supposed to be.

Thanks for any help!

hardwareman 01-27-2013 06:21 PM

why are you replacing thermostats?

gsegal 01-27-2013 08:02 PM

I was really just looking for an answer to the two questions I posted:
1) What are the trip points for the 805 and 808 thermostats
2) Which one is supposed to be the RINSE boost thermostat (connected to the orange wire).

If it helps me to get an answer to those two questions, then I'm replacing the thermostat because it's defective (i.e. timer halts waiting for thermostat to switch on). Yes the heater element and high temp thermostat are fine. I need to know the specs on the thermostats so I can test the precise trip point of each of the two boost thermostats, to verify if one/both need to be replaced, and also which replacement to order (I can get pretty much any temp trip point I want in the same case).

gregzoll 01-27-2013 08:08 PM

These are all of the thermostats for that model

Also there is no way you are going to find that one thermostat that is $60 for anything cheaper, unless it was pulled out of a old unit.

hardwareman 01-27-2013 08:41 PM

normally the temps are printed right on the disc.

gsegal 01-28-2013 11:37 PM

So the thermostat that was connected to the orange wire (RINSE boost) is marked as follows:
36TMV02 21442 S0341
F122-25F 154227808

The other one is marked:
36TMV02 21439 S0343
F117-25F 154227805

So do you think the F122 and F117 are the temp trip points,
i.e. 122 degrees F for the rinse and 117 degrees F for the wash?

Does it make sense that the rinse would heat to thigher temp than the wash?

If this is the case, then I would be an idiot to pay $50 more for the one thermostat, seeing as that's only a 5 degree difference in trip point.

I can get a 122 degree F thermostat for $8 from Digikey. They also stock a 110 degree F. So I will likely go with either another 122F, or the 110F as a replacement for the 117F. Again, I am dumbfounded as to why they would have a different thermostat for the rinse vs wash, especially within 5 degrees!? And even more curious as to why there is a $50 price difference (they are the same series part so is must be supply/demand). I guess their engineers have never heard of DTC.


ddawg16 01-29-2013 12:36 AM

Does your heated dry work?

I just replaced the heating element in my dishwasher.

gregzoll 01-29-2013 07:43 AM

It really depends on that thermostatic device. Yes, it could be that not too many people purchase that one item is why it costs more, it could also be the internals, which makes it more expensive than the other. Keep in mind that ordering parts through a non-certified supplier, that the manufacturer does not certify for their parts, you are leaving it in your own hands.

If the machine is over 5 years old, then you can find out that you are going to continue having to make repairs on it.

gsegal 01-30-2013 12:47 AM

As stated, the heating element is fine (as would be the over-temp thermostat, for the element to work). The issue is a defective temp boost thermostat which will leave the timer un-powered until the heater heats up the water sufficiently to trip the boost thermostat.

Over this small a temp range the guts of these thermostats are nearly identical (simple bi-metal disc switch) - certainly nothing that would drive any cost difference, other than the usual supply & demand.

As I said, why a manufacturer would choose a less common part that is 5X the cost to get a few degrees different for a rinse cycle compared to the wash cycle is beyond me. I'm ordering two of the 122 degree thermostats for $7 each and the wash and rinse boost will heat to the same temp.

That unit is about 5 to 7 years old based on the house age. My own Kitchenaid dishwasher just past 10 years and I have only replaced the water solenoid in that unit.those And the piece of junk GE I had in my last house went 17 years without me ever having to open it up.

In fact, I sold my last house of 17 years with all the original (low-end) appliances (washer, drier, dishwasher, oven, A/C) still operational. And I'm now 10 years into my second house which I equipped with higher-end appliances. They all still work, but I did have to replace a $5 starting disc in the fridge and a control panel in my double oven. ($400 was way too expensive for a keypad & controller - next time I vow to build my own oven controller using a $100 Android Tablet - plus then I can surf the internet while I cook).

Zoll, you sound like the salesman at Sears when I built my new house ;-)
... I told him how my original Kenmore washer & drier were still on the job and without blinking he told me "no way these new units will last you that long!" I told him he should consider another line of work.

Now for my rant: They ought to flog the moron that would design that dishwasher circuit since leaving the heating element on indefinitely can be dangerous (yes I realize there is an over-temp thermostat, but relying on single point safety to prevent your house from burning down is just stupid - my friend's Maytag recently melted the racks inside). There are safer ways to boost the temp (I can think of one example with no additional parts that would have two failsafes to prevent an overheating condition).


JasperST 01-30-2013 07:31 AM

So you think the design is dangerous but you are willing to use cheap knock off parts?

hardwareman 01-30-2013 10:00 AM

have you even tested these thermostats to determine which one if any is bad? Where does timer stick, in rinse or wash?

paintdrying 01-30-2013 01:37 PM

The designs for the dishwashers are stolen for other designers, they are reverse engineered by unqualified engineers. Different engineers are working on different parts of your appliance. To the dismay of my family I will only run the dishwasher at the start of dinner. I realize these dishwashers are fire hazards. It will take a cute little blonde girl to die before our government is actually willing to protect us from something that may actually harm us.

gregzoll 01-30-2013 02:45 PM

Wow, looks like someone forgot to take their meds today.

hardwareman 01-30-2013 05:56 PM

yeah, that one is a head scratcher. Maybe to many paint fumes.

gsegal 02-01-2013 01:29 AM


Originally Posted by JasperST (Post 1105514)
So you think the design is dangerous but you are willing to use cheap knock off parts?

Where did I say I was going to use "cheap knock off parts"? Cantherm is one of the leading manufacturers of thermostats - nothing "cheap" or "knock-off" about them. They are inexpensive, not because of their design, but because I am choosing to buy them from an electronics supplier rather than from an appliance parts house. The price has nothing to do with cost to manufacture or quality, and everything to do with supply & demand.

I suppose there are people out there who may sleep better at night knowing they paid $60 for a thermostat - expensive has to be better, right? Just don't tell them the manufacturer of that thermostat sells the exact same part to a different market area for $7.

And yes, I absolutely characterize a design that can allow a heating element to remain energized indefinitely, in an appliance that is commonly set to run while people are sleeping or out of their homes, as "dangerous". Particularly since the timer could easily be used as a secondary failsafe with zero impact to cost or parts count. But, I could be wrong since I've only been working as an electrical engineer for 30 years ;-)

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