Need service manual for Maytag MEDB400vq

[kskarci]

Need service manual for Maytag MEDB400vq. Don't see it on this site. Any assistance would be greatly appreciated.

[kskarci]

Minor correction: MEDB400vq0

[whirlpooltech]

I have attached a copy of the tech sheet, maybe the closest thing you will find to a service manual.

What is wrong with it?

[kskarci]

Thanks for this. I am getting no heat. Used this tech sheet to run through the heater tests. Checked the high-limit thermostat, exhaust thermostat, thermal cut-off fuse,  inlet thermistor, heater element.. Everything seems to be either reading the correct resistance or showing normal continuity.  Only thing left is the control board as far as I can figure. Can't believe that this 2yo drier is already costing me this much.. 

Also.. the diagnostics on this machine were telling me the inlet thermistor was shorted (f25). It's not.. I went so far as to replace it to make sure. Wondering if perhaps it's just a failure on the control board or perhaps an old code from before I got the machine..

[kskarci]

I'm a bit at a loss here. Hoping someone has some ideas.. As stated above.. The dryer suddenly ( a couple weeks ago ) stopped heating. This is true in all mode, even timed dry.

I have put the dryer into diagnostic mode w/ a new board and there are no codes being returned. All diagnostic tests look good. Door switch, Moisture Sensor, Motor / Heater / Drum LIight ( heater actually turns on when I run this test ), inlet airflow is over 40 CFM, Line voltage looks fine at 250v or so per the diagnostic.

I've checked the inlest and exhaust thermistors both on the units themselves and at the wiring harness up at the control board. The thermal cut-off fuse is showing continuity as is the high limit thermostat and heater coil.

Not sure what else to do?

[tgoods]

Check the voltage drop at the heater relay while the dryer is running.  If you get 240vac, you know that the relay is not closing.  Since you already replaced the control board and the inlet thermistor, you can probably rule those out as being the problem.  Since the heat comes during diagnostics, you can rule out the motor switch.  That pretty much leaves the exhaust thermistor.  I know you said it checked good, but I've seen bad thermistors that tested good before. 

[kskarci]

I'm reading 100v at the relay w/ the dryer plugged in and not running and 245v during the timed cycle when the element should be heating but is not.. So perhaps the exhaust thermistor?

[tgoods]

I think so, if only by process of elimination.  Hope you can send that control board back.

[kskarci]

I'll give it a shot. Got the board at appliancepartpros so returning should not be an issue. Thanks for the hand!

-Ken

[kskarci]

OK.. No luck.. I consider myself to be pretty good at troubleshooting these kinds of problems but this one is completely evading me.

Again, my problem is no heat in any cycle.. Timed dry or sensor.

Let me run through my recent barrage of tests along w/ their results:
1.   Replaced the control board just to be sure that was not a factor.
2.   Replaced the Inlet Thermistor / High level Thermostat Assembly.
3.   Replaced the exhaust thermistor.
4.   Put dryer into diagnostic mode. No codes are being returned. No codes saved on the board.
5.   Ran inlet air flow diagnostic. Reading 60 CFM so this is certainly not an issue.
NOTE: Heater element turned on during this test.. I was getting heat
6.   Ran line voltage diagnostic. Display is reading 249 or thereabouts.
7.   Ran the Motor, Heater, Water, Drum Light and Console ID diagnostic.
NOTE: Heater element turned on during this test.. I was getting heat
8.   Ran the Manual Load Test. Progressed through Wet, Damp, Cooldown and Dry parts of the sequence. Everything tested fine..
E.G. I was getting Heat w/ out issue in the cooldown and dry stages.
9.   Disassembled the dryer (again )
10.   Checked to be sure I had continuity at the thermal fuse. No open circuit. Wiring looks fine.
11.   Checked to be sure I had continuity at the thermal fuse. No open circuit. Wiring looks fine.
12.   Checked to be sure I had continuity at the thermal fuse. No open circuit. Wiring looks fine.
13.   Didn’t bother w/ checking continuity on the heater element as there is no way it would have worked during diagnostics if it was broken.. Same goes for the other cut-offs and fuses but I’m grasping at straws here.
14.   Measured the resistance for the exhaust thermistor at the control panel wiring harness. Readings were in normal range.. At  the time the dryer was still a bit warm from the diagnostic run so it was reading about 9.2k.
15.   While checking reading at the wiring harness I also looked at the inlet thermistor. It was reading within normal range as well.

At this point I feel as though I’ve looked at every component in the heating circuit multiple times.
Not only that but I’ve replaced the inlet thermistor, high limit thermostat, exhaust thermistor and control board.

Still no heat in any of the timed dry or sensor cycles. I’m completely stumped.

Any other ideas from any of you seasoned pros? I refuse to accept defeat!

[RegUS_PatOff]

... diagnostics ... telling me the inlet thermistor was shorted (f25). It's not..

did you test it at the plug where it connects to the Controller ?
The wiring may be "shorted"

[kskarci]

Yes. Checked both the inlet and exhaust thermistors at the harness. I went so far as to get the heater running in diagnostic mode and then checked them both as they were cooling down to be sure the resistance was changing.. Everything looked as per the normal ranges.

[kskarci]

Correction.. I didn't check the thermal fuse 3 times

Checked the thermal fuse, the high-limit thermostat and the thermal cut-off.. All had continuity.

Copy and paste mishap.

[tgoods]

I'm stumped.  You've been very thorough.  When you measured 245v at the heater relay, that told you two things.  That the relay was not closed, and that the rest of the heater circuit was good.  It would be rare, but maybe you got a bad new control board.

[kskarci]

I'm going to try another board.. While I'm waiting for that; Someone on another forum mentioned that they thought they had seen a service flash for these dryers indicating that if the dryer heated in diagnostic mode but not normal use to replace the user interface board. I can find no reference to this although I don't have access to the resources some of you guys do. Is there somewhere that can be searched for these kind of service bulletins?