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jdpnagp
Apr 14, 2006, 01:42 PM
My Maytag dryer works well in the Timed Dry mode but in the Auto Dry mode it runs forever and does not dry well. In the Timed Dry mode it produces plenty of heat and works fine. What is happening in the Auto Dry mode that does not make the heat properly get to a level that allows the clothes to dry like in the Timed Dry mode? I suspect it is a thermostat or some moisture sensor problem. Help appreciated!

applguy
Apr 14, 2006, 03:32 PM
Autodry dryers don't actually "sense" the clothes. Only electronic dry dryers do that. The problem is most likely due to an airflow restriction somewhere. These usually occur in the vent duct that connects the back of the dryer to the outside of the house. These vents should be cleaned at least once every 2-4 years depending on what types of fabrics you usually dry, according to manufacturers. The best test for this is to pull the dryer out, disconnect the vent from the wall and start the dryer. Feel the amount of airflow coming out of the dryer, reconnect the vent and see how much air is coming out of the vent outside. It will be slightly less, but it should be close. If you cannot access the outside hood (on roof, etc.) you can also test this theory by disconnecting the vent from the dryer and try to dry a load in auto dry mode. If the load dries OK, then the problem is definitely in the vent. Any further questions are certainly welcome. Good luck.

jdpnagp
Apr 14, 2006, 04:55 PM
Please read the posting! The normal Time Dry works fine... therefore the venting cannot be the problem. Furthermore I have totally disconnected the vent and ensured airflow is smooth. There is no venting problem I guarantee. I don't know if mine is electronic or not and I don't know what you are alluding to regarding my dryer as one type or the other. It senses the moisture content when in the Auto Dry mode and turns off when the moisture is gone, i.e. the clothes are dry. Please reconsider.

applguy
Apr 15, 2006, 03:58 PM
I did read your post and I realize you said that time dry works OK, but that doesn't mean the vent is clear, trust me. After working on dryers for over 15 years, I think I know what I'm talking about. If I am going to be of any help to you, this needs to be dealt with in a systematic manner. Second, I'm glad you have removed the vent from the dryer, but you did not give that information in your first post. I'm not wanting to ellude to anything about your dryer, what I am telling you is that if your control panel says "auto dry", then it most certainly does not sense the moisture in the drum. Auto dry dryers utilize a system of cycling the timer motor with the element, and has nothing to do with how wet the clothes are. If there are 2 metal sensor bars inside the drum, then it is an electronic dry dryer, and then would sense the moisture in the clothes. I will also need a model and serial number so I can see exactly what dryer you have. Thanks.

2manytoys
Apr 27, 2006, 02:44 PM
applguy, I found and joined this forum while searching for the answer to the exact question in this thread. My problem is identical. I first thought of the "exhaust restriction" theory right off. So I pulled the dryer out, replaced the aluminum expandable duct work off and replaced it with new solid, 4" aluminum duct. I pulled the front off the dryer and disassembled the blower, including removing the squirrel cage and washing it thoroughly. I vacuumed every trace of dust out of everywhere. I reassembled and tested it only to find out that on "sensor dry", it shut off after 10 min. with the clothes still soaking wet. The heat is fine and all levels work. I run it on "timed dry" and it works fine. It has the two metal bars in the drum and it is a GAS dryer, not electric. It's a Maytag Neptune, 2002 model. Model number MD5500. It has worked on "sensor dry" perfectly until last week. The washer is removing the water properly so it's not that. I know this for sure, as the washer had had all its parts replaced 1 month ago. Got to love Maytag!!

applguy
Apr 27, 2006, 07:12 PM
The theory of operation is this: First, wet clothes are electrically conductive. As the wet clothes tumble, they touch the two metal bars in the drum. There is a capacitor on the control that is trying to build up a charge, but when wet clothes create a short from one bar to the other, this charge is released to the frame of the dryer, therefore discharging the capacitor. As long as the capacitor charge is low, the control knows the clothes are wet. As the clothes become dryer, they short the bars fewer and fewer times. Once the capacitor charge builds to a certain level, the control knows the clothes are mostly dry, and it advances the program to the final timed portion, usually less than 20 minutes, some of which is a cool down portion to reduce wrinkling. If your dryer is shutting off after only 10 minutes, that means the control capacitor is never getting discharged. This can be due to a few different reasons: 1. Blue or green wire behind the sensor bars is disconnected or broken; 2. Load is not large enough (remember the bars must be contacted repeatedly); 3. Bars are "coated" by fabric softener build up and need to be cleaned with Windex or 409. 4. Defective control board. 5. Airflow is restricted and moisture can't escape the drum. You have probably addressed the airflow possibilities well enough. Load size is probably not the issue, since you've had the dryer for a while. Clean the sensor bars and make sure the blue and green wires are connected well to the back of the block; orientation makes no difference. There is a diagnosic mode you can enter to test the control's ability to sense the bar contact that is illustrated in the tech sheet which is located within the control panel. Let me know what you find, or if you have further questions. Good luck. By the way, you do have a decent washer/dryer pair. Most of the problems these machines had were addressed before yours was built. What kind of repairs has your washer had?

2manytoys
Apr 28, 2006, 08:07 AM
Thanks for the reply applguy, much appreciated. The problem with the washer started with the "LR" code, lost rotor. There were 2 or 3 resistors blown on the motor control board. So, both the control board AND the motor were changed as the old motor wiring harness was not compatible with the new control board. Seems like a waste to me, as the motor was perfectly fine, but there must have been a change made that corrected the problem. The wax motor was fine. It really is a shame that Maytag has had these probs with these machines as they do work good when running. I have the tech. sheet and will try all you suggested, maybe today but more than likely Monday. I will let you know what I find. I've worked on a few machines before so I know my way around a fair bit. This digital stuff is just a little more intimidating but with sites like this, it should be no problem. The funny thing was, the repairman that came to look at the Neptune washer didn't know what the "LR" code was, I had to tell him. Go figure...

2manytoys
May 2, 2006, 07:32 AM
applguy, I ran the diagnostic found on the schematic. Everything checked out OK including the system check and pressing the "sensor dry" button and not getting a "normal" LED. If the "normal" led lit up, it meant the sensor bars were shorted. I removed the sensor bars and cleaned them with a SOS pad and reinstalled with the same results. The two wires were connected but they were both blue not blue/green as you suggested. When I push sensor dry, the machine starts at 63 min. then after 5 min. it goes to "cool down". It does this no matter what level of dry or heat setting you select. The temp. control appears to be working correctly as the exhaust pipe gets nice and warm on medium and hotter on Max. The dryer works fine on "timed" dry. What I'm wondering is, are you aware of a particular resistor that burns out on the control board? If so, I could replace the resistor and would be good to go versus replacing the whole frigging board. I could remove it and visually inspect it for "burns" but if you knew where the offending resistor is, it would help. Looking at the schematic, I see the wires from the "sensor" bars run to a "dryness sensor". Is this a possible problem area and is there really a "sensor" of some sort, further up the line? I am trying my best to avoid any contact with Maytag. I have given them enough of my hard earned coin. Appreciate your help, thanks...

2manytoys
May 5, 2006, 04:50 AM
Bump...

applguy
May 6, 2006, 03:45 PM
When you are in the diagnosic mode, you should remove one wire off the sensor bars and touch it to the other one to see if the light shows the bars are shorted. The point of the test is to see if the control "sees" a short on the bars or not. This test can be frivolous though because the diagnostic routines are a separate program on the control. The control can (and sometimes does) test OK in diagnostic mode but really isn't. I have had to replace the control board in the 5500 units only a couple of times, so it's not a common problem; it's fair to say it happens on all brands of electronic control dryers. Basically put, if it hits cool down after 5 minutes with a full load of wet clothes in it, but the diagnostic test shows the board can "sense" a short across the bars, then you have a bad control board. It's that simple (unfortunately). The 5500 is part of the third production phase on the Newton-built Neptunes. Most of the problems that the 3000 and 4000 series product had has been fixed in the 5500, 6500 and 7500 series units; The washer drive system failures are due to a vendor problem, so they now get them from a different vendor (which is why the new system is incompatible with the old system and must be replaced together), and I have yet to see one fail. The 3/4000 units had a machine control board (only in the washers, not the dryers) that had a whole mess of numbered resistors that could serve as a clue to find what component failed, but those boards are no longer in use. I have had people say they were going to try to repair their boards. They say they will call me and let me know if it worked or not, but they never do. I can only assume they were unsuccessful. I myself have never tried. I get the feeling from your question that you have been hearing or reading about these machines and I don't want to leave you with the impression that your machine control has problems that are similar to previous designs, because it doesn't. I would bet good money you won't find any blown resistors on this board. It's probably a problem with the software on the board and it just doesn't "read" the clothes correctly. All of the info I gave earlier about operation theory applies, but the two wires from the sensor bars simply connect to the control board. They haven't used a separate controller for years. Sorry, it's training time again, so I've spent a good part of the last week in training meetings and unable to check the posts.

2manytoys
May 7, 2006, 08:17 PM
Thanks for the reply, applguy. So, what you are saying is that, if I touch the two sensor bar wires together and get the "normal" light, it may OR may not mean the "sensor" signal is working? Correct? Now, if I touch the 2 wires and don't get the "normal" light, what does that mean? Is that a control board for sure? Maybe a stupid question but, is there a way 2 reprogram the software, maybe a factory reset? Just trying to cover all possible bases before changing the board. Is there a problem with running the dryer strictly on "timed" dry from here on in? Sorry for all the questions...

applguy
May 8, 2006, 05:09 PM
Questions welcome. If the light illuminates, it means the wiring to the sensor block and logic of the control is supposed to be OK (but not necessarily). If the light doesn't illuminate, then either the control is bad or one of the blue wires is broken or not connected at the control. The latter is the really useful angle for the test, because if you get the light and the drum is full of wet clothes, but the control hits cool down after only 5 minutes, then obviously the logic is flawed, so control replacement is imminent. There is no way to repair the programming, since we have no way of connecting to the control chip, and we don't have a "good copy" of the program. There is nothing wrong with using the timed dry cycle permanently. The whole point of the electronic dry cycle is to have the dryer run only long enough to dry the clothes. If you use a timed cycle, you're basically guessing at how long it will take, and if you guess wrong, you just have to run it again or you've wasted unknown amounts of energy.

2manytoys
May 8, 2006, 08:44 PM
Ok, applguy, you've been a great help with this. Thanks a lot for the quick response. I will play with it a bit more then replace the board if necessary. I understand the concept of "sensor" dry and it has worked almost flawlessly till now. The guessing part will definitely be a hassles for sure. I was confirming that the dryer was OK to use exclusively on "timed" dry in the interim, without causing any damage to the unit. I kind of figured it was no problem. I will post back with the results so you know what happens. Cheers bud.

Jim Smyth
Dec 28, 2008, 08:58 AM
Too bad 2manytoys never came back to say if he fixed the problem or not. I would suspect not.

I have a Maytag Model # MDG5500AWW Serial #40757878ZU dryer with the same issues. I went throuh all the normal tests which lead to to buying a new board. The new board doesn't work in either Sensor or Time dry, no ignition or 110V to the iginitor. Put the old board back in and your back in business in the time only function again, lites right off.

I was referred to a procedure that tells you when you put the new updated board in your now supposed to remove a capacitor by the radiant sensor because the new board has that already incoorporated into it. My dryer doesn't have that capacitor anywhere I can find it. That leads me to the burnt resistor area. Here's a picture of my old board on the left and the new one on the right.

http://www.smythcustomknives.com/images/DB1.jpg

You can see on the left one which is the original, the resistors are burnt looking. From looking over both boards I notice a few other differences too. On the original board towards the bottom there's a module that has Mtr/Gy on it. Look right under that and there a little square box that has a sliding little connector/jumper and you have 2 choices to where it can go. The only other time I have seen something like this in on my ceiling fan remotes so if you have multiple fans in different rooms you cant have any 1 remote work different locations. Now if you look at the new board on the top left right under the 4 resistors that arnt burnt you see a box that has no connector in it. I wonder if there needs to be a jumper in there somewhere?

Any help would be appreciated. Thanks in advance, Jim

Jim Smyth
Dec 30, 2008, 11:10 AM
I am up and running finally with heat again in the sensor and time dry modes. :)

It appears I plugged the J4 plug (its the one with 6 pins) in backwards. Long story short and I brain farted on my end. But if you don't get ignition in the time dry or sensor dry mode after replacing the LED board, you may want to check to see that you got the J4 is in the right way. There is actually only 5 wires out of the 6 spaces on the plug and it should be easy to make sure you plug it in right. But I can tell you it is possible to plug it in the wrong way. :o

2manytoys
Jan 7, 2009, 09:21 AM
Too bad 2manytoys never came back to say if he fixed the problem or not. I would suspect not.

I have a Maytag Model # MDG5500AWW Serial #40757878ZU dryer with the same issues. I went throuh all the normal tests which lead to to buying a new board. The new board doesnt work in either Sensor or Time dry, no ignition or 110V to the iginitor. Put the old board back in and your back in business in the time only function again, lites right off.

I was reffered to a procedure that tells you when you put the new updated board in your now supposed to remove a capacitor by the radiant sensor because the new board has that already incoorporated into it. My dryer doesnt have that capacitor anywhere I can find it. That leads me to the burnt resistor area. Heres a picture of my old board on the left and the new one on the right.

http://www.smythcustomknives.com/images/DB1.jpg

You can see on the left one which is the original, the resistors are burnt looking. From looking over both boards I notice a few other differences too. On the original board towards the bottom theres a module that has Mtr/Gy on it. Look right under that and there a little square box that has a sliding little connector/jumper and you have 2 choices to where it can go. The only other time I have seen something like this in on my ceiling fan remotes so if you have multiple fans in different rooms you cant have any 1 remote work different locations. Now if you look at the new board on the top left right under the 4 resistors that arnt burnt you see a box that has no connector in it. I wonder if there needs to be a jumper in there somewhere?

Any help would be appreciated. Thanks in advance, Jim

Hey Jim, sorry for not posting what took place until now. I tried every angle to get the sensor dry working again. I finally had to replace the whole board. Sears came to my aid and we split the cost 60 40 in favour of me. That was 6 months ago and the machine has been working fine since. I wish I could tell you about the capacitor you mentioned but I never saw the tech guy remove anything but the new board. I was with him all the time and he never went anywhere but the back pannel. As a matter of fact, he was a little stumped himself as all tests on the old board showed it was good but just didn't work. He left me the old board. I sure hope you get your dryer working. Thanks for the update...

xyzzy
Dec 20, 2009, 11:36 AM
I just the same experience after replacing the drum rollers and idler. The problem was I was not careful enough with the seal from the lint tray to the blower on reassembly. Resulting in the blower sucking cold air from the floor.

Being more careful on next assembly the problem went away.

BluesBrother
Feb 10, 2011, 06:58 PM
My particular problem was that in Sensor Dry mode, the clothes were NOT dry, even though the cycle appeared to run and finish normally (although it was somewhat shorter than it should have been). The timer appeared to run normally and shut the dryer OFF at the end of the cycle, but only the lower half of the Dampness Indicator Light was illuminated; the top half, which should have flickered on and off with wet clothes, remained dark.

I checked all of the "usual suspects": I thoroughly cleaned the dryer vent, cleaned the sensor (literally, two parallel strips of metal), and checked the wiring at the sensor. Nothing. Everything checked out fine. The heating element had been recently replaced (see below) and was working fine. I was stumped.

As applguy explains above, the operation of the Sensor Dry (also called Auto Dry) is quite simple. There are only 3 parts: the sensor, a dampness indicator light, and a simple ciruit board. The circuit board powers the timer. In Sensor Dry mode, the wet clothes repeatedly short the metal bars of the sensor, causing the Dampness Indicator to flicker on and off, and resulting in the Sensor Circuit Board NOT supplying power to the timer motor. Thus, during the early part of the cycle, while the clothes are still wet, the timer does NOT advance. As the clothes get dryer, however, they don't effectively short the bars of the sensor, and the Sensor Circuit Board begins to supply power to the timer motor, intermittently at first, then continuously, causing the timer to advance towards the end of its cycle. By the time the timer reaches the end of its cycle and shuts the dryer off, the clothes should be dry.

So, having checked everything else out, that left only the Sensor Circuit Board itself as the likely culprit. I ordered a replacement, at a cost of about $75. The replacement part is identical in function, but a different (somewhat more complicated) design (the dryer, a Maytag, is over 12 years old). I replaced the board, put the dryer back together, and prepared to admire my handiwork! You can imagine my chagrin when the dryer performed exactly as it had before replacing the board: the timer ran continuously, the cycle was too short, and the clothes weren't dry when the dryer shut off. What the..

I studied the wiring schematic for a long time, and I simply couldn't come up with a rational explanation for this strange behavior. Since I had eliminated all of the "obvious" causes, I was forced to consider "unlikely" causes - and there weren't many of those! One side (metal bar) of the sensor is connected to the Sensor Circuit Board; the other side (metal bar) of the sensor is connected to the frame of the dryer. So I began by eliminating the sensor from the circuit, grounding the sensor input of the Sensor Circuit Board directly to the frame of the dryer. No joy, a somewhat surprising result, given that this was a brand-new circuit board!

Looking at the schematic again, I noticed that the neutral leg of the 3-wire 220VAC supply is supposed to be grounded to the frame of the dryer by a ground strap (note: some local codes do not permit such grounding). The Sensor Circuit Board was connected directly to Neutral on the terminal block. This meant that the Sensor Circuit Board was dependent upon an electrical path from Neutral through the dryer frame, the sensor, and back to the Sensor Circuit Board. But I was surprised to discover that there was no ground strap from Neutral to the frame of the dryer, meaning that the frame of the dryer was not electrically grounded. It was "floating" above ground.

So the solution turned out to be electrically grounding the frame of the dryer to Neutral, so that a complete electrical circuit would exist from Neutral, through the frame and the sensor, back to the Sensor Circuit Board. Once I did this, the dryer worked fine again; the timer didn't advance until the clothes were no longer "wet", and when the cycle was done, the clothes were dry.

Now, the obvious question, of course is, how did it work before? I have no idea. The only "explanation" I can come up with is that we had the dryer worked on recently to replace a burned-out element. After that, the element worked, but the Sensor Dry mode did not. I can only speculate that the repairman inadvertently changed or disturbed something that resulted in the Sensor Dry mode no longer working, as it had before his visit.

classicshar
Mar 3, 2011, 08:23 PM
I have the same problem (result) caused by a very simple fact: the blue wire disconnected from the 'plate' and I don't know how to attach it back to the plate. (One end is floating in the drum. How do I get it to stay under the plate?) I think I can figure out how to put the plate onto the drum with the two provided screws. (Mine just 'shook loose') Is there a written or diagram instruction. Thanks so much; love this 'old' combo!

yhill
Jun 27, 2011, 09:49 AM
AppleGuy, I have a 3000 Maytag series. The dryer works on the heavy load. Where should I begin to start trouble shooting my problem?
The clothes do not dry completely on any other cycle setting.
Thanks YYH

drtom4444
Jun 27, 2011, 10:35 PM
The auto mode is controlled by two t-stats. One where air exits for reheating and the other where it enters drier drum. I would suspect they are out of calibration and need replacing. They have numbers stamped on them for different temps and are oval with a screw on each end and two wires. More than likely your drier is dirty which can also cause the problem. Dirt and lint residue build up on the inside of the air passages and block the sensors. You have to disassemble the drier and scrape and wash out the parts, except the motor-vacuum it out and then clean out blower fan, too. Don't be shy about taking it apart-the dirt builds up everywhere and will cause a fire. Then clean out exhaust vent pipe. This will probably cure your problem. DrTom4444

drtom4444
Jun 27, 2011, 10:37 PM
What "plate" are you talking about? DrTom444

drtom4444
Jun 29, 2011, 02:45 PM
There are two t-stats that regulate the auto dry cycle one where air leaves drum and another where air enters drum. One or both are bad or there is dirt and lint buildup on the ducts. Clean it and it will probably fix it. DrTom4444

eosneadwd6eoeff
Nov 23, 2013, 04:57 AM
I had the same problem and the repair man told me the fabric softener sheets coat the moisture sensor which should be cleaned from time to time or better yet don't use them.