Gen 1 MES 40 won't maintain temperature

[Phil0219]

Long time reader; first time poster. Really appreciate all the tips and tricks i have picked up from you folks! I have a Gen 1 MES 40 (20070311) that I'm having trouble diagnosing a problem on. I have an email in to Masterbuilt CS, but haven't heard back.

The smoker is about 3.5 years old and I haven't had any issues with it until now. I noticed about a week ago that my smoker would heat up to the set temp and the heating element would turn off and wouldn't come back on. I set it at 275 and let it heat all the way up to 275, the element shut off and it coasted to 282. After that, the element wouldn't kick back on and the temp would eventually fall all the way to ambient. I tried it a few more times with the same result. I did notice after a few tries that i could unplug the smoker after the element turns off, plug it back in a few minutes later, and the element would turn back on and heat to the set point, but it wouldn't kick back on after the temp fell below the desired setting. I confirmed the temp and timer were set each time. Here's what I have done so far:

• I took the element out to inspect for cracks and check continuity - everything appeared to check out fine. The element had continuity between the contacts. I also confirmed there was no continuity between the outside of the element and the contacts or the mounting plate
• All of the connections looked good; no broke or rusted connectors or wires
• I took the controller off the top to inspect for corrosion or loose connections; everything looked good.
• Checked and cleaned the thermostat on the inside; from what i could tell it looked fine
• I reassembled everything and go the same result. It would heat all the way up to the set point and fall to ambient temperature.

Am I missing something? Could it be that the controller has a bad board? The display appears to be working properly; both the heating indicator light and power indicator light are working. I'm kind of left scratching my head on this one... Anybody ever had this happen to their smoker?

 

[GaryHibbert]

Evening Phil. First off, I'm a truck driver--with VERY limited knowledge about electricity.
From what you say about your MES 40 heating problem, my guess would be either your control panel circuit board or your safety roll out limit switch is bad.
When I had a problem with my MES 30 Gen 1 not heating up as it should, I ended up rewiring my MES, bypassing the control panel entirely and installing a PID. That solved my problem and the MES was back working better than new.
Now like I said, God knows I'm electrically challenged. I contacted tallbm and he walked me through the entire process. I've tagged him in this post and hopefully he'll jump in and give you his take on your problem. If not, then I would suggest you PM him and ask for his advice.
Sorry, but that's the best I can do to help you on this.
Gary

 

[tallbm]

Long time reader; first time poster. Really appreciate all the tips and tricks i have picked up from you folks! I have a Gen 1 MES 40 (20070311) that I'm having trouble diagnosing a problem on. I have an email in to Masterbuilt CS, but haven't heard back.

The smoker is about 3.5 years old and I haven't had any issues with it until now. I noticed about a week ago that my smoker would heat up to the set temp and the heating element would turn off and wouldn't come back on. I set it at 275 and let it heat all the way up to 275, the element shut off and it coasted to 282. After that, the element wouldn't kick back on and the temp would eventually fall all the way to ambient. I tried it a few more times with the same result. I did notice after a few tries that i could unplug the smoker after the element turns off, plug it back in a few minutes later, and the element would turn back on and heat to the set point, but it wouldn't kick back on after the temp fell below the desired setting. I confirmed the temp and timer were set each time. Here's what I have done so far:

• I took the element out to inspect for cracks and check continuity - everything appeared to check out fine. The element had continuity between the contacts. I also confirmed there was no continuity between the outside of the element and the contacts or the mounting plate
• All of the connections looked good; no broke or rusted connectors or wires
• I took the controller off the top to inspect for corrosion or loose connections; everything looked good.
• Checked and cleaned the thermostat on the inside; from what i could tell it looked fine
• I reassembled everything and go the same result. It would heat all the way up to the set point and fall to ambient temperature.

Am I missing something? Could it be that the controller has a bad board? The display appears to be working properly; both the heating indicator light and power indicator light are working. I'm kind of left scratching my head on this one... Anybody ever had this happen to their smoker?

HI there and welcome!

I agree with Gary. I think the rollout safety limit switch is failing u. If you have a newer MES there is a 2nd panel about halfway up on the back usually on the right side or in the middle. If you have that panel i bet the switch is burning up or connectors are wearing out/corroding.

If u dont have that panel than you have to remove the back of the smoker. If you have rivets (I hope) u drill em out then replace with sheetmetal screws. If not then u have to pry the back off out of its grooves and i would then fasten back with sheet metal screws. If you have a dremel or rotary cutting tool cut a panel for future access.

If that part is messing up then remove it and splice the wires until u can replace it. Let us know what u find and we can go from there :)

 

[Phil0219]

Well, it doesn't have the access panel, unfortunately, but the back is riveted on so it should be easy enough to remove. I'll get into that this evening after work. I do have a Dremel so I'll definitely be adding the missing access panel.

I really appreciate the help. I'll let you know what I find this afternoon.

 

[dr k]

Well, it doesn't have the access panel, unfortunately, but the back is riveted on so it should be easy enough to remove. I'll get into that this evening after work. I do have a Dremel so I'll definitely be adding the missing access panel.

I really appreciate the help. I'll let you know what I find this afternoon.

I've heard someone putting an ice cube on the dime snao disk safety sensor to reset it quickly to test. When you hit your set temp and the temp falls so it should heat, does tthe red heating light come on as the telmp continues to fall? That could be the open circuit at the snap disk. I used a dremel cut off wheel to carefully access the snap disk and resealed with alum duct tape incase mine fails I can bypass it. My light button started to turn off my smoker so I also did the PID. No conformal electronics coating on these outdoor appliance circuit boards/components will eventually short with condensing humidity, smoke and dust.

 

[dr k]

Bring controller inside in between smokes to keep it dry. I'd mount the screw holes to the edge of one by to sit on the top of the smoker opposite side from the vent. Unclip the two pin connectors bring it inside.

 

[Phil0219]

I've heard someone putting an ice cube on the dime snao disk safety sensor to reset it quickly to test. When you hit your set temp and the temp falls so it should heat, does tthe red heating light come on as the temp continues to fall? That could be the open circuit at the snap disk. I used a dremel cut off wheel to carefully access the snap disk and resealed with alum duct tape incase mine fails I can bypass it. My light button started to turn off my smoker so I also did the PID. No conformal electronics coating on these outdoor appliance circuit boards/components will eventually short with condensing humidity, smoke and dust.

The "heating light" on the control panel is illuminated when the temp is falling, which is what made me think of the control panel. I'll have to try the ice cube trick when I plug it back in.

HI there and welcome!

I agree with Gary. I think the rollout safety limit switch is failing u. If you have a newer MES there is a 2nd panel about halfway up on the back usually on the right side or in the middle. If you have that panel i bet the switch is burning up or connectors are wearing out/corroding.

If u dont have that panel than you have to remove the back of the smoker. If you have rivets (I hope) u drill em out then replace with sheetmetal screws. If not then u have to pry the back off out of its grooves and i would then fasten back with sheet metal screws. If you have a dremel or rotary cutting tool cut a panel for future access.

If that part is messing up then remove it and splice the wires until u can replace it. Let us know what u find and we can go from there :)

I pulled the back off to inspect:

• I noticed this panel on the bottom, opened it up to inspect while I was right there; all looks good.

• The insulation around the heating element is pretty burnt; is that normal? Also, the small box on the upper right side is a being a pain to remove (I'm assuming this is the safety roll out switch). I stopped tugging on it because i was afraid I'd break the wires. Does it just pull off? Almost feels like its glued on there or something.
• I also inspected all the wiring to make sure there weren't any breaks or burns and I didn't find anything.

 

[dr k]

The "heating light" on the control panel is illuminated when the temp is falling, which is what made me think of the control panel. I'll have to try the ice cube trick when I plug it back in.



I pulled the back off to inspect:

• I noticed this panel on the bottom, opened it up to inspect while I was right there; all looks good.

View attachment 448828

• The insulation around the heating element is pretty burnt; is that normal? Also, the small box on the upper right side is a being a pain to remove (I'm assuming this is the safety roll out switch). I stopped tugging on it because i was afraid I'd break the wires. Does it just pull off? Almost feels like its glued on there or something.
• I also inspected all the wiring to make sure there weren't any breaks or burns and I didn't find anything.

View attachment 448829View attachment 448830

When you look inside the smoker there should be two screws to hold on the roll out switch cover that looks like it's covered in insulation from the back and two screws securing that switch to the smoker.

 

[dr k]

I believe the extreme heat going up the back wall/corner around the top of the chip loader housing cooks the insulation pretty well and is normal. Some mentioned a crunchy sound pushing on the inside/outside of the smoker's right rear corner. It seems the roof of the chip loader slants toward the corner compared to the older boxy gen 1.

 

[MJB05615]

When you look inside the smoker there should be two screws to hold on the roll out switch cover that looks like it's covered in insulation from the back and two screws securing that switch to the smoker.

Quick question, I cannot keep my amnps tray lit no matter where in the smoker I place it. Am I better off switching to the tube? I have placed the tray everywhere inside the smoker, still goes out after 5-10 minutes. I initially light it with a torch and let it flame for 10 minutes til I get red coals. Tried preheating pellets in microwave, using less in the tray,etc. I always thought the tubes were more for higher altitudes? Any advice?
Thanks,

Mike

 

[dr k]

Since the controller red heat light is lit when the temp is falling it appears the sensor and controller are doing their job and the roll out switch is failing. A small jumper clip on cable to bypass the switch to test if the element heats or stripping and wire nutting the wires together.

 

[dr k]

Quick question, I cannot keep my amnps tray lit no matter where in the smoker I place it. Am I better off switching to the tube? I have placed the tray everywhere inside the smoker, still goes out after 5-10 minutes. I initially light it with a torch and let it flame for 10 minutes til I get red coals. Tried preheating pellets in microwave, using less in the tray,etc. I always thought the tubes were more for higher altitudes? Any advice?
Thanks,

Mike

@Bearcarver puts in the bottom rack and and puts the amnps over the element housing in the right rear corner. He may have that in his step by steps in his signature. I did the mailbox mod.

 

[MJB05615]

OK, I'll check. He's got a different model with top vent on left, not on right side. I'll relook. May try the tube as well, see if it stays lit better. Thanks.

Mike

 

[dr k]

OK, I'll check. He's got a different model with top vent on left, not on right side. I'll relook. May try the tube as well, see if it stays lit better. Thanks.

Mike

When people load too many chips and the smoker is a white out and you can't see your food through the window, all Mes models have a lot of turbulence going straight up from the element through the bottom rack, before it moves around and to wherever the vent is ontop. It's a wind tunnel to view how the airflows in your smoker.

 

[MJB05615]

I know it's pretty cool. I watch that as my window is cleaned after every cook. So I'm better off placing the tray on the bottom rack since the smoke come in from the chip loader side and travels up. I've done that in the past, but it still goes out after 5-10 minutes. I use the side MB slow smoke or Cold smoker attachment. I stopped using the chip loader years ago since it's terrible after the temp gets to the set point as you know. I happen to like the MB slow smoke attachment it produces plenty of smoke, I use the pellet tray when I try to get 2 different flavors of smoke going at the same time.
Once the attachment breaks, I'll most likely do the mailbox mod. But that's down the road. I'll go back to the bottom rack closer to where the smoke comes in and see if the tray stays lit longer. Thanks, I appreciate all of your excellent insights and advice.

Mike

 

[Phil0219]

OK, I'll check. He's got a different model with top vent on left, not on right side. I'll relook. May try the tube as well, see if it stays lit better. Thanks.

Mike

I have the AMNPS and the AMNTS and much prefer the tube. IMO, two tubes is perfect for me. I'll put one in at the start of a long smoke on the bottom left side of the cabinet. It'll last for about 6-7 hours. Once the first one is almost spent, I'll put the other one in right next to it to get me to the finish line. I do leave the chip loader about half way out to help with the air flow and have never had an issue with the tubes staying lit. I have, however, had some issues with keeping the tray lit.

 

[Phil0219]

When you look inside the smoker there should be two screws to hold on the roll out switch cover that looks like it's covered in insulation from the back and two screws securing that switch to the smoker.

Thanks! I had some time to tinker with it again last night and got the back cover off of the limit switch. The wires looked fine; no corrosion or broken spots. Only thing I noticed is one of the spades felt a little loose so I grabbed some pliers and crimped it down a little tighter. After all of that, I reassembled everything to see how it would cycle and it seemed fine.

I fired her up, took about 25-30 minutes to get to 275, it would coast up to about 280 each time, element would kick back on at 273, and repeat. I let it go for 4 on/off cycles before I shut it down. I don't know, maybe the loose connection on the limit switch was causing the switch to trip. Either way, it seems to be cycling as it should. I'll try to get a longer test done today; maybe let it run for 4 or 5 hours and see how it does. I appreciate the pointers and help thus far!

 

[MJB05615]

I have the AMNPS and the AMNTS and much prefer the tube. IMO, two tubes is perfect for me. I'll put one in at the start of a long smoke on the bottom left side of the cabinet. It'll last for about 6-7 hours. Once the first one is almost spent, I'll put the other one in right next to it to get me to the finish line. I do leave the chip loader about half way out to help with the air flow and have never had an issue with the tubes staying lit. I have, however, had some issues with keeping the tray lit.

Thanks. I'll get the tube and try this. I used to place the tray on the bottom left, and it still would go out after 5-10 minutes. I have taken the chip loader completely out a long time ago since I also use the MB slow smoke add on. I appreciate the advice.

Mike

 

[dr k]

Thanks. I'll get the tube and try this. I used to place the tray on the bottom left, and it still would go out after 5-10 minutes. I have taken the chip loader completely out a long time ago since I also use the MB slow smoke add on. I appreciate the advice.

Mike

A 3" diameter 24" long snap together aluminum vent pipe is about $3.00 @ a box store. Keep it that length or cut to length with tin snips while it's unfolded. Put the non tapered end, if uncut, in the chip loader hole and support it so it's horizontal. Slide lit tube in It so it's in the air intake stream. You'll need needle nose pliers and with out the tube cap pull it out or put it in when it's hot when done appling smoke. (I have the round fixed amnts, may be different with the oval adjustable amnts) Bend a hanger into a snake like shape and put in the vent pipe then the tube on it so it's elevated off the bottom of the vent pipe. Or cut a couple 2.5" lengths of the hanger and slide perpendicular through holes of the round tube to elevate/center in the vent pipe. I would fill tube half way and hold sideways and shake to level pellets and find how full you want it for your taste. It's the mailbox mod for the amnts without the mailbox in the pic below.

 

[MJB05615]

That looks like a very simple idea. Thank you. I'll definitely try it. It does defeat the use of the external MB Slow smoke attachment I'm currently using, but definitely provides the air flow needed to keep the amnts lit. And better flavor from the pellets than wood chips. I looked on Amazon, and the amnts 12" tube no longer available? I'll keep looking other sites for that particular one. There's other brands of tubes, but the amnts brand is best IMHO. Thanks for the advice.

Mike