Wirlpool dryer AWZ 3303

[lockett]

Intermitting drying fault.
Drying three loads, first two loads dried as normal, the third load did not dry. Vent pipe blowing cold, checked the heating element, removed it from the dryer, first connected the heater directly excluding the thermal switches worked fine, checked the thermal switches continuity on both switches, Reconnected the wiring as was. Vent blowing hot.

Any ideas?

 

[Harry Bloomfield]

Intermitting drying fault.
Drying three loads, first two loads dried as normal, the third load did not dry. Vent pipe blowing cold, checked the heating element, removed it from the dryer, first connected the heater directly excluding the thermal switches worked fine, checked the thermal switches continuity on both switches, Reconnected the wiring as was. Vent blowing hot.

Any ideas?

Check for poor/over-heated terminals, on the heater circuit.

 

[jj4091]

If you did 3 loads one after the other could it possibly have overheated. I would check the lint filter and all of the vent stystem for any obstructions or fluff build up, don't rely on the fact you can feel an airflow at the exhaust or the lint light hasn't come on.

 

[lockett]

Thank you for your help. Heater terminals are as new, no blockage in vent, lint filter is clean. The dryer is like new but getting heat from the wife to replace it, I hate adding to land fill.

 

[jj4091]

Thank you for your help. Heater terminals are as new, no blockage in vent, lint filter is clean. The dryer is like new but getting heat from the wife to replace it, I hate adding to land fill.

As I said could it have overheated with continuous use and then reset itself once cooled.

Call your local Whirlpool engineer then. But I think he may struggle to diagnose an intermittent fault unless it is a known fault.

 

[Harry Bloomfield]

Thank you for your help. Heater terminals are as new, no blockage in vent, lint filter is clean. The dryer is like new but getting heat from the wife to replace it, I hate adding to land fill.

Maybe just the over-heat stat tripping, then. If it happens again, just leave it to cool down, then see if it fixes itself.

 

[lockett]

Failed today on the first load. Does anyone know if you can have an intermittent problem with a thermal switch. although the switches have continuity does this tell you how the switches perform in operation.

 

[Harry Bloomfield]

Does anyone know if you can have an intermittent problem with a thermal switch. although the switches have continuity does this tell you how the switches perform in operation.

Lots of things can suffer intermittent operation, including thermal switches, relays, and elements.

For tracing such intermittent problems, the best way is to devise a bit of test equipment, able to test at numerous test points, simultaneously. I made such a devise many years ago, for that purpose, with eight inputs, working on mains voltage.

Test point___________capacitor_________LED___________N

A 4001 diode is connected across the diode, reverse biased (or another LED), to prevent the LED being blown.

That circuit is then repeated 8 times over, or how ever many test points you might need. All the N(eutrals) are connected together.

Once built, that is connected to both sides of the element, the thermal cutout output, the input, the output of the relay from the PCB. Next time it fails, the lit LED's, will indicate where it has failed, and where you need to concentrate your attention.

 

[jj4091]

Failed today on the first load. Does anyone know if you can have an intermittent problem with a thermal switch. although the switches have continuity does this tell you how the switches perform in operation.

It's not a good plan to throw parts at a machine to try and repair an intermittent fault. Does switching off and back on get it to operate If not then while the fault is showing test for a voltage across the element and to earth if if nothing showing to establish if you are loosing the live or neutral. I think it will be more likely to be loosing the live as other comonents would probably not work if you lost the neutral. If you establish there is no live at the element then test for a voltage to earth along the path of the supply to to the element as Harry says. Possibly a poor connection in a plug and socket somewhere in which case having some contact cleaner ready would be helpful.

 

[lockett]

Thank everyone for their help. Thank you Harry for your suggestion, but what you suggested is above my technical knowledge.
Thank you jj4091, the element works fine, heats up, if you feel the back of the drum you can feel the heat from the element. All the contacts are clean, as I said in my first email inside the dryer is like new. When stripping the dryer all the contacts were clean and a very tight on the terminals.
Do dryers have thermostats and circuit boards, could the fault be caused by one of these failing.

 

[Harry Bloomfield]

Do dryers have thermostats and circuit boards, could the fault be caused by one of these failing.

Yes, yes, and yes!

 

[jj4091]

So the dryer is working again. As Harry says the answers to all your questions are yes. The next time the fault appears then those are the places you need to test for a voltage input and output at each component. No output at the element obviously.
Unusually you can download a service manual for your model here

WHIRLPOOL AWZ 3303 SERVICE MANUAL Pdf Download

View and Download Whirlpool AWZ 3303 service manual online. Air Vent Electronic. AWZ 3303 dryer pdf manual download.

www.manualslib.com

 

[lockett]

Thank you for the link. Looking at the manual the thermostats are not a replaceable part, the full element has to be replaced, £55. I don't know if I would spend this amount on a old dryer if my diagnostics turns out to be wrong. I agree with your comment "It's not a good plan to throw parts at a machine to try and repair an intermittent fault" I would have no problem spending the money if I could identify an easy to test part like a relay or thermal switch. I hate the idea of scrapping a appliance for what might be a simple fix. I could get an engineer to have a look at the machine. but this would not be cheap, (they have to made a living) same go's for trying different parts. I'm going to have a final try at finding the fault tomorrow, with the help of the suggestion posted here,
Thanks All for your help