Whirlpool gas dryer troubleshooting - thermostadt or gas valve???

Hello. I've got a Whirlpool gas dryer, Ultimate care II with the moisture sensor, about 15 years old. I've read some troubleshooting messages and I've looked at some online parts ordering websites that give me diagrams of my specific dryer.
Problem: The dryer works but is very slow to dry clothes. There is absolutely no obstructions in the ductwork or the internal, dryer ductwork. I've laid the dryer down on the front side and removed the back panel. I've opened up the internal ductwork and can see that it is clean.
By the way, although it seems it's getting warm while running, it definitely is not getting to normal heat temperature.
Looking at the diagrams from online, I see a few items that may be the culprit but I don't know for sure.
First, there's a fuse (white, sealed plastic). I checked continuity and it's fine. There's a safety high heat thermostadt on the heat duct coming from the gas heat source and then there's another thermostadt on the fan blower housing that I think is the 'regular' thermostadt. I've checked continuity on both of these. The safety thermostadt indicates good but the regular thermostadt only moves the continuity meter over half way. Hmmm.
There's a moisture sensor that totally confuses me because there's only one wire going to it. I don't understand that logic.
Finally, theres talk on line about a gas supply valve or something. I haven't been able to find that.
Any ideas on what I should replace first? I've got a local parts supply house and none of the parts seem very expensive. The dryer works great (except for now) and I hate to throw it out and spend $500 to $600 when it's only a $20 part to fix it.
By the way, the gas supply line is providing gas at normal pressures. I checked to make sure none of the shutoffs were partially closed.
One more question please. Am I able to bypass any of the thermostadts or moisture sensor temporarilly in order to try and isolate the problem?
Thanks!
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On Thu, 10 May 2007 04:15:32 -0700, wklkj wrote:

Probably a weak gas valve. Just replaced one on a Fridgidare dryer last year.
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#1 Offishul Ruiner of Usenet, March 2007
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The moisture sensor's second wire(if necessary) is provided I would assume by it being grounded to the chassis. A common problem with this dryer is the moisture sensor becoming covered with a waxy substance from the use of dryer sheets. It then doesn't sense the moisture in the clothes and the dryer goes into cool down phase. Cleaning off with alcohol solves that problem. I would think you could check it by checking for continuity between the sensor surface and that wire . Otherwise, I would be suspicious of one of the thermostats...the fact that it is getting some heat rules out the white sealed fuse..when that goes the burner won't come on at all.
Tom G
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Thanks Tom.
Is it true that the moisture sensor switch you're referring to would only be applicable if I was using the moisture sensor setting? If I set it to a standard time setting on the dial, wouldn't that disable the moisture sensor even if it was broken? I hope I'm wrong because that would be an easy fix.
Also, if it's the moisture sensor, could I disable it by simply grounding the wire and then not use that setting?
Thanks!
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If you use a timed setting, the moisture sensor would be out of the loop. If it still is taking a long time to dry and not getting hot, then the problem is not with the moisture sensor. I would look at one of the thermostats being the culprit...not letting the dryer get up to temp..or perhaps the temp control on the console.
Tom G
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In the timed cycle, the moisture sensor circuit is out of the loop. Other posters suggest that you look at the thermostats. Well, it is highly unlikely that the stats are your problem. Think about it: a thermostat just doesn't wake up one day and decide that he will stop working at 100 degrees instead of 165. It either works or doesn't.
I would suggest that the coils on the valve are your culprit. There are two. Replace them both. There should be a bracket that holds them to the valve. Remove the bracket, and the coils come off freely. But, if you have a really old style of burner where the coils and wiring are integrated and hard to remove, you'll need to change out the whole assembly.
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AE Todd, you are right on. I called a local appliance parts supply shop and he said the same thing you did.
For others reading this who may benefit, here's what he said to do: There's a little access hole (about as big as a quarter) on the front dryer panel on the bottom left. Pry it off. It is an access hole to enable you to see the gas flame in operation. He said, turn on the dryer and patiently watch inside the hole. First you'll see the orange glow of the igniter, then the gas flame will ignite. Watch while the gas flame burns and then shuts off. That means the thermostadt is operation and is shutting off the gas at the proper temperature. Continue to watch this cycle and he guessed at at the third or fourth cycle, the igniter will turn on with the bright orange glow but the gas will not turn on and you will not get a flame. After a few seconds of glowing, the igniter will shut off and the dryer continues to run but the gas flame never came on. He said, if that happens, it is the coils. $20 to replace both and AE Todd, you are right, they simply unplug electrically and there's a very simple bracket that holds them in place. They slide right off.
Quite frankly the most difficult time I had was trying to figure out how to get to the coils. I ended up taking the top of the dryer off and then the front panel (with the door).
Thanks again for the help!
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