Kenmore Gas Dry won't heat--good air flow

Hello Brian;


My name is Peter. I am a retired field service appliance technician.
Recently, I worked on a LG gas dryer. I Ohm the thermostat and found that to be bad, but when I Ohm the ignitor I got a reading of 135 Ohms. I replaced the ignitor. The new ignitor Ohm reading was 167. In other words, the ignator did glow red, but did not have the power to open the gas valve.
Although, you checked the electrical continuity of the gas valve, that does not check the mechanical issues. Sometimes the spool in the valve sticks or does not fully open. You need to hit it with a hammer and turn the dryer on. Repeat this about 8 times.
Make sure your hot air distribution manifold is not plugged up. This too will shut your unit down.

Gas Dryer no heat: or shuts down soon after heating CHECK:

Thermal Fuse
If the air flow in the dryer is restricted, the temperature in the heating chamber can get hot enough to blow the thermal fuse. If the fuse blows, it cuts power to the coils that control the gas valve. The fuse is usually mounted to the exhaust duct just inside the back panel. You can check its continuity with an ohmmeter. If, after disconnecting the fuse, you get any reading other than 0 when you touch the leads of the meter to its terminals, it has blown. There's no way to restore it -- you'll have to install a replacement.

Igniter and Gas Valve Coils
TEST with a multi meter: The igniter is an electric conductor that works like the element in an electric heater, glowing hot enough to ignite gas when you turn on the dryer. This conductor can burn out, and when it does, it may glow, but it won't get hot enough to ignite the gas. At times it may give a reading of continuity yet fail mechanically and not get hot enough to ignite flame though it gets hot and glows and even may show Ohms or continuity ( close circuit) ?

Occasionally, the Gas safety valve and the electric coils that control the gas valve are defective -- they can wear out when the dryer gets old. When this happens, the igniter glows, but gas never enters the heating chamber or does not stay consistant.
Performing a continuity test on either part will help you determine whether or not you need to replace it. But the coils should also be tested for amount of resistance as well as Ohms. As they may be showing ohms yet not putting out enough resistance to keep proper gas pressure flowing. Most coils should show at least 1300 ohms ( GIVE OR TAKE 150 OHMS). Anything significantly less Thus u get an ignition but then it soon goes back out. The flame does not stay lit.

Air Flow and Heat
The motor that drives the tumbler also drives a fan that circulates air through the heating chamber and the tumbler and expels it through the vent. If the air can't circulate, perhaps because of lint blockage, the heating chamber overheats, which prompts the cycling thermostat to turn off the gas. The thermostat resets when the chamber cools, but the chamber heats up quickly and the thermostat again shuts off the gas. The result is that the temperature in the tumbler doesn't stay hot, and your clothes take longer to dry, if they get dry at all.

Warning
There's a big difference between a dryer that doesn't heat up at all and one that just doesn't get hot enough to dry your clothes. In the first instance, the problem is usually a defective part, and things should be back to normal after you replace it. In the second instance, the problem is caused by restricted air flow, and you need to clear the lint filter and vents and take steps to prevent lint build-up. If you don't, you'll use more energy for drying than you need and the dryer may continue to malfunction. Worse, you may have a dryer fire.

GOD IS GOOD !!!! AND THAT IS WHY MY ADVICE IS FREE

Gas Dryer no heat: or shuts down soon after heating CHECK:

Thermal Fuse
If the air flow in the dryer is restricted, the temperature in the heating chamber can get hot enough to blow the thermal fuse. If the fuse blows, it cuts power to the coils that control the gas valve. The fuse is usually mounted to the exhaust duct just inside the back panel. You can check its continuity with an ohmmeter. If, after disconnecting the fuse, you get any reading other than 0 when you touch the leads of the meter to its terminals, it has blown. There's no way to restore it -- you'll have to install a replacement.

Igniter and Gas Valve Coils
TEST with a multi meter: The igniter is an electric conductor that works like the element in an electric heater, glowing hot enough to ignite gas when you turn on the dryer. This conductor can burn out, and when it does, it may glow, but it won't get hot enough to ignite the gas. At times it may give a reading of continuity yet fail mechanically and not get hot enough to ignite flame though it gets hot and glows and even may show Ohms or continuity ( close circuit) ?
Occasionally, the Gas safety valve and the electric coils that control the gas valve are defective -- they can wear out when the dryer gets old. When this happens, the igniter glows, but gas never enters the heating chamber or does not stay consistant.
Performing a continuity test on either part will help you determine whether or not you need to replace it. But the coils should also be tested for amount of resistance as well as Ohms. As they may be showing ohms yet not putting out enough resistance to keep proper gas pressure flowing. Most coils should show at least 1300 ohms ( GIVE OR TAKE 150 OHMS). Anything significantly less Thus u get an ignition but then it soon goes back out. The flame does not stay lit.

Air Flow and Heat
The motor that drives the tumbler also drives a fan that circulates air through the heating chamber and the tumbler and expels it through the vent. If the air can't circulate, perhaps because of lint blockage, the heating chamber overheats, which prompts the cycling thermostat to turn off the gas. The thermostat resets when the chamber cools, but the chamber heats up quickly and the thermostat again shuts off the gas. The result is that the temperature in the tumbler doesn't stay hot, and your clothes take longer to dry, if they get dry at all.

Warning
There's a big difference between a dryer that doesn't heat up at all and one that just doesn't get hot enough to dry your clothes. In the first instance, the problem is usually a defective part, and things should be back to normal after you replace it. In the second instance, the problem is caused by restricted air flow, and you need to clear the lint filter and vents and take steps to prevent lint build-up. If you don't, you'll use more energy for drying than you need and the dryer may continue to malfunction. Worse, you may have a dryer fire.

While the drum is rotating you should hear the CLICK associated with the gas valve assembly powering up to give out a blast of heat. If ya don't hear no click check the duct fuse. Right next to the control thermostat. If it is blown it kills the circuit to the gas valve assembly. If that fuse is good and the control is also good, then check the flame sensor for continuity, If it is open then the ignitor won't glow. The ignitor must glow and change in resistance then the flame sensor must open up and kill power to the ignitor so that power will be shifted to them coils on the gas valve.

If you need further help, reach me via phone at https://www.6ya.com/expert/dan_73bbd84fe1d95b61

The way it works is the coils the ignitor and the flame sensor are all powered up when the control thermostat calls for heat.

If all of these are good then look for these fuses

Any of these open and yall won't have no heat


This one does not have a pilot light. It is all automatic. When the control thermostat falls below 105f then it closes and powers up the gas assembly, all of the components are powered up at the same time. The ignitor has to reach 1800f to make the flame sensor trip and when it trips the power gets diverted to them coils. So make sure yall are getting power to the gas assembly first and then check the ignitor and sensor for continuity.. The ignitor does 2 jobs, it lights the gas and acts as a thermocouple once the flame is lit. if for some reason the gas were not to ignite then once that puppy cools down it shuts off the gas flow and that is your built in safety. The control thermostat alows power to the gas assenbly only until the drum temp reaches 160f. Then it opens and stops the power to the gas assembly. This is going on and off all throughout the drying process and it is normal to hear a click and a whoosh every so often. The flame does not stay on.

If you need further help, reach me via phone at https://www.6ya.com/expert/dan_73bbd84fe1d95b61

The glowing if the ignitor indicates that the circuitry is good but the flame/radiant sensor is bad and/or one or both of the gas valve solenoid coils are not working. The flame/radiant sensor bypasses one the solenoid coils then when power is applied to the ignition circuit, the first coil opens the first valve, the ignitor glows and the flame/radiant sensor gets heated. It's contacts then opens when heated enough to unbypass the second coil and allow the gas to flow and be ignited.

Make sure the flame/radiant sensor is properly in place and aligned with the ignitor to allow proper heat sensing. You may check the continuity between the sensor's contact terminals as the ignitor glows. At first, the terminals should read close (zero resistance) and then open (infinite resistance) after about 30 seconds or so. If this is not the case, the sensor is not working and must be replaced.

The solenoid coils, one with 2 prongs and the other has 3, sitting on top of the gas valves must be both replaced if the flame/radiant sensor turns out good. But before doing so, make sure to run a test with the dryer completely assembled because sometimes the gas do not ignite when the dryer's cabinet is open. This is to prevent unnecessary replacement of the coils.

Feel free to update us about the result and if you need further advice.

Unlike electric dryers gas dryers will continue to run if the thermal fuse is blown. Usually some sort of air blockage will cause the thermal fuse to blow. The control thermostat powers up the gas assembly. It judges the drum temp as air passes over it on its way out the exhaust. It opens(quits sending electricity to the gas assembly) at 160f for cotton and closes(starts sending power to the gas assembly) again at 105f.
When the dryer is running and the timer is set for heat, the control thermostat is energised. It powers up the flame (ignitor) sensor, the ignitor, and the solenoids. The gas does not come out with those solenoids energised because the ignitor is using most of the power to get it lit. When the ignitor is glowing wide open the heat from it causes a bi-metal in the flame/ignitor sensor to bend and open the circuit to that ignitor. That kills power only to the ignitor. The resulting power surge causes the solenoids to yank open them flood gates and raw gas comes out onto that screaming hot ignitor. KAWOOOSHHHH Houston we has ignition. At this point the ignitor becomes a safety device. As long as the flame is washing through that ignitor the current keeps flowing to them solenoids and the gas keeps a coming. If for some reason their was no ignition the ignitor would cool down and shut off the solenoids. More here


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Check the ignitor underneath the drum. (You have to open the panel to see it) It should glow shortly after the dryer starts, then the flame starts and the ignitor shuts off. If the ignitor does not glow then it or the thermostat is bad. If the ignitor is glowing but the gas does not light then the flame sensor may have to be replaced. If the gas ignites but does not stay on either the flame sensor or the coils are at fault.
See also: http://home.howstuffworks.com/how-to-repair-a-dryer.htm
If everything above is OK then the thermostat or the auto sensor is not working correctly.

The typical gas dryer set up: A thermostat is positioned on the blower housing to judge the drum temp. Next to it is a fuse. If the temp exceeds 350F then that fuse melts and kills the heat but the dryer will still run. When that thermostat wants heat it sends 120 volts to the gas assembly. The gas assembly consists of 2 coils a sensor and an ignitor. The coils work on 120 vac but they are tenderfoots. If anything is running on the same circuit with them they don't cooperate. Enter the big bad ignitor and its cousin, the flame sensor. Both these partners in crime work together to coax them coils into opening. How? The sensor ALLOWS power to the ignitor. When the ignitor is glowing hot as 3 yards of C of C hell then the sensor's bi-metal shuts that glow thingy down. This gives them voltage starved coils a chance to get busy. The surge of power energizes them coils and they yank up the gas gates, the raw gas flows out onto that screaming hot glow thingy and BOOM! Houstion we have ignition!!
As the temp rises inside the drum the control thermostat decides enough is enough and kills power to that gas assembly. The drum continues to rock and roll till the temp cools off and then the control thermostat calls for more heat. So what can go wrong? The flame sensor can die and not put power tot hat ignitor. The ignitor can die too. or both can be ok and the coils work a tad and then get hot and quit.


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Hello
Welcome to Fixya


Remove the vent line from the rear and try the dryer.
If it heats then that means there is a clog or kink in the vent line blocking the vent air from exiting which will stop the dryer from getting hot!
If not then it's another one of these problems.

Defective Ignitor (Gas Only)
When heated the ignitor used on your gas dryer must obtain a specific high temperature
in order to activate the flame sensor. This ignitor is fragile and susceptible to cracking.
A hairline fracture that is barely visible to the naked eye is enough to change
the resistance of the ignitor to a point that is will not work properly.
You can test the resistance of your ignitor. You should get a reading of 50-400 ohms of
resistance.

If the ignitor gets hot and then goes off after about 10-15 seconds and there is
no ignition, the problem is probably not the ignitor. It is most likely the gas valve
coils that are defective.

If the ignitor comes on and stays on, it is the flame sensor that is defective.

If the ignitor is not getting hot it could also be one of the thermostats that is defective.
The power for the ignitor is passed from the timer, through all of the thermostats,
limit switches and fuses to the ignitor. So if you are not getting power to the ignitor
during ignition, you should check the continuity of the individual thermostats and fuses.
DRYER DOES NOT HEAT



Defective Gas Valve Coil (Gas Dryer Only)

If the gas dryer will light once but will not relight until it cools down, it is likely the gas valve coils are faulty. These coils loose some strength when subjected to heat. When they become old, the addition of heat may be enough to prevent them from opening the gas valve when hot. However the coils still work when when cool.

An easy way to diagnose the coils when the burner is not lighting, watch the ignitor. If the the ignitor glows for 10 to 15 seconds but no flame is created, then the coils are faulty. If the ignitor is not glowing the problem is elsewhere.

Recent Customer Symptoms:
The dryer burner doesn't always come on when starting. If the burner does come on, once it goes off if won't come on again until the dryer cools down.



Defective Flame Sensor (Gas Dryer Only)
The flame sensor's job is to monitor the ignitor for sufficient heat
to ignite the gas. A properly operating flame sensor will pass a
continuity check under room temperature.

Common Symptoms
If the flame sensor is defective in the open position,
the ignitor will not get hot when the dryer is started.
However, if it is defective in the closed position the ignitor
will get hot, but the flame sensor will not allow the flame to ignite.
In this case, the ignitor will usually stay hot for a long period of
time.



Defective Thermostat
The thermostats are responsible for maintaining the proper temperature
in the dryer. Check the exhaust temperature of the dyer and if the
temperature is above 150 degrees, you will most likely need to change
the operating thermostat.

The thermostat can also fail in the opposite mode.
It can prevent the element from heating at all.
A failed continuity check at room temperature will verify this condition.

There are some special thermostats that are single pole double throw.
These thermostats are often used to control the timer when set to the
Automatic Dry cycle. If the dryer timer will advance in the Timed Dry
cycle but not the Automatic Dry cycle, then the thermostat could be the
problem.


Defective Thermal Fuse
The thermal fuse is in series with one leg of power to the motor.
If the fuse is open (no continuity) the motor will not run.

Location:
The thermal fuse is located in different locations according
to the model and brand of dryer.

Solution:
Check the thermal fuse for continuity with a volt/ohm meter.
If it is open, it will need to be replaced






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