Replaced igniter in gas dryer,it ran about 12 loads and now doesn't heat again. took out igniter and it seems fine

Hello there and welcome to fixya there are several things that could make this dryer not heat up
Here are the most common things

Thermal Fuse

If the dryer doesn\'t heat, but the drum
turns, check the thermal fuse(s). The thermal fuse protects the dryer
from overheating and helps to prevent fires. If the thermal fuse is
blown, it will have to be replaced.




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Gas Valve Solenoid

The gas valve has two or more electric
solenoids which open the valve to let the gas flow into the burner
assembly. If the dryer doesn\'t heat one or more of the solenoids may be
defective. If the igniter glows for 90 seconds but the burner flame
doesn\'t light, replace these coils as a set.


Dryer Igniter


If the dryer doesn\'t heat, the igniter might
be burned out. Check the igniter for continuity with an ohm meter. Dryer
igniters burn out over time, similar to a light bulb.

Heating Element

The heating element on an electric dryer can
burn out over time. If the dryer doesn\'t heat, the element should be
checked for continuity. The heating element cannot be repaired and must
be replaced if defective.

Heating Element Assembly

the heating element assembly on an electric
dryer can burn out over time. If the dryer doesn\'t heat, the element
assembly should be checked for continuity. The heating element assembly
cannot be repaired and must be replaced if defective.

Flame Sensor



Gas dryers have a flame sensor to detect the
heat given off by the flame. If the dryer doesn\'t heat, the flame sensor
might be defective. Check the flame sensor for continuity. This is not
as common as a burned out igniter or thermal fuse.


High Limit Thermostat


Although not common, if the dryer doesn\'t
heat the high limit thermostat can be defective. It can be checked for
continuity. If the thermostat is "open" the dryer doesn\'t heat.


Cycling Thermostat




The cycling thermostat regulates the
temperature of the air in the dryer. If the dryer doesn\'t heat it may be
caused by a defective cycling thermostat. This is not common.


Main Control Board

The main control board is normally not at
fault when the dryer doesn\'t heat. Check all of the other components in
this troubleshooting guide before replacing the main control board. The
main control board cannot be tested easily and must be replaced if it is
defective.


Timer
The timer is normally not at fault if the
dryer doesn\'t heat. In many situations where timers are replaced they
end up being returned. Check all of the more common components in this
troubleshooting guide before replacing the timer

see this causes and use the common sense.God bless you
If your dryer doesn't heat, check these: Igniter Gas valve coils Thermal fuse Igniter Modern gas dryers use an electric igniter to ignite the gas from the gas valve. When it's working properly, the igniter glows bright orange. When it burns out, the dryer tumbles but there's no heat because the gas can't ignite. When the igniter burns out, you need to replace it. If the igniter is held by a tension bracket, you very well may need to replace the bracket too. To determine if the igniter is burned out, watch the part testing video at the bottom of this page. The igniter is inside the dryer housing, near the bottom front, usually in a cone-shaped metal tube (the force cone). It's about 2 inches long. It's mounted to the far end of the burner tube, and it has two wires attached to it--or to the tension bracket, if there is one. Gas valve coils Watch the igniter. Does it glow bright orange, then shut off without igniting the gas? (When the gas ignites there's a large blue flame.) If so, there may be defective coils on the gas valve. Mounted on the top of modern gas valves, there are black electrical coils. The coils, when energized, open the gas valve. If one or more of the coils are defective, the valve doesn't open and the gas cannot ignite. Because it's often difficult to properly test the coils, it's usually best to replace both (all) of them at the same time. Thermal fuse On many dryers, there's a thermal fuse (a heat-sensitive fuse that blows if the dryer overheats) mounted to the exhaust duct inside the back cover panel. The fuse is about an inch long. It's usually embedded in black resin and mounted in a white plastic housing. If the fuse has blown, it has no continuity. When this happens, your dryer either just stops heating, or it doesn't work at all. Be sure to inspect the venting/heating system before replacing the fuse to put the dryer back into operation. (You can't re-set this type of fuse.) To determine if the thermal fuse has blown out, watch the part testing video at the bottom of this page.

its either the hi-limit switch is weak on the burner tube,or the gas valve coils on the gas valve are weak and can no longer keep the gas valve open to supply gas,if they appear warm after operation they are most likely bad

Hi,If you are having problems with your gas dryer not heatingthe most common problem is that the ignitor goes bad. Even though it glowssometimes it is still not working properly.if you dryer is gas check out this gas no heat tip....If you have an electric dryer, you can have many differentthings that can go wrong causing the dryer not to heat. check outthis electric no heat tip...

heatman101

any of these simple items could be your problem, check it out http://www.partselect.com/dryer+dryer-wont-heat+repair.htm

This happened to me. Turned out it was a gas valve fracture which had to be replaced by the gas company. That's if you have a gas dryer

Those coils are probably getting hot and quitting then after a long time they cool off and work some more then quit again.

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

Seems to be a problem with the bas valves....you shouldve seen them in front of ignitor...will show similar signs of ignitor. part#306106 AND 306105. come off easily with a few screws and just slide over valve assembly.

it seems you have a lot of knowledge,,,i ran the schemtic,,and the only thing i could see that could be,, bad thermistor,,or the microprocessor control went bad..keep me posted onthejob

on gas dryers there are two coils on the burner assy. (small black cylinder with two wire haness) one opens initially to allow gas for ignition after that the flame sensor will allow the secondary to open for continuous flame i suggest replacing them both