Heating Fan works but no hot air, I have gas heat, I was able to see a intermitten sparks coming from the ignitor

my first impression is that the filters are too dirty and they caused the high limit to trip. needs serviced.

mounted on top of the gas vavlve is black electrical coils when energized it opens the gas valve,if one of the coils are defective it wont open and let the gas thru,its hard to test the coils so most repairmen just replace them all

It should only do that a few times then lock out necessitating reset by cycling the power at the furnace switch or at the t-stat. More than likely your hot surface ignitor is defective. Sequence should be something like this: Call for heat, combustion air fan initiates and blows for 30 seconds during a 'pre-purge' condition, then a relay clicks to energize the hot surface ignitor. If it does not ignite the flame within a few seconds, usually around 5 or 6 seconds, the ignitor relay clicks again and drops it out.

The flame sensing rod has to see flame to rectify the ground signal to the circuit board very quickly or else raw gas would continue to dump into the heat chamber. After the HSI relay drops out on flame failure the combustion air fan continues to run for a post purge cycle to purge the heat exchanger of any unburnt fuel before the sequence is initiated again.

Unplug the ignitor molex plug. It'll be within a few inches of the HSI itself. Insert a voltage test meter set to read 120 volts into the molex plug going TO the ignitor. Re-establish the call for heat, wait for a cycle of the relay clicks and steadily watch the meter. If the ignitor is bad, you should see 120 volts at the connection you are plugged in to AFTER the 30 second pre-purge. Watch closely, you may only have a 6 second window to see it because it will drop it out on flame failure.

Of course there are other issues that could be possible, but this is the most likely. If you do determine the ignitor is bad and you obtain a replacement DO NOT TOUCH the portion of the ignitor that glows (to ignite the gas) during assembly !!!! The oil from your skin will shorten the life expectancy TREMENDOUSLY.

If you suspect its the ignitor? The hot surface ignitor is powered by 120v. Inspect ignitors' hot surface for cracks or burnt spots. Uplug ignitor from board. Cycle heat on and verify 120v to the ignitor at the cannon plug on the board where the ignitor plugs in. If you have the voltage then replace the ignitor. If not, you'll need to verify all other circuits are working before condemning the board. Work safe and at your own risk! Hope this helps!

Hi,

Most modern dryers use a hot surface ignitor...

If you are having problems with your gas dryer not heating the most common problem is that the ignitor goes bad. Even though it glows sometimes 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 different things that can go wrong causing the dryer not to heat.

check out this electric no heat tip...

heatman101

I find that quite often the ignitor is out of alignment or the glass window is covered with lint.
a gas dryer blows air through a burner assembly to heat the air. The burner assembly consists essentially of a gas valve, ignitor and a flame sensor. If any part of the burner assembly malfunctions, the result will be low or no heat and slow drying of the clothes.
There are two common styles of ignitors, glow ignitors and spark ignitors. The ignitor ignites the gas either by heating up and glowing, or by sparking. If the ignitor fails, the dryer will not heat.

The easiest way to check the ignitor is to observe it. Remove the small access panel in front, select a high temperature setting and start the dryer. Watch the burner assembly, shortly after starting the dryer the ignitor should begin to glow or spark. If you see it glow or spark, then the ignitor is working.

the fan you hear come on at a call for heat is most likely just the inducer motor. the click you hear is probably the relay for the hot surface ignitor which should glow red, then in turn ignite the main burners. your going to have to determine if the ignitor is coming on. if it isnt the ignitor is bad and will need to be replaced. if it comes on and than shuts off after a few seconds the ifc board is probably at fault

The heat is regulated with a Klixon mounted next to the blower housing near the vent pipe so it can judge the temperature of the air coming out of the drum.Right next to it is a melting type fuse. If the dryer runs and gets too hot the fuse will melt.But the dryer will still run. So if the fuse is good(continuity) and the dryer control(cycle) thermostat is also good then you should have power going to the gas valve assembly when the machine is running unless the timer is in the no heat or wrinkle free/cool down mode. When the gas valve assembly is energized the flame sensor flame sensor mounted outside the burner chamber detects the heat from the ignitor. When the heat is very intense then the sensor shuts down the igniter
Igniter and that frees up the power so that the coils can be fully energised and open the gas gates. The gas comes out and hits the red hot igniter and you have ignition. It stays on for maybe 2 or 3 minutes or until the control thermostat is satisfied and shuts down power to the gas valve assembly.

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Therm calls for heat, enducer fan turns on, pressure switches closes, ignitor sparks, gas valve opens. If ignitor does not spark, it will go to try a few times then lockout. Do you have a led code on your control board, if so what is it blinking? Could be ignitor bad only..

these furnaces have a sequence of operation , 1 thermostats calls for heat,2 purge fan checks flue is open and not clogged ,3 checks to see if hot plate ignitor or spark ignitor is on 4opens gas valve 5 checks for flame and allows valve to stay open 6 checks for temperature rise and brings on fan , if any of the process is not there or interrupted trys 3 times and defaults to lockout , that is the best answer with out knowing what type you have , hope i helped