Did any check the temp across to see if it's dropping out on high limit. Do they witness the failure and begin checking the limit to see if it's open?

Unfortunately, they haven't witnessed the problem because it hasn't happened when they are here. Both speculated it could be the high limit. They questioned, though, if it was the culprit why the burners would kick back on immediately after either blowing out the pilot light or turning the gas valve off and back on -- which then triggers the electronic ignition that reignites the pilot and then the burners.

Are they right?

Thanks for the insight.

Third technician from another company speculated the ignition module is failing and could be replaced for $500. Here's his notes:

- Checked all wiring and connections
- Checked evaporator coil
- Cycled heat on and ran normally for 15 min
- Then the gas valve, which has been replaced, began to click internally
- Low voltage dropped to 16.2 a few times
- Pilot part did have 21.6 volts
- It did stop main burners momentarily while the pilot stayed on
- Blower is on high speed for heat

If there is one ...... Pressure switch.

I was told a bad pressure switch would cause the pilot to shut off. In my furnace's case, when the burners shut down, the pilot remains on, along with inducer. When it happens, it's my understanding that the voltage from the ignition module to the gas valve drops enough that it doesn't have enough juice to keep the valve open.