In article , Donna Ohl, Grady Volunteer Coordinator wrote: [ ... ]
Describing the problem--the High Limit is being triggered; I believe that's the high pressure sensor you mentioned earlier. That means the fan is trying to blow air, but it's backing up. Another possibility is the motor overheating and triggering it's thermal protection switch, which will reset when the motor cools orr.
The motor isn't over heating, so it and the High Limit are working correctly, and the problem is that something is obstructing air flow downstream from the blower--like a coil full of lint and debris, which got that way due to the filter not being changed monthly like it's supposed to be.
What it cost to get the same basic answer your got from the first tech; the coil needs to be cleaned. Have whichever outfit will charge less do it.
Gary