No heat call, found the filter was plugged solid and coil.
With the blower door off Im bypassing the coil and the unit works.
I would assume that with the door on and the unit calling for heat 2 things would happen because of lack of air.
1- Air switch would not prove and heat strips would not energize.
2- Heat strips would energize and limit switch would open ( limit switch didnt not open when tested)
Its in a dark ceiling thats very tight and hard to work in, theres no tech data on site as far as schematics. I was able to locate the limit switches but not the air switch if there is one.
Carrier says unit has been obsolete since 1989
I have a call into the carrier tech line to see if I can get my hands on some data.
Tomorrow Im going back to the job to clean the coil, just trying to get more information.