I thought we had a help me fix it sticky, but it was probably the old site where we nuked a number of child threads. Anyways....
(If someone cares to connect on the phone regarding this, please PM me your number)
It's my 30 y/o Bryant attic mounted air handler. Just started by blowing a fuse. Otherwise had no issues for 30 years.
1. Replaced the fuse, system ran and heated but short cycled > blew fuse > replaced
2. Tested cap > ok
3. Replaced fan motor on outside advice (single speed) > old one spun ok, didnt smell, test results didnt match Youtube.
4. System ran and heated but short cycled > blew fuse
5. Tested heat strip, visually inspected, replaced both heat thermostats because of inconsistent connectivity across terminals
6. Unable to fully test heat sequencer (27v in, couldn't get it engaged) > replaced
7. System ran and heated but short cycled - at this point I stopped before blowing another $10 fuse
8. Bypassed the wall T-stat, jumping red to white - system ran and heated - DIDNT short cycle - ran for 20 mins - blew fuse
9. I've got a full 240v to the unit, and the transformer and 27v out and down to the wall T-stat.
Argh! HVAC folks, what am I missing? I normally dont throw parts at problems without serious diagnosis, but this (seemingly) simple "too many amps causes my fuses to go bye-bye" is getting to me!
I've got a Greenleee clamp amp probe, DVOM, etc.
What kind of conditions are present to surge past 60 amps? I'm thinking I need to pull the breaker and look for bad news at the terminal connection.
What say ye?