I have a Honeywell System. Back in November of 2014, I replaced the Circuit Board with one by Honeywell from Amazon (1014460). The blower motor was replaced over 2 years ago. Last month, I have replaced the Transformer. (No part # available at time of writing). I also replaced the cap on the board as well. (97F9002). My thermostat is about 5 years old. All caps for my a/c system are no older than 2 years old.
When I switch from Heat to AC, my circuit board fuse immediately pops. I am unable to use either until the fuse is replaced. I haven't tried replacing the circuit board fuse and putting it on AC to see if the AC would kick on that way. However, I haven't been able to determine why the fuse keeps blowing. Nothing was replaced last year and it worked great during the summer.
Any suggestions to try for troubleshooting? (See below for another suggestion)
Research: All the research I have found regarding my issue tends to be the other way around. People seem to have the issue with AC to Heat. However, I want to test to see if it is my thermostat as that has been suggested to others. How would I test if that is a possibility?
BRAND ICP Model N8MPNO75B12A1
Transformer 44504 jard 4031f