iaHVACguy
23-07-2009, 02:58 PM
Hello. I'm new here today and will try to make this brief while trying to include all info I can. Having a problem with nuisance #1 compressor "motor current" faults on this condensing unit. I have ruled out the motor protector and HP switch--verified by tattle-tales. Sometimes the contactors engage, sometimes not. Of course, if the contactors do not engage there will be no current read. Relay board 1 has been replaced. Have checked all connections. CT was replaced earlier. When the contactors energize, I've noticed that the motor current reading on the ISN display reads low and doesn't meet the required 15% minimum within 4 seconds; however, my amp meter tells me there is much more current draw on start up. So, contactors de-energize. Yesterday, I switched the current resistors around, after checking their connections. Compressor 1 started and made 67% current load according to ISN. As soon as compressor 2 started and amps ramped up, compressor 1 amps went down until it faulted. So, I am wondering if the problem lies within the main processor board. This has been an intermittent problem and I've been pulling my hair on this one. Thank you.