AboutJ Cook Expertise With 25+ years experience, I am familiar with residential, commercial, and industrial HVAC equipment including but not limited to boilers, chillers, reciprocating and screw compressors. I am trained in all manners of control wiring.
Experience I currently have three HVAC licenses and Refrigeration license by the State of North Carolina. I have been in this field for over twenty years. I have been a service technician for a contractor and also worked at a state college in the repair and maintenance of steam lines and equipment. I am currently the Building Maintenance Superintendent for a municipality.
Question I have a existing 10, 3 phase, ac system with
strip heat. Problem is, transformer in outdoor
unit, every time when yellow wire (for compressor
contactor) is connected, the fuse reset on transformer trips. I have verified that the wire
is good, no shorts,etc. The wiring from cond.
is Red 24v, Blue-common, yellow, goes up to the a/h in bld. The wiring in bld./ stat is normal.
(stat R,Y,W,G) the yellow wire comes from stat
directly to cond./transformer. When connected,
trans. trips after approx. 3 sec. delay. Transformer is 480v primary, 24 sec. Any help,
PLEASE. What else to look for? or check?
Answer Hello Dave. Something in the control circuit is shorted, causing the transformer fuse to trip and save the transformer. Check the coil on the compressor contactor first. Turn off all power, take all wires loose on the contactor coil, and see if there is a short to ground on the coil, and if there is continuity of the coil. This is the most likely culprit. If this is not the shorted component, you can try removing the wires one at a time from each low voltage device, turn the power back on and it will not trip when the shorted device is out of the circuit. Thanks for asking, let me know, J
