Progressive EMS-HW50C unit
We have Porgressive EMS-HW50C about 1.5 years old and hardwired at the dealership into our new camper. Yesterday about 1:00 a.m. we heard this loud tapping noise. We thought we had a large rat in ou...
Forum Discussion
BillyandKris wrote:
It did this off and on for a couple of hours. Called Progressive and he asked for error read-outs. He said there was only electrical components and no moving parts inside it other than a switch.
That "switch" is a relay called a contactor and is what routes input power to the output when the sensing circuits detect no error - illustrated on Page 11 of your owner's manual. What is happening in your case is that input voltage is cycling slightly below, then above, the low voltage cutoff threshold of 104 vac, resulting in the relay chattering. I can duplicate that same situation myself if I try to run my A/C with my 2K genset - chattering as the EMS struggles to reconcile the signal but struggles because the load forces voltage to drop and cycle around the low voltage threshold. I sure wouldn't allow this to continue "for a couple of hours" as you did and wouldn't be surprised at all if the contacts were severely pitted, enough that the contactor should be replaced. The moment you noticed this you should have put the unit in bypass.
