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View Full Version : defrost issue on johnson board



SolarMike
12-08-2011, 06:39 AM
I hope this is the right place to post one of my first questions...gotta built the 15 posts.

Anyway, I bought a 4 ton 18 seer Hp for a client (Airease/FrasureJohnson group of products, York stuff I believe). I didn't buy an indoor coil and instead sized up a brazed plate condenser so i can heat water for floor heating. This is all working well except that it won't trigger a defrost.

I had a Ranco15 defrost control from an old HP and installed it but the original defrost board doesn't like the open contact where the Rv was connected. I was thinking of putting a resister across the RV pins to fool the control but I'm not sure this will work.

Has anyone had to make some adaptation to a board like this or know if the johnson board can be fooled by the resister?

ironpit
12-08-2011, 03:44 PM
sounds like you are wanting demand defrost. Do you have a board with time demand like an icp or goodman?

SolarMike
12-08-2011, 06:53 PM
Yes, it is a time demand defrost on a Luxaire HP. It is the only thing not working on this unit and i don't like the way the defrost is done on these unit anyway. I will eventually be programming my own control TAC, Reliable or KMC probably (not sure yet) so i really just need a timered defrost running on a bulb on the vapour line. The Ranco one I have is nackered. Anyone know what the current replacement is?