View Full Version : Low Ambient Controls
08-22-2004, 12:42 AM
Just curious, how do you guys setup a fan cycling control on a small R22 system? I've seen some of the preset switches that cut in at 270 and out at 190. Personally, I think that's way too much swing and you sometimes end up with flash gas before the fan comes on. I've been using the adjustable controls set to about a 240 cut in and a 40 psi deferential. Ends up bouncing the fan on and off a lot, but it's better for the compressor and the metering device.
I know a VFD is best, but they are expensive and a lot of them require a ball bearing motor - just not worth it for a little 2 ton split system. And you still need a positive cut-off below a certain point, which a lot of them don't provide.
Two controllers are among my favorites, on the cheap it's the ICM fan speed controller, about the same price as a cycling switch and can be used on a sleeve bearing motor. My old reliable is the Johnson P66, functional, reliable, okay it does cost a few dollars but quality does.
08-22-2004, 08:25 AM
Who sells the ICM? Can it actually completely stop the fan if it gets really cold?
08-22-2004, 12:08 PM
Johnson P66 with a ball bearing motor.
08-22-2004, 03:26 PM
Penn 66 or Johnson controller that operates on head pressure not temperature. Make sure you have a txv valve or you will have problems in the winter. Stay away from the cheap hoffman and fan cycling based on temperature.
08-22-2004, 06:03 PM
totaline parts (carrier) carries a motormaster type variable speed controller and is setup for sleeved or nonsleeved motors and they are just a little more than the p66.
Depends were you are for availability of ICM, on the East coast I could get them from R.E. Michel or United Refrigeration. Here in the mountain states from C.D. Jones. Definitely the Johnson P66 is the best, but you do need a ball bearing motor. The ICM is functional, works off COIL temp and to set it right you have to play with the sensor location, but it will shut off the fan. Once again, on the cheap it works. With low ambient you should always have a TXV but to each thier own.
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