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4hal
25-05-2010, 01:06 PM
I have a 3 ton Comfortmaker R-410A Split System Heat Pump. The installation guide says: "The defrost thermostat is factory installed on a short tube stub extending from the coil end plate . . .confirm that the thermostat is securely fastened in place on the tube stub."
Between the two service valves, there is a 1/4" tube stub, about four inches long. It's capped. There's no defrost thermostat attached. The illustration shows a stub that doesn't resemble mine. It shows the thermostat with two wires and no indication of where they connect.
Since it's supposed to be factory installed, could it be inside the case and the stub is there for field testing the low side temperature? There is no electrical wiring or ladder diagram in the guide. Disappointing and confusing. Any suggestion appreciated.

Brian_UK
25-05-2010, 11:34 PM
Probably inside the casing and fixed to the end of the condenser coil.

If you lift the lid or the electrical cover plate you might find a wiring diagram.