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Honeywell Smartfit Control Unit

My control unit has no power into it - how do I fix it? I have tried changing the fuse, examining all the connections, turning on/off but to no avail. Please Help

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You need to either call an electrician if your unable to, or do not have the knowledge to troubleshoot electrical circuits, or, get a multimeter and see that power is coming to the furnace/heater.

Reply back what type of heating unit you have (gas or electric), any other symptoms you've observed (including has the system ever operated before, and what changes may have been implemented to cause it not to operate) and the model, and we can be of more help to you.

Posted on Jan 22, 2009

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Hi, check the wire connections to make sure the Red wire is good and tight. This is only low voltage, so don't worry about getting zapped. If all wires are tight. you may have blown the control fuse at the indoor unit. Go to it with a good light, pull the panels and look for a circuit board that the thermostat wires connect to. Depending on the age, you should have a plug in fuse, like a auto fuse that will be a 3 to 5 amp fuse. See if it is blown. If your not sure, replace it anyway. Put the panels on correctly, and see if this solves your problem. If so, don't forget to rate me :)
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I had exactly the same problem. F4 code says the control valve has jammed --- but it hadn’t.

I ended up having to swap out the room controller and the base unit (I bought the pair since it was winter and I couldn’t ‘eff’ about)

On investigating (well, you have to don’t you?) I could find no obvious fault but did notice that a large electrolytic capacitor was across the actuator motor.

Since these things work by reversing the supply polarity to the motor to drive the actuator one way and the other it strikes me as strange that a polarity sensitive component, one that must be always connecter positive to positive, is used in the way that it is.

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