Wiring Error Quick Reference Guide - nest Learning thermostat Installation And Configuration Manual

Wiring error quick reference guide

When Nest senses what wires have been connected to its base, it automatically configures its software for
the system type it detects. If it's a heat only system, Nest won't show any cooling options. If it's a heat
pump, Nest will know—and do a special test to check the orientation of the O/B wire.
If Nest senses a problem with the wiring, you'll get an error if the issue must be fixed before setup can
continue, or a note if it is not critical to fix during setup. Here's a breakdown of the errors and notes and
what they mean.
Specific troubleshooting help for wiring errors is available online at nest.com/support.
Error
number Description
E1 Common wire C required.
E2 No power wires detected.
E22
Rh or Rc wire is required.
E3 No power to Rc wire
detected.
E23
E4 No power to Rh wire
detected
E24
E5 No heating or cooling
wires detected.
E25
W1 or Y1 wire is required
E6 Too many wires detected.
E7 Y1 wire not detected.
Heat pump requires a Y1
E27
wire.
E8 Additional wire(s)
required. AUX/W2
E28
detected by itself.
E9 No power to C wire
detected.
E29
Nest Learning Thermostat installation & configuration guide
What's going on?
This wiring error may appear after installation when Nest can't get
power while the system is turned on. Nest's software should be
updated if this error appears
You'll see this error when either a Rh or Rc wire was not installed or
the Rh or Rc wire that was installed isn't powered.
You'll see this error if you've installed both an Rc wire and Nest isn't
electrically detecting it.
You'll see this error if you've installed both an Rh wire and Nest isn't
electrically detecting it
Nest cannot detect any wires inserted into W1 or Y1. At least one of
these is required.
This error indicates that the wiring combination you've installed is
no supported by Nest. Verify the actual wiring for the system and
remove at least one of O/B, W1, Y1 or AUX wires as appropriate.
Your Nest is physically detecting a wire in the O/B connector. This
connector is exclusively used for heat pumps which also require a
Y1wire to be attached.
Your Nest is physically detecting a wire in the AUX/W2 connector.
Supported configurations that use this connector also include a W1
wire or an O/B + Y1 wire.
Your Nest is physically detecting a wire in the C connector, but isn't
detecting any power to it.
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