Honeywell T8511G Installation Instructions Manual page 10

MICROELECTRONIC HEAT PUMP THERMOSTAT
TROUBLESHOOTING GUIDE (Continued)
Symptom
Thermostat minimum off-time is
Heating will not
activated.
come on.
(continued)
System selection is not set to
Heat.
O/B terminal configured
incorrectly
O or B terminal miswired
Cooling will not No power to the thermostat.
come on.
Thermostat minimum off-time is
activated.
System selection is not set to
Cool.
O/B terminal configured
incorrectly
O or B terminal miswired
System On Heating equipment is not
indicator is lit, but operating.
no heat is being
delivered.
a
Available on select models.
69-0961—4
Possible Cause
a
.
a
.
a
.
a
.
Wait up to five minutes for the system to respond.
Set system selection to Heat.
Check Installer Setup mode number 29 and reconfigure
correctly.
Check system description to determine whether changeover
should be energized in heat (B) or cool (O). Rewire if
necessary.
• Check that C terminal is connected to the system
transformer.
• Check for 24 Vac between C and R or RC and Y terminals.
— If missing 24 Vac:
— Check if the circuit breaker is tripped—reset the
circuit breaker.
— Check if the system fuse is blown—replace the fuse.
— Check if the system switch at the equipment is in the
Off position—set to the On position.
— Check wiring between thermostat and HVAC
equipment—replace any broken wires and tighten
any loose connections.
— If 24 Vac is present, proceed with troubleshooting.
• Wait up to five minutes for the system to respond.
• Enter Installer Setup mode number 33. Reconfigure
minimum off-time (if required).
Set system selection to Cool.
Check Installer Setup mode number 29 and reconfigure
correctly.
Check system description to determine whether changeover
should be energized in heat (B) or cool (O). Rewire if
necessary.
Verify operation of heating equipment in system-test.
10
Action