69-1339—2 G.H. Rev. 6-00
www.honeywell.com
Home and Building Control
Home and Building Control
Honeywell Inc.
Honeywell Limited-Honeywell Limitée
Honeywell Plaza
155 Gordon Baker Road
P.O. Box 524
North York, Ontario
Minneapolis, MN 55408-0524
M2H 3N7
W8635A EQUIPMENT INTERFACE MODULE
Printed in U.S.A. on recycled
paper containing at least 10%
post-consumer paper fibers.
Heating does not come
on. System on indicator
( =
heat)
displays.
Communication is not being
completed.
Heat load at W8635A is not
connected correctly.
End and repeat the call for heat. Check the Flash COM
OK LED on the W8635A EIM while the call is being
made.
If the Flash COM OK LED does not blink:
check communication Bus wiring.
If the Flash COM OK LED blinks:
check that 24 Vac is present at W1 terminal.
If 24 Vac is not present:
check R to Rh connection.
If the connection is good:
replace the W8635A EIM.
Cooling does not come
on. System on indicator
(
= cool) displays.
Communication is not being
completed.
Cool load at W8635A is not
connected correctly.
End and repeat the call for cool. Check the Flash COM
OK LED on the W8635A EIM while the call is being
made.
If the Flash COM OK LED does not blink:
check communication bus wiring.
If the Flash COM OK LED blinks:
check that 24 Vac is present at Y1 terminal.
If 24 Vac is not present:
check R to Rh to Rc jumper connection.
If the R to Rh to Rc connection is good:
replace the W8635A EIM.
“wait” is displayed and
the call for Cool has not
started.
Compressor protection is in
effect.
Compressor protection can be set from 0 to 5 minutes
to prevent compressor damage due to rapid cycling.
Wait until the compressor protection period expires.
To bypass compressor protection during the installation
phase, see the Installer System Test section.
2
nd
stage heat or cool
does not energize.
Stage configuration not set
correctly to match the number of
selected stages.
Cool load at W8635A is not
connected correctly.
Set the Stage configuration in Installer Setup for two
stages or heat and/or two stages of cool.
Check that 24 Vac is present at Y2 or W2 terminal. If
24 Vac is not present, all connections are good and the
thermostat is correctly configured, replace W8635A EIM.
Fan does not come on
with a call for electric
heat.
Electric heat setting is not
configured.
Fan load at W8635A is not
connected correctly.
Set Installer Setup No. 4 to 1 for electric heat.
Check that 24 Vac is present at G terminal. If 24 Vac is
not present, all connections are good and the thermostat
is configured, replace the W8635A EIM.
Table 7. Troubleshooting Guide. (Continued)
Symptom
Possible Cause
Action