44
Rev. 2
PRODUCT DESIGN
ADJUST
NORM
( )
+
(-)
TEST
HEAT
A
B
C
D
COOL
A
B
C
D
Speed Tap Adjustments
Note: The heating speeds must be within the specified rise
range. Refer to the
BLOWER PERFORMANCE section of
this manual or
SPECIFICATION SHEET for this unit for tem-
perature rise settings.
2. If “G” from the thermostat is connected to “G” on the air
circulating motor interface board (Thermostat Wiring Fig-
ure C), the continuous fan speed will be 75% of the cool-
ing fan speed selected. The cooling fan speed can be
selected using the COOL and ADJUST taps on the air
circulating motor interface board. Refer to previous Speed
Tap Adjustments figure ). Refer to
BLOWER PERFOR-
MANCE section of this manual or the SPECIFICATION
SHEET for speeds.
Depending on the heating input of the furnace and the ca-
pacity of the cooling system, one continuous fan speed may
be preferable to the other. The lower the continuous fan
speed, the lower the electrical consumption. When using
an electronic air cleaner, make sure the continuous fan
speed’s CFM is within the CFM range listed for the elec-
tronic air cleaner.
Note: For two-stage heat only (no cooling) applications, the
continuous fan speed may be increased by jumpering “Y” to
“G”. Thermostat must have a ”G” terminal to make use of
this feature.
AIR CIRCULATION FAN TIMING
Single Stage GUI_ /GCI_ and Two Stage GUIS/GCIS
Furnaces
All items in this section refer to the air circulation blower,
not to the induced draft blower. The timing sequence for the
induced draft blower is not adjustable.
When a call for cooling occurs, the circulation fan will come
on. It will remain on for 45 seconds after the call for cooling
ends. This fan timing is not adjustable.
During normal heating operation, the air circulation blower
will come on 37 seconds after the gas valve opens. This
timing is not adjustable.
As shipped, the circulation blower will remain on for 90 sec-
onds after the gas valve closes. If desired, this timing may
be adjusted. The following figure illustrates the adjustment
pins or switches, which are located near the low voltage
terminal strip.
60
Second
Delay
12
ON
OF
F
B1
B2
B3
B4
90
Second
Delay
12
ON
OF
F
B1
B2
B3
B4
120
Second
Delay
12
ON
OF
F
B1
B2
B3
B4
180
Second
Delay
12
ON
OF
F
B1
B2
B3
B4
Style A
Style B
Heating Fan Off Adjustments
GUIV Variable Speed, Two Stage Furnace
All items in this section refer to the air circulation blower not
to the induced draft blower. The timing sequence for the
induced draft blower is not adjustable.
Cooling Fan Timing
The cooling system may be attached in one of two ways.
The following will explain the two possible operations:
If “Y” from the thermostat is connected to “Y” on the Two-
stage Integrated Furnace Control (Thermostat Wiring Figure
B), then the following on and off sequences will occur.
100 %
50 %
Cooling
Speed
X
0
5
35
X
+45
X
+75
Time
(sec)
Call
For Cool
Call
Satisfied
Air Circulator Blower Operation
Cooling On Delay:
Cooling On Ramp Up:
Cooling Off Delay:
Cooling Off Ramp Down:
5 seconds
30 seconds
45 seconds
30 seconds
