ELECTRICAL SHOCK HAZARD
Failure to follow this warning could result in personal injury
or death.
Disconnect 115-v electrical power before changing speed tap.
4. To change blower motor speed selections for heating mode,
remove blower motor lead from control HEAT terminal. (See
Fig. 31.) Select desired blower motor speed lead from 1 of the
other motor leads and relocate it to HEAT terminal. See Table
13 for lead color identification. Reconnect original lead on
SPARE terminal.
Follow this same procedure for proper selection of COOL
speed selection.
ADJUST BLOWER OFF DELAY (HEAT MODE)
The blower off delay has 4 adjustable settings from 90 sec to 180
sec. (See Table 14.) The blower off delay jumpers are located on
the furnace control (See Fig. 31). To change the blower off delay
setting, move the jumper from one set of pins on the control to the
pins used for the desired blower off delay. Factory blower off
delay setting is 120 sec.
SET THERMOSTAT HEAT ANTICIPATOR
When using a nonelectronic thermostat, the thermostat heat
anticipator must be set to match the amp draw of the electrical
components in R-W circuit. Accurate amp draw readings can be
obtained at thermostat subbase terminals R and W. Fig. 60
illustrates the easy method of obtaining actual amp draw. The amp
reading should be taken after blower motor has started and furnace
is heating. Connect ammeter wires as shown in Fig. 60. The
thermostat anticipator should NOT be in the curcuit while mea-
suring current. If thermostat has no subbase, the thermostat must
be disconnected from R and W wires during current measurement.
See thermostat manufacturer’s instructions for adjusting heat
anticipator and for varying heating cycle length.
For an electronic thermostat, set cycle rate for 3 cycles per hour.
Step 6—Check Safety Controls
This section covers the safety controls that must be checked before
the installation is complete. The flame sensor, gas valve, and
pressure switch were all checked in the Start-up procedure section
as part of normal operation.
CHECK PRIMARY LIMIT CONTROL
This control shuts off gas control system and energizes air-
circulating blower motor if furnace overheats. Recommended
method of checking this limit control is to gradually block off
return air after furnace has been operating for a period of at least
5 minutes. As soon as limit control has shut off burners, return-air
opening should be unblocked to permit normal air circulation. By
using this method to check limit control, it can be established that
limit is functioning properly and operates if there is a restricted
return-air duct or motor failure. If limit control does not function
during this test, cause must be determined and corrected.
CHECK PRESSURE SWITCH
This control proves operation of draft inducer. Check switch
operation as follows:
1. Turn off 115-v power to furnace.
2. Remove outer furnace door and disconnect inducer motor
from wire harness.
3. Turn on 115-v power to furnace.
4. Set thermostat to ″call for heat″ and wait 1 minute. When
pressure switch is functioning properly, hot surface igniter
should NOT glow, and control status code LED flashes a
Status Code 31. If hot surface igniter glows when inducer
Table 12—Gas Rate (cu ft/hr)
SECONDS
FOR 1
REVOLUTION
SIZE OF TEST DIAL
SECONDS
FOR 1
REVOLUTION
SIZE OF TEST DIAL
1
Cu Ft
2
Cu Ft
5
Cu Ft
1
Cu Ft
2
Cu Ft
5
Cu Ft
10 360 720 1800 50 72 144 360
11 327 655 1636 51 71 141 355
12 300 600 1500 52 69 138 346
13 277 555 1385 53 68 136 340
14 257 514 1286 54 67 133 333
15 240 480 1200 55 65 131 327
16 225 450 1125 56 64 129 321
17 212 424 1059 57 63 126 316
18 200 400 1000 58 62 124 310
19 189 379 947 59 61 122 305
20 180 360 900 60 60 120 300
21 171 343 857 62 58 116 290
22 164 327 818 64 56 112 281
23 157 313 783 66 54 109 273
24 150 300 750 68 53 106 265
25 144 288 720 70 51 103 257
26 138 277 692 72 50 100 250
27 133 267 667 74 48 97 243
28 129 257 643 76 47 95 237
29 124 248 621 78 46 92 231
30
120 240 600 80 45 90 225
31 116 232 581 82 44 88 220
32 113 225 563 84 43 86 214
33 109 218 545 86 42 84 209
34 106 212 529 88 41 82 205
35 103 206 514 90 40 80 200
36 100 200 500 92 39 78 196
37 97 195 486 94 38 76 192
38 95 189 474 96 38 75 188
39 92 185 462 98 37 74 184
40 90 180 450 100 36 72 180
41 88 176 439 102 35 71 178
42 86 172 429 104 35 69 173
43 84 167 419 106 34 68 170
44 82 164 409 108 33 67 167
45 80 160 400 110 33 65 164
46 78 157 391 112 32 64 161
47 76 153 383 116 31 62 155
48 75 150 375 120 30 60 150
49 73 147 367 124 29 58 145
Table 13—Speed Selector
COLOR SPEED
FACTORY-
SHIPPED
CONNECTION
Black High Cool
Yellow (When Present) Medium High Spare
Blue Medium Low Heat
Red Low Fan
White Common C
OM
Table 14—Blower Off Delay Jumper Positions
PINS 1 AND 2 2 AND 3 3 AND 4 4 AND 5
Time (in sec) 90 120 150 180
49
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