Bryant FA4A - Manual (Page 10)

A U G / 1 4 / 2 0 0 8 / T H U 0 3 : 4 7 P M UTC TECH PUB F A X N o , 3 1 7 2 4 0 5 6 6 2 P . 0 1 0
2, Check output voltage of transformer secondary side SEC2
and SECl. Be sure transformer output is around 24 vac. If
tráíisfoTOjef output is zero vac and transformer is! receiving
correct input voltage (208v or 240v), then transformer
needs to be replaced with recommended transformer. If
transfoirtier output is 24 vaCj proceed to items 3 and 4,
3. Check Jow-voltage fuse shown in Fig. 6. If fuse is blown,
replace it. The transfortner cannot supply power to board
with fuse blown or loose. If fuse blows when unit has power
applied to it, the system most likely has 1 of the following
problems:
a. Check control circuit for a short or miswiring problem,
b. The maximui» load on transformer is 40 va. If load on
transformer is excessive, the low-voltage 5-amp firse
will blow to protect transfomicr. If load exceeds va
rating of transformer, a larger va rated transformer needs
to be installed. Check sequencers for excessive current
draw.
c. Check wiring of heaters. If a heater is miswirsd, fuse
may blow, if a heater is mis wired, correct miswiring.
4. Check Tl, T2, and T3 connections on primary side of
transformer. If they are not connected properly, low-voltage
terminal board cannot supply 24-v signal to energize fan
motor. If transformer is receiving correct primary voltage
but is not putting Out correct secondary voltage, transformer
needs to be replaced,
B, If Electric Heat Stages Will Not Turn On But Fan WIN
Turn On:
1. Check wiring of sequencers. Pay particular attention to
high- and low-voltagB wiring of sequencers.
2. Check plug wiring to make sure that it is wired correctly,
3. Check voltage to sequencer. Sequencer number 1 receives a
24-vac signal. If it is receiving correct voltage, cheek to see
if sequencer is closing. If sequencer is not dosing but is
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