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Your problem
is:
The LED indicator
light is not coming on
The
cells never spark
Power box
switch is ON
Door is tight in
place
Blower is ON |
- Verify
Power is Present.
Unplug the power box
and operate a drop-light in the 3-prong
receptacle verifying an acceptable voltage and
current.
- Check
for Shorted Cells
A shorted cell can
prevent the indicator light from coming on.
Remove both cells, with door back in place
operate without the cells. If the unit now
appears OK with indicator LED ON, then the cells
have a problem.
- Operate without cells
- Check cells for broken wires
- Check cells for bent plates
- Check with one cell at a time (align cell
with contact)
- Replace
or Repair Power Box.
If the power box is
plugged in to 120v and the LED indicator still
does not light without the cells (blower must be
running), then the problem is in the power box.
- Check the on/off switch, 3-Prong
Connectors, and wiring.
- Bypass the Air Flow Sensor (AFS), The AFS
is a switch that closes when air flow is
present. By-Passing the AFS will force on the
power supply, See AFS By-Pass section below.
- An LED problem is not likely if the cells
never spark. The LED will not light if its blue
and white wires are crossed.
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When there is no air flow and the SST is
turned on, it is normal operation for the green
LED to come on for 10 seconds and then turn off.
If this behavior exists with the blower running,
then inspect the thermister orifice for a
clog.
The AFS uses a thermister to sense air flow,
see photo. The thermister heats up to 120
degrees and when cooled with air flow, the
circuitry switches the power on. The vacuum in
the duct draws air through the orifice and cools
the thermister.
To bench test the power box, we use the setup
shown below. Our fan draws a vacuum near the AFS
orifice and we move the fan away until the green
LED goes out. We compare this sensitivity to our
test unit.
The most simple test is to just blow at the
orifice with a straw. Use a mirror (shiny
galvanized sheet metal) to watch the LED on the
other side of the power box. The LED will turn
on as soon as you blow, and go off with in a
second after stopping. A hair dryer would also
work. |
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A thermister is a device that changes
resistance with temperature change.
Beware of electrical shock. The
contact
and rivets are live at 6200
volts.
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To test the power box without air flow
requires by-passing the air flow sensor (AFS).
The AFS is a switch that closes when air flow is
present. The 120v power passes through the AFS
switch and on to the power supply.
The AFS connects or disconnects the neutral
side of the 120v. The 120v neutral wire passes
through the AFS and then on to the power supply.
The neutral wire enters the AFS on the white
wire, and exits the AFS on the white/brown
wire.
By-passing the AFS applies the 120v power
directly to the power supply. This will cause
the power supply to operate with or without air
flow.
The AFS by-pass can be used to isolate a
problem with the power supply or AFS. If the
power supply operates with the AFS by-passed,
then there is a problem with the AFS and not the
power supply. The collector cells need not be
connected.
Photo below shows by-passing the AFS.
Disconnect the modular plug from the AFS and
then connect the white wire to the white with
brown stripe wire. We did this using the yellow
wire shown below. We used a 14 gauge wire
because if fit snug in the connector. This will
force on the power supply and the green LED will
light. |
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