Johnson Controls A19ZBC Series Service manual

FANs 121, 125
Temperature Controls Section A
Technical Bulletin A19ZBC
Issue Date 1291
© 1991 Johnson Controls, Inc. 1
Code No. LIT-121071
Part No. 996-460
A19ZBC Type
Temperature Control
Application
The A19ZBC is used for general
purpose operating temperature
control applications. The control
has a single-pole, double-throw
contact unit and a temperature
range of 0 to 70°F (-15 to 25°C).
A packing nut assembly, Part
No. FTG13A-600R, (Fig. 2) and
a bulb well No. WEL14A-602R
(Fig. 3) for immersion
applications are available and
are ordered separately, if
required.
All Series A19 controls are
designed for use only as
operating controls. Where an
operating control failure
would result in personal injury
and/or loss of property, it is
the responsibility of the
installer to add devices
(safety, limit controls) or
systems (alarm, supervisory
systems) that protect against,
or warn of, control failure.
Installation
When provided, follow the
equipment manufacturer’s
instructions. If instructions are
not supplied, follow the
instructions in this sheet.
!
CAUTION: Do not dent or
deform the sensitive bulb of
this control. A dent or
deformation will change the
calibration and cause the
control to cycle at a
temperature lower than the
dial setting.
Mounting
When installing the control, use
the mounting bracket as a
template and mark the location
for the two mounting screws.
Drill or punch two holes and start
the mounting screws. Place the
slot in the bottom of the bracket
under the head of the lower
mounting screw. Position the
control so the top screw is in the
top slot. Tighten both screws. It
is not necessary to level the
control except for appearance.
For closed tank applications
without a bulb well, use the
FTG13A-600R packing nut.
(See Fig. 2.) Put parts over the
support tube section of the
element and place the bulb in
the tank. Install the 1/2 in. NPT
adapter in the tank opening and
tighten. Screw the packing nut
with the retaining washers and
packing into the adapter as
shown in Fig. 2.
!
CAUTION: Turn Off the
liquid supply and relieve the
pressure before installing or
removing the bulb or bulb
well.
For applications requiring a bulb
well, install the bulb well in the
tank opening. Remove the
bushing from the bulb well and
slide the bushing over the
capillary. Insert the bulb into the
bulb well and replace the
bushing. Push the bulb into
position in the bottom of the well.
Tighten the set screw in the
adapter end to hold the bulb in
position.
Fig. 1 -- A19ZBC Temperature
Control. Note the mounting
bracket on the back of the case.

2 A19ZBC Technical Bulletin
Wiring
!
WARNING: Disconnect the
power supply before wiring
connections are made to
avoid possible electrical
shock or damage to the
equipment.
Make all wiring connections
using copper conductors only,
and in accordance with the
National Electrical Code and
local regulations. See Fig. 4 for
terminal identifications and
contact action.
Note: Use the terminal screws
furnished (8-32 x 1/4 in. binder
head). Substitution of other
screws may cause problems in
making proper connections.
Adjustments (See Fig. 5)
Set the cut-in point by turning
knob “A” to the desired setting.
Rotate pointer “B” to the desired
cutout setting (differential
adjustment).
Checkout Procedure
Before leaving the installation,
observe at least three complete
operating cycles to be sure that
all components are functioning
correctly.
Repairs and Replacement
Field repairs must not be made.
For a replacement control,
contact the nearest Johnson
Controls distributor.
Controls Group
507 E. Michigan Street
P.O. Box 423 Printed in U.S.A.
Milwaukee, WI 53202