Submittal Sheet

ManualsBrandsJohnson Controls ManualsA28 Series Temperature ControlsA28 2-Stage Temp Control, 2 SPDT Switch Action, 120/208/240/277 VAC (30°F to 110°F)

Table Of Contents

Master Catalog 125

Temperature Controls Section A

Product Bulletin A28

Issue Date 0988

Code No. LIT-125130

A28 Series Two-Stage Temperature Controls

with NEMA 1 Enclosure

Application

These two-stage controls are

designed to cover a broad range

of general purpose operating

temperature control applications

in the refrigeration, air

conditioning and heating fields.

Two SPDT switches permit

independent control circuits.

Each switch may be wired for

"open high" or "close high"

action, as required. Models are

available with close differential

on each switch. A jumper

across the "common" terminals

is supplied as a standard

feature.

Models are available for fixed or

adjustable between stage

differential.

All Series A28 temperature

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.

Fig. 1 -- Exterior of the A28.

Knob range adjustment is

shown.

Features

• "Repeat" accuracy which is

unaffected by barometric

pressure and cross ambient

temperature problems.

• Dependable single-pole,

double-throw snap acting

contacts in dust protected

enclosure.

• Special close differential

models available for critical

requirements.

Range and Bulb Specifications

Specifications

Summary of content (4 pages)

PAGE 1
Master Catalog Temperature Controls Section Product Bulletin Issue Date 125 A A28 0988 A28 Series Two-Stage Temperature Controls with NEMA 1 Enclosure Application These two-stage controls are designed to cover a broad range of general purpose operating temperature control applications in the refrigeration, air conditioning and heating fields. Two SPDT switches permit independent control circuits. Each switch may be wired for "open high" or "close high" action, as required.
PAGE 2
Controls may be supplied for immersion applications for use with a closed tank connector or with a bulb well assembly. A low cutout stop, which can be set in the field, is an integral part of the control. Optional Constructions Ambient Compensation Available at extra cost. Fig. 2 -- Interior view showing high temperature (stage) and low temperature (stage) switches. General Description Controls are compact with nonadjustable differential on each switch.
PAGE 3
. Between-stage differential (nonadjustable models only). Type number (see Type Number Selection). 4. Capillary length, if other than 6 feet (1.8 m). Range required. 5. Packing nut assembly or bulb well, if required. Ordering Information To order, specify: 1. 2. 6. Specify type of range adjustment if other than knob adjustment. Repairs and Replacement Field repairs must not be made. For a replacement control, contact the nearest Johnson Controls wholesaler. Fig.
PAGE 4
Fig. 10: Typical wiring diagram of a refrigeration compressor with single-stage unloader. Two compressor packages may be sequenced with the same circuit. Performance specifications appearing herein are nominal and are subject to accepted manufacturing tolerances and application variables. UL Guide No. XAPX File No. E6688 CSA Class No. 4813 02 File LR948 Controls Group 507 E. Michigan Street P.O. Box 423 Milwaukee, WI 53201 4 A28 Product Bulletin Printed in U.S.A.