U.S. General 66974 Set Up And Operating Instructions Manual

Brand: U.S. General

Model: 66974

Category: Air compressors

Type: Set Up And Operating Instructions Manual

U.S. General 66974 is a 3/4 HP Super Quiet Carry Frame compressor. It can be used for various applications, including inflating tires, powering air tools, and painting. The compressor features a 6-gallon tank and a maximum pressure of 125 PSI. It is also equipped with an oil-free pump, which means it requires no maintenance. Additionally, the compressor is designed to be quiet, with a noise level of only 70 dB. This makes it ideal for use in residential areas or other noise-sensitive environments.

3/4 HP SUPER QUIET

CARRY FRAME COMPRESSOR

66974

SET UP AND OPERATING INSTRUCTIONS

Distributed exclusively by Harbor Freight Tools®.

3491 Mission Oaks Blvd., Camarillo, CA 93011

Visit our website at: http://www.harborfreight.com

Read this material before using this product.

Failure to do so can result in serious injury.

SAVE THIS MANUAL.

contained herein may be reproduced in any shape or form without the express written consent of

Harbor Freight Tools. Diagrams within this manual may not be drawn proportionally. Due to continuing

improvements, actual product may differ slightly from the product described herein. Tools required for

assembly and service may not be included.

For technical questions or replacement parts, please call 1-800-444-3353.

SKU 66974 For technical questions, please call 1-800-444-3353. Page 2

SAVE THIS MANUAL

Keep this manual for the safety warn-

ings and precautions, assembly, operat-

ing, inspection, maintenance and cleaning

procedures. Write the product’s serial

number in the back of the manual near the

assembly diagram (or month and year of

purchase if product has no number). Keep

this manual and the receipt in a safe and

dry place for future reference.

IMPORTANT SAFETY

INFORMATION

In this manual, on the labeling,

and all other information provid-

ed with this product:

This is the safety alert

symbol. It is used to alert

you to potential personal

injury hazards. Obey all

safety messages that

follow this symbol to avoid

possible injury or death.

DANGER indicates

a hazardous

situation which, if not

avoided, will result in death or

serious injury.

WARNING

indicates a

hazardous situation which, if

not avoided, could result in

death or serious injury.

CAUTION, used

with the safety

alert symbol, indicates a

hazardous situation which, if

not avoided, could result in

minor or moderate injury.

NOTICE is used to

address practices

not related to personal injury.

CAUTION, without

the safety alert

symbol, is used to address

practices not related to

personal injury.

General Safety Warnings

WARNING Read all safety

warnings and instructions.

Failure to follow the warnings

and instructions may result in

explosion, re and/or serious

injury.

Save all warnings and

instructions for future reference.

Work area safety1.

Keep work area clean and well lit. a.

Cluttered or dark areas invite acci-

dents.

Do not operate tools in explosive b.

atmospheres, such as in the pres-

ence of ammable liquids, gases

or dust. Tools become hot which

may ignite the dust or fumes.

Keep children and bystanders c.

away while operating a tool. Dis-

tractions can cause you to lose con-

trol.

Electrical safety2.

Tool plugs must match the outlet. a.

Never modify the plug in any way.

Do not use any adapter plugs with

grounded tools. Unmodied plugs

and matching outlets will reduce risk

of electric shock.

Avoid body contact with grounded b.

surfaces such as pipes, radiators,

ranges and refrigerators. There is

SKU 66974 For technical questions, please call 1-800-444-3353. Page 3

an increased risk of electric shock if

your body is grounded.

Do not expose tools to rain or wet c.

conditions. Water entering a tool

will increase the risk of electric shock.

Do not abuse the cord. Never use d.

the cord for carrying, pulling or

unplugging the Compressor. Keep

cord away from heat, oil, sharp

edges or moving parts. Damaged

or entangled cords increase the risk

of electric shock.

If operating the Compressor in a e.

damp location is unavoidable, use

a Ground Fault Circuit Interrupter

(GFCI) protected supply. Use of

a GFCI reduces the risk of electric

shock.

Do not use an Extension cord with f.

this product.

Personal safety3.

Stay alert, watch what you are do-a.

ing and use common sense when

operating this Compressor. Do

not use this Compressor while you

are tired or under the inuence of

drugs, alcohol or medication. A

moment of inattention while operating

tools may result in serious personal

injury.

Use personal protective equip-b.

ment. Always wear eye protection.

Safety equipment such as dust mask,

non-skid safety shoes, hard hat, or

hearing protection used for appropri-

ate conditions will reduce personal

injuries.

Prevent unintentional starting. c.

Ensure the On/Off Lever is in the

off-position before connecting to

power source or moving the Com-

pressor.

Do not overreach. Keep proper d.

footing and balance at all times.

This enables better control of the tool

in unexpected situations.

Dress properly. Do not wear loose e.

clothing or jewelry. Keep your

hair, clothing and gloves away

from moving parts. Loose clothes,

jewelry or long hair can be caught in

moving parts.

Only use safety equipment that f.

has been approved by an appropri-

ate standards agency. Unapproved

safety equipment may not provide

adequate protection. Eye protection

must be ANSI-approved and breath-

ing protection must be NIOSH-ap-

proved for the specic hazards in the

work area.

Tool use and care4.

Do not force the tool. Use the a.

correct tool for your application.

The correct tool will do the job better

and safer at the rate for which it was

designed.

Do not use the tool if the switch b.

does not turn it on and off. Any

tool that cannot be controlled with

the switch is dangerous and must be

repaired.

Disconnect the plug from the c.

power source of the Compressor

before making any adjustments,

changing accessories, or storing

tools. Such preventive safety mea-

sures reduce the risk of starting the

tool accidentally.

Store idle tools out of the reach of d.

children and do not allow persons

unfamiliar with the tool or these

instructions to operate it. Tools are

SKU 66974 For technical questions, please call 1-800-444-3353. Page 4

dangerous in the hands of untrained

users.

Maintain tools. Check for mis-e.

alignment or binding of moving

parts, breakage of parts and any

other condition that may affect the

tool’s operation. If damaged, have

the tool repaired before use. Many

accidents are caused by poorly main-

tained tools.

Use the tool in accordance with f.

these instructions, taking into ac-

count the working conditions and

the work to be performed. Use of

the tool for operations different from

those intended could result in a haz-

ardous situation.

Service5.

Have your tool serviced by a quali-a.

ed repair person using only iden-

tical replacement parts. This will

ensure that the safety of the tool is

maintained.

Air Compressor Safety Warnings

1.



area or towards a hot surface. Spray

area must be well-ventilated. Do not

smoke while spraying or spray where



parts - keep compressor at least 20

feet away from explosive vapors,

such as when spraying with a spray

gun.

Risk of bursting - do not adjust 2.

regulator to result in output pressure

greater than marked maximum pres-

sure of attachment.

Risk of injury - do not direct air 3.

stream at body. To reduce the risk of

electric shock, do not expose to rain.

Store indoors.

Do not use to supply breathing air.4.

-5.

pressor at people or animals.

Industrial applications must follow 6.

OSHA requirements.

Maintain labels and nameplates on 7.

the tool. These carry important safety

information. If unreadable or miss-

ing, contact Harbor Freight Tools for a

replacement.

Avoid unintentional starting. Prepare 8.

to begin work before turning on the

tool.

Do not leave the Compressor unat-9.

tended when it is plugged into an

electrical outlet. Turn off the Com-

pressor, and unplug it from its electri-

cal outlet before leaving.

This product is not a toy. Keep it out 10.

of reach of children.

WARNING: The brass components 11.

of this product contain lead, a chemi-

cal known to the State of California

to cause birth defects (or other repro-

ductive harm). (California Health &

Safety code § 25249.5, et seq.)

People with pacemakers should 12.

consult their physician(s) before use.

-

imity to heart pacemaker could cause

pacemaker interference or pacemak-

er failure. In addition, people with

pacemakers should:





on.



SKU 66974 For technical questions, please call 1-800-444-3353. Page 5

avoid electrical shock.



grounded. Ground Fault Circuit Inter-

rupter (GFCI) should also be imple-

mented – it prevents sustained elec-

trical shock.

Some dust created by power sand-13.

ing, sawing, grinding, drilling, and

other construction activities, contains

chemicals known [to the State of Cali-

fornia] to cause cancer, birth defects

or other reproductive harm. Some

examples of these chemicals are:



-

ment or other masonry products

-

cally treated lumber

Your risk from these exposures var-

ies, depending on how often you do

this type of work. To reduce your

exposure to these chemicals: work in

a well ventilated area, and work with

approved safety equipment, such as

those dust masks that are specially



particles. (California Health & Safety

Code § 25249.5, et seq.)

WARNING: Handling the cord on 14.

this product will expose you to lead,

a chemical known to the State of

California to cause cancer, and birth

defects or other reproductive harm.

Wash hands after handling. (Califor-

nia Health & Safety Code § 25249.5,

et seq.)

The warnings, precautions, and in-15.

structions discussed in this instruction

manual cannot cover all possible con-

ditions and situations that may occur.

It must be understood by the operator

that common sense and caution are

factors which cannot be built into this

product, but must be supplied by the

operator.

SAVE THESE

INSTRUCTIONS.

GROUNDING

TO PREVENT

ELECTRIC SHOCK

AND DEATH FROM

INCORRECT GROUNDING

WIRE CONNECTION:

Check with a qualied

electrician if you are in doubt

as to whether the outlet is

properly grounded. Do not

modify the power cord plug

provided with the tool. Never

remove the grounding prong

from the plug. Do not use the

tool if the power cord or plug

is damaged. If damaged, have

it repaired by a service facility

before use. If the plug will not

t the outlet, have a proper

outlet installed by a qualied

electrician.

Grounded Tools: Tools with Three

Prong Plugs

SKU 66974 For technical questions, please call 1-800-444-3353. Page 6

Tools marked with “Grounding Re-1.

quired” have a three wire cord and

three prong grounding plug. The

plug must be connected to a properly

grounded outlet. If the tool should

electrically malfunction or break

down, grounding provides a low

resistance path to carry electricity

away from the user, reducing the risk

of electric shock. (See 3-Prong Plug

and Outlet.)

The grounding prong in the plug is 2.

connected through the green wire in-

side the cord to the grounding system

in the tool. The green wire in the cord

must be the only wire connected to

the tool’s grounding system and must

never be attached to an electrically

“live” terminal. (See 3-Prong Plug

and Outlet.)

The tool must be plugged into an 3.

appropriate outlet, properly installed

and grounded in accordance with all

codes and ordinances. The plug and

outlet should look like those in the

preceding illustration. (See 3-Prong

Plug and Outlet.)

Symbology

Double Insulated

Canadian Standards Association



V~ Volts Alternating Current

AAmperes

n0 xxxx/min. 

(RPM)

SKU 66974 For technical questions, please call 1-800-444-3353. Page 7

SPECIFICATIONS

Electrical Requirements 120 V~ / 60 Hz / 5.9 A

Air Hose Connection

Outlet

1/4” quick coupler

(female)

Maximum Air Pressure 100 PSI

Air Tank Capacity 1.6 Gallons

Air Flow Capacity

1.3 SCFM @ 90 PSI

2.5 SCFM @ 40 PSI

2.9 SCFM @ 5 PSI

 

Motor 3/4 HP

 Oil less

UNPACKING

When unpacking, make sure that the

item is intact and undamaged. If any parts

are missing or broken, please call Harbor

Freight Tools at the number shown on the

cover of this manual as soon as possible.

INSTRUCTIONS FOR

PUTTING INTO USE

Read the ENTIRE IMPORTANT

SAFETY INFORMATION

section at the beginning of this

manual including all text under

subheadings therein before set

up or use of this product.

TO PREVENT

SERIOUS INJURY

FROM ACCIDENTAL

OPERATION:

Turn the On/Off Lever of the

Compressor to its “OFF”

position, press the Safety

Valve to release excess

pressure in the tank, and

unplug from its electrical

outlet before assembling or

making any adjustments to

the tool.

Note: For additional information regarding

the parts listed in the following pages,

refer to the Assembly Diagram near

the end of this manual.

SKU 66974 For technical questions, please call 1-800-444-3353. Page 8

Components and Controls

OPERATING INSTRUCTIONS

Read the ENTIRE IMPORTANT

SAFETY INFORMATION

section at the beginning of this

manual including all text under

subheadings therein before set

up or use of this product.

TO PREVENT

SERIOUS INJURY

FROM ACCIDENTAL

OPERATION:

Turn the On/Off Lever of the

Compressor to its “OFF”

position, pull the Safety Valve

to release excess pressure in

the tank, and unplug the

Compressor from its electrical

outlet before preparing for

operation.

Connect an air hose (sold separately) 1.

to the Quick Coupler (41). The air

hose must be rated to the intended

PSI and must be long enough to

reach the work area with enough

extra length to allow free movement

while working.

Pull the Safety Valve to make sure 2.

there is no residual pressure in the

tank.

Following the tool manufacturer’s in-3.

structions, connect the tool assembly

(sold separately) to the air hose and

close the in-line safety valve (part of

tool assembly) between the compres-

sor and the tool.

Plug the Compressor Power Cord 4.

into a grounded 120 V electrical

outlet. Do not use an extension cord

with this product.

5.

Allow the Air Compressor to build up 6.

pressure until it cycles off.

Adjust the air compressor’s Pressure 7.

Regulator (40) so that the air output

is enough to properly power the tool,

Quick

Coupler

(41)

Gauges and Controls:

Gauges

and

Controls

Drain Valve (43)

Handle

On/Off



(36)

Tool

Pressure

Gauge

(35)

Tank

Pressure

Gauge

(56)

Pressure

Regulator

(40)

Figure 1

Safety

Valve

(37)

SKU 66974 For technical questions, please call 1-800-444-3353. Page 9

but the output will not exceed the

tool’s maximum air pressure at any

time. Turn the knob clockwise to in-

crease pressure or counter-clockwise

to decrease pressure. Adjust the

pressure gradually, while checking

the Tool Pressure Gauge (35) to set

the desired pressure range.

The Air Compressor will cycle up to 8.

100 PSI before shutting off. It will

start to build pressure again when the

air pressure in the air tank drops to

58 PSI.

After the job is complete, move the 9.

-

tion.

Open the Drain Valve (43) to release 10.

pressure. Squeeze the Trigger of the

air tool to release pressure from the

line.

Disconnect the air hose and tool.11.

To prevent accidents, disconnect its 12.

power supply after use. Clean, then

store the tool indoors out of children’s

reach.

SKU 66974 For technical questions, please call 1-800-444-3353. Page 10

MAINTENANCE AND

SERVICING

Procedures not specically

explained in this manual

must be performed only by a

qualied technician.

TO PREVENT

SERIOUS INJURY

FROM ACCIDENTAL

OPERATION:

Turn the On/Off Lever of the

Compressor to its “OFF”

position, pull the Safety Valve

to release excess pressure in

the tank, and unplug from its

electrical outlet before

performing any inspection,

maintenance, or cleaning

procedures.

TO PREVENT SERIOUS

INJURY FROM TOOL

FAILURE:

Do not use damaged

equipment. If abnormal noise

or vibration occurs, have the

problem corrected before

further use.

Cleaning, Maintenance, and

Lubrication

BEFORE EACH USE,1. inspect the

general condition of the tool. Check

for loose screws, air leaks, damaged

air pressure related gauges, damage

to the Regulator or Shut Off Valve,

and any other condition that may af-

fect its safe operation.

AFTER USE,2. clean external surfaces

of the tool with clean cloth.

3. WARNING! If the supply cord of

this power tool is damaged, it must

be replaced only by a qualied

service technician.

PLEASE READ THE FOLLOWING

CAREFULLY

THE MANUFACTURER AND/OR DISTRIBUTOR







MANUFACTURER OR DISTRIBUTOR MAKES

ANY REPRESENTATION OR WARRANTY OF

ANY KIND TO THE BUYER THAT HE OR SHE







IN FACT, THE MANUFACTURER AND/OR





















SKU 66974 For technical questions, please call 1-800-444-3353. Page 11

Troubleshooting

Problem Possible Causes Likely Solutions

Compressor will

not run

No electrical power. 1.

No power to outlet. 2.

Thermal overload.3.

Check that unit is plugged in properly to the 1.

outlet.

Check power at outlet. If outlet is unpowered, 2.

turn off tool and check circuit breaker. If

breaker is tripped, make sure circuit is right

capacity for the tool and circuit has no other

loads.

Wait for engine to cool and motor to restart 3.

(approx. 15 minutes).

Motor hums but

does not run or

runs slowly

 1.

Defective valves.2.

Have the voltage checked with voltmeter by a 1.



2.

Overheating Poor ventilation. 1.

Compressor undersized for 2.

application.

Move the compressor to an area with better 1.

air circulation.

Check air requirements of tools.2.

Unit cycles on and

off too frequently

Excess amount of air used. Use a compressor with a larger air supply.

Compressor

operates, but with

low air output

Valve or regulator loose or 1.

leaking.

Valve or regulator damaged. 2.

Air tank not pressurized yet.3.

4.

Repair leaks. 1.

Have valve or regulator repaired by a 2.



Allow pressure to build.3.

4.

Incorrect pressure

gauge reading

Pressure gauge damaged. 

technician.

Compressor

vibrates

Rubber tank feet worn or missing. Replace.

Follow all safety precautions whenever diagnosing or servicing the

tool. Disconnect air supply before service.

SKU 66974 For technical questions, please call 1-800-444-3353. Page 12

Part Description Qty

1 Side Cover 2

2 1

3 1

4 Connect Rod 2

5 Piston Ring 2

6 Fasten Plate 2

7 Screw M6 x 16 2

8 Cylinder 2

9 Cylinder Seal Ring 2

10 Cylinder Cover Seal Ring 2

11 Cylinder Cover 2

12 Screw M5 x 25 12

13 O-Ring 4

14 Connect Pipe 2

15 Screw M4 x 6 4

16 Brace 2

17 Exhaust Valve 2

18 Valve Plate 2

19 Intake Valve 2

20 Metal Cushion 2

21 Right Fan 1

22 Crank 2

23 Bearing 6006-2z 2

24 Screw M6 x 8 4

25 Screw M5 x 20 2

26 Right Crankcase 1

27 Wire Ring 1

28 Bolt M5 x 152 2

29 Screw M5 x 120 2

30 Spring Cushion Ø5 4

Part Description Qty

31 Stator 1

32 Bolt 2

33 Rotor 1

34 Bearing 6203-2z 2

35 Pressure Gauge 1

36  1

37 Safety Valve 1

38  1

39 Connector Bolt 1

40 Regulator 1

41 Quick Coupler 1

42 Tank and Carry Frame 1

43 Drain Valve 1

44 Cushion 4

45 Screw 4

46 Capacitor Cover 1

47 Capacitor 1

48 Nut 4

49 Anti-Vibration Feet 4

50 Intake Pipe 1

51 Valve Pressure Cut-Off 1

52 Check Valve 1

53 Joint 1

54 Handle Cover 1

55 Air Filter 1

56 Pressure Gauge 1

57 Discharge Pipe 1

58 Screw M5 x 10 2

59 Washer 4

60 Screw M6 x25 4

Record Product’s Serial Number Here:

Note: If product has no serial number, record month and year of purchase instead.

Note: Some parts are listed and shown for illustration purposes only, and are not

available individually as replacement parts.

PARTS LIST

REV 09f

SKU 66974 For technical questions, please call 1-800-444-3353. Page 13

ASSEMBLY DIAGRAM

36 35

REV 09f

SKU 66974 For technical questions, please call 1-800-444-3353. Page 14

LIMITED 1 YEAR / 90 DAY WARRANTY

Harbor Freight Tools Co. makes every effort to assure that its products meet high

quality and durability standards, and warrants to the original purchaser that for a period

of one year from date of purchase that the tank is free of defects in materials and work-

manship (90 days if used by a professional contractor or if used as rental equipment).

Harbor Freight Tools also warrants to the original purchaser, for a period of ninety days

from date of purchase, that all other parts and components of the product are free from

defects in materials and workmanship. This warranty does not apply to damage due di-

rectly or indirectly to misuse, abuse, negligence or accidents, repairs or alterations out-

side our facilities, normal wear and tear, or to lack of maintenance. We shall in no event

be liable for death, injuries to persons or property, or for incidental, contingent, special

or consequential damages arising from the use of our product. Some states do not allow

the exclusion or limitation of incidental or consequential damages, so the above limita-

tion of exclusion may not apply to you. 





To take advantage of this warranty, the product or part must be returned to us with

transportation charges prepaid. Proof of purchase date and an explanation of the com-

-

ther repair or replace the product at our election or we may elect to refund the purchase

price if we cannot readily and quickly provide you with a replacement. We will return re-

paired products at our expense, but if we determine there is no defect, or that the defect

resulted from causes not within the scope of our warranty, then you must bear the cost

of returning the product.



which vary from state to state.

3491 Mission Oaks Blvd. • PO Box 6009 • Camarillo, CA 93011 • (800) 444-3353

U.S. General 66974 Set Up And Operating Instructions Manual

Brand: U.S. General

Model: 66974

Category: Air compressors

Type: Set Up And Operating Instructions Manual

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U.S. General 66974 Set Up And Operating Instructions Manual

U.S. General 66974 Set Up And Operating Instructions Manual

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