Owner's Manual for AM78-HC4V

Question edited for clarity.

Call 1-888-88EMGLO (1-888-883-6456)

Voltage and Circuit Protection Refer to the Voltage and Minimum Branch Circuit Requirements
under Specifications.
CAUTION: Certain air compressors can be operated on a
15 amp circuit if the following conditions are met.
• Voltage supply to circuit must comply with the National Electrical
Code.
• Circuit is not used to supply any other electrical needs.
• Extension cords comply with specifications.
• Circuit is equipped with a 15 amp circuit breaker or 15 amp
time delay fuse. NOTE: If compressor is connected to a circuit
protected by fuses, use only time delay fuses. Time delay fuses
should be marked "D" in Canada and "T" in the US.
If any of the above conditions cannot be met, or if operation of the
compressor repeatedly causes interruption of the power, it may be
necessary to operate it from a 20 amp circuit. It is not necessary to
change the cord set.

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You posted this in wrong section but I found a place with parts breakdown.

https://mastertoolrepair.com/air-compressor-parts-am39-hc2-am78-hc2-am39-hc4-am78-hc4-am39-hc4v-am78-hc4v-p-889.html

I just rebuilt my Emglo AM78 4CHV, new pressure switch, unloaded, check valve, aftercooler, and changed the #30 oil, It takes 4oz.
Runs like new after not cutting in/out correctly and purging air before reaching 125 psi. Kicked it down to 115 max psi via main spring setting. Don't need 125 for trim nailing and siding.
FYI don't use cheaper generic 125 psi pressure switch from Amazon!!
use Jenny M4-1247 (140-1074-01)

https://www.manualslib.com/
Get one

Here is a direct link to the Owner's Manual for your machine:

http://www.singerco.com/uploads/download/f3eff19dd0b1966512ad6a6bd24e3d8a74926fca.pdf

To view the Owner's Manual with Operating Instructions just use your mouse to click on the link, which is the underlined and highlighted text just above. This will open a new web browser page automatically for you and allow you to view the information at the website indicated and the contents of the Owner's Manual.

You may need ADOBE READER installed on your computer to read PDF documents.
You can download this free at WWW.ADOBE.COM if necessary.
Click on the DOWNLOAD ADOBE READER button on right side of the ADOBE home page when you get there, then follow the onscreen instructions to install the software on your computer.

I hope that was helpful to you, good luck and take care.

Joe.

The following link is to your Owner's Manual. You can download and print it for future reference.

http://www.danby.ca/cms/uploads/products/en_manual/DDR25E__DDR30E__DDR45E__DDR5011_manual_v3.pdf

Hope this helps you. Please let me know. Thanks.

I would suggest contacting Master Tool Repair, great web site to get information on these little machines, I know you can get owner manuals from them that may contain wiring diagrams with them.

Manual for the similar dewalt model is at www.dewalt.com, click on parts & service icon, then enter D55151. Or try clicking here: http://www.dewaltservicenet.com/documents/English/Instruction%20Manual/5135175-01,D55152,Elec.pdf This Dewalt compressor is one of many versions of the Old Emglo AM78 compressor. There are several other brands built with the exact same design such as the Senco line. For parts list of actual Am78hc4v go to mastertoolrepair.com. If you have questions or problems with this compressor please email, Good luck

The switch is bad, replace it, this should solve the problem.

Apparently there was a split in the company and many repair manuals are under the company Aerus. http://www.aerusonline.com/service/manuals.cfm