. . a circuit diagram showing the proper connections. Circuit diagram. A circuit diagram is a drawing that shows electrical circuits and the various parts of circuits. The drawing usually shows the circuit elements as rectangles, as well as the connections between the circuit elements. The connections between the circuit elements are represented by wires.. . . 4. VACUUM PUMP OPERATING INSTRUCTION MANUAL. INCORPORATES THE CHARTED DIAGRAM ON PAGES 4-4A. Operating Instructions. This is a refurbished unit from HVAC, Inc. and it has been specifically upgraded to install a PSI hold-down switch. This unit has been completely inspected and upgraded for maximum reliability and efficiency. It is NOT a typical HVAC, Inc. unit. It has been cleaned, tested, and repaired to provide the customer with the best replacement in the industry. It is 100% guaranteed that your unit will perform to your expectations. WARRANTY. We are pleased to offer a warranty with each purchase. We will replace your unit, free of charge, if it fails to work properly in the first 30 days. This warranty does not apply to unit failures which are due to normal wear and tear, installation, maintenance or misuse. HVAC, Inc. offers a 5 year warranty for the entire unit (Excluding the Drive Motor, Control Box and Motor Enclosure) and 5 year warranty for the Air Damper. Refurbished units are not subject to the same testing, inspections and restorations performed on our new units. Item #: DV121229 01.01.2016 2.00.2017 3.00.2018 4.00.2019 5.00.2020 6.00.2021 7.00.2022 8.00.2023 9.00.2024 10.00.2025 11.00.2026 12.00.2027 13.00.2028 14.00.2029 15.00.2030 16.00.2031 17.00.2032 18.00.2033 19.00.2034 20.00.2035 21.00.2036 22.00.2037 23.00.2038 24.00.2039 25.00.2040 26.00.2041 27.00.2042 28.00.2043 29.00.2044 30.00.2045 31.00.2046 32.00.