A Comprehensive Maintenance Guide: Addressing the 'Air Compressor not Building Pressure' Issue in Jinjing Brand 120HP Mobile Diesel Air Compressors

A Comprehensive Maintenance Guide: Addressing the 'Air Compressor not Building Pressure' Issue in Jinjing Brand 120HP Mobile Diesel Air Compressors


The Jinjing 120HP diesel air compressor, a staple in construction and industrial environments, is prized for its portability and diesel-driven efficiency.

A Comprehensive Maintenance Guide: Addressing the 'Air Compressor not Building Pressure' Issue in Jinjing Brand 120HP Mobile Diesel Air Compressors

A Comprehensive Maintenance Guide: Addressing the 'Air Compressor not Building Pressure' Issue in Jinjing Brand 120HP Mobile Diesel Air Compressors

jinjing air compressor

The Jinjing 120HP diesel air compressor, a staple in construction and industrial environments, is prized for its portability and diesel-driven efficiency. However, common concerns such as the air compressor not building pressure, alongside issues like startup difficulties, pressure drop, and oil contamination in the compressed air, often challenge users[1]. Addressing air compressor problems and solutions head-on is crucial for optimal operation, showcasing the importance of routine compressor service and air compressor maintenance[1].

In tackling these challenges, a thorough understanding of air compressor troubleshooting, including periodic maintenance, is vital. This involves navigating pressure loss, ensuring the air system functions correctly, and managing the compressor service to prevent situations where the air compressor won't build pressure. Our guide aims to dissect and offer solutions for these prevalent issues, leaning on air compressor maintenance to enhance longevity and performance[1].

Understanding Your Compressor's Manual

Understanding the intricacies of your Jinjing 120HP diesel air compressor is pivotal for ensuring its longevity and optimal performance. Here's a breakdown of crucial resources and components to familiarize yourself with:

  • Essential Resources:
    • Test Instructions: Provided directly by the manufacturer, these are your first go-to for understanding operational procedures [2].
    • Literature Library & Support: A comprehensive collection of documents is available, detailing everything from basic operation to troubleshooting [3]. For any queries or additional support, the sales and service locator can guide you to nearby service centers [3], and the parts order tracking system ensures you're always informed about your orders [3]. For direct assistance, Quincy's contact number is (251) 937-5900 [3].
  • Key Components:
    • Air Compressor Pump and Control System: Understanding these components is crucial for diagnosing pressure-related issues [4].
    • Motor/Engine Types: Familiarize yourself with the specific motor or engine powering your compressor, as this can affect troubleshooting and maintenance [4].
    • Pressure Control Devices: Knowledge of devices like the pilot valve and pressure switch is essential for managing system pressure effectively [4].

This foundation will aid in addressing any issues of air compressor not building pressure, ensuring a smoother, more efficient operation.

Routine Checks and Maintenance

In my journey with the Jinjing 120HP diesel air compressor, I've established a meticulous routine for checks and maintenance that ensures peak performance and longevity. Here's a breakdown of my approach:

Daily and Weekly Routine:

  • Daily Checks:
    • Verify oil and fluid levels in both the engine and compressor [14].
    • Drain any water from the fuel/water separator and fill the fuel tank [14].
    • Inspect for unusual noises, vibrations, air or oil leaks, and the condition of the air filter(s) [17].
  • Weekly Inspections:
    • Examine the condition of vibration pads, tighten bolts as necessary, and check belt tension [17].

Monthly and Quarterly Maintenance:

  • Monthly:
    • Perform safety valve operations check, change compressor oil, clean/change air filter, conduct pump up time test, and verify system controls functionality [17].
  • Quarterly:
    • Inspect air tanks for any signs of dents or leaks [17].

Semi-Annual and Annual Checks:

  • Every 250 hours:
    • Clean both the engine side and compressor side air filters [7].
  • Every 500 hours/Annually:
    • Replace air filters and conduct a thorough inspection of pressure relief valves by an accredited inspector [7][10].
    • Manually check pressure relief valves for correct operation and inspect hoses for any signs of wear or damage [10][11].

Adhering to this schedule not only addresses common compressor issues but also enhances safety and efficiency. Regular registration of the compressor ensures compliance and readiness for operation [3].

Changing the Oil

In my experience with the Jinjing 120HP diesel air compressor, timely oil changes are pivotal for maintaining its efficiency and preventing air compressor problems such as pressure loss or the compressor not building pressure. Here's a step-by-step guide to changing the oil, based on my routine:

  1. Preparation:
    • Gather necessary tools: Allen wrench, disposable gloves, container for old oil, funnel, and towels for spills [18][20].
    • Ensure the compressor is turned off and cooled down.
  2. Draining Old Oil:
    • Remove the oil fill plug to aid airflow during draining [21].
    • Use a quarter-inch ratchet with a ten-millimeter socket to remove the bolt and drain the old oil into the container [18][21].
    • Clean the sight glass with engine degreaser and dry it before proceeding [19].
  3. Refilling New Oil:
    • Refill with 15 to 16 ounces of 30-weight non-detergent oil or suitable synthetic oil for air compressors, ensuring the oil level is just above the red dot on the sight glass [18][19].
    • Replace the air filter to ensure optimal air quality [19].
    • Check the oil level by turning on the compressor, adjusting as necessary to align with the sight glass indication [21].
    • Wipe off any excess oil from the seal to prevent leaks [19].

Proper disposal of the old oil at a household waste disposal center is crucial for environmental responsibility [20]. Following these steps every 100 to 200 hours of operation—or as specified by Jinjing—ensures the compressor runs smoothly and efficiently [18].

Cleaning and Replacing Air Filters

Maintaining the air filters on my Jinjing 120HP diesel air compressor is a critical step in ensuring it operates efficiently and avoids the common issue of not building pressure. Here's how I manage this vital component:

  • Location and Cleaning:
    • The engine and compressor side filters are positioned side by side within the engine compartment, making them easily accessible for maintenance [7].
    • To clean, I gently tap the filter element against a hard surface. This action helps shed loose debris from the fibers, ensuring that airflow is not obstructed [7].
    • After cleaning, if the filter appears damaged or beyond its service life, I proceed to replace it with a new element, unwrapping and placing it securely in the filter housing [7].
  • Filter Replacement:
    • For models equipped with a canister-style filter, which features a twist-lock style base, I ensure to match the replacement filter's size based on the outside diameter, considering that smaller filters correspond to compressors with lower CFM and output [24].
    • Replacing the air filter involves unscrewing the cap, visually inspecting the filter for any damage, and if necessary, installing a new, clean filter. I make sure to tighten the cap hand tight to avoid any air leaks [25].
  • Preventative Measures:
    • Regular cleaning of the inlet air filters is essential to prevent dust and debris from entering the compressor, which can lead to efficiency losses and potential damage [13].
    • It's crucial to replace air and oil filters as needed to maintain optimal performance and prevent issues such as air compressor intake obstruction due to a faulty inlet valve or neglected air intake filters [14][26].

Monitoring and Maintaining Pressure Valves

In my maintenance routine for the Jinjing 120HP diesel air compressor, ensuring the proper functioning of pressure relief valves (PRVs) is a critical safety measure. Here's how I approach this:

  • Understanding PRVs: PRVs are designed to protect the air compressor from excessive pressure by releasing excess pressure when it exceeds the maximum working pressure (MWP). They are typically set above the high-pressure safety switch and at or below the vessel's MWP to prevent damage and ensure safety[9].
  • Routine Inspections:
    1. Quarterly Check: Every three months, I inspect the check valves to ensure they are functioning correctly. This helps in identifying any faulty pressure release valves that might compromise the system's integrity[15].
    2. PRV Malfunction Signs: If the PRV fails open, it results in continuous air venting, leading to production loss and potential safety hazards. Conversely, if the PRV fails closed, it may cause excessive pressure buildup, risking storage tank rupture and injury. Therefore, any sign of PRV opening necessitates an immediate inspection by a local air compressor distributor, possibly requiring valve replacement for safe operation[9].
  • Safety Compliance: It's paramount that the rated pressure of the PRV does not exceed the maximum allowable working pressure (MAWP) marked on the air pressure vessel. This ensures the system operates within safe pressure limits, preventing any risk of over-pressurization[2].

Addressing Common Problems

Addressing common issues with the Jinjing 120HP air compressor can often feel daunting, but with the right approach, many problems can be resolved quickly. Here's how I tackle some of the most frequent challenges:

  • Power and Starting Issues:
    • Ensure the power cable is plugged directly into a mains supply, avoiding extension cables or power strips [28].
    • Check for a disconnected power cord, deactivated power switch, or lack of sufficient air pressure in relation to the cut-in pressure [27].
    • Inspect the battery, battery isolation switch, and safety switches for a completely dead compressor; for one that doesn't crank, scrutinize electrical connections and safety switches [1].
  • Pressure and Air Flow Problems:
    • For compressors that won't load or build pressure, examine the loading/inlet valve and control system [1].
    • Regularly clean or replace the air filter and oil/water separators to prevent blockages that can lead to pressure issues [15][28].
    • Address leaks by tightening couplers or replacing gaskets, piston seals, or tank check valves [22].
  • Maintenance Tips:
    • Perform preventive maintenance activities during slower periods, like winter, to prepare for busier seasons [14].
    • Change out oil/water separators every three months and inspect belts and pulleys for wear, replacing as necessary [13][15].
    • Regularly draining the tank of accumulated water prevents rusting and extends the compressor's lifespan [30].


Through a detailed exploration of Jinjing 120HP diesel air compressor maintenance, this guide has outfitted readers with the essential knowledge and techniques necessary to tackle common operational challenges effectively. From understanding the compressor’s manual, performing routine checks and maintenance, to handling specific tasks such as oil changes and air filter replacements, we’ve dissected the pivotal steps to ensure compressor longevity and optimal performance. The journey has underscored the importance of routine maintenance and the pivotal role it plays in preventing common issues such as pressure loss, ensuring the Jinjing air compressor remains a reliable asset in industrial and construction settings.

The broader implications of this guide reach beyond mere operational efficiency; they extend into safety, environmental responsibility, and the potential for significant cost savings through preventive measures. By emphasizing the significance of familiarizing oneself with the compressor's components, adhering to a disciplined maintenance schedule, and addressing problems with informed solutions, this guide aims to empower users with the confidence to manage their Jinjing 120HP diesel air compressor effectively. For those seeking to ensure their equipment’s peak performance and reliability, the insights offered here serve as an essential resource, encouraging further research and action in compressor maintenance practices.


Q: What could be preventing my air compressor from reaching adequate pressure?
A: A faulty reed valve is often the culprit when a reciprocating air compressor fails to build sufficient pressure. In single-stage models, this can cause air to leak out of the air inlet, while in two-stage piston compressors, it might result in air escaping through the intercooler safety valve.

Q: My air conditioning compressor operates but doesn't generate pressure. Why?
A: If your AC compressor is running but not building pressure, it is likely due to valve failures within the unit. Consequently, the compressor continues to run without effectively compressing the refrigerant, which also leads to lower electrical current usage.

Q: How can I resolve the issue of low pressure in my air compressor?
A: To fix a low-pressure problem in an air compressor, start by inspecting the inlet and drain valves for any leaks. Additionally, check the safety valve to ensure it is not the source of the leak.

Q: What are the typical reasons for air compressor breakdowns?
A: Air compressors can fail due to a variety of factors, including normal wear and tear, the age of the unit, insufficient maintenance, power surges, and installation issues, among others.


[1] - https://www.air-compressor-guide.com/troubleshooting/portable-air-compressor-troubleshooting-faq
[2] - https://www.vmacair.com/blog/air-compressor-pressure-relief-valves-purpose-testing
[3] - https://www.quincycompressor.com/industrial-air-compressor-preventative-maintenance/
[4] - https://www.aircompressorsdirect.com/manuals/JennyCompressorManual.pdf
[5] - https://www.jjaircompressor.com/
[6] - https://www.atlascopco.com/content/dam/atlas-copco/local-countries/netherlands/documents/compressed-air-manual-8th-edition.pdf
[7] - https://www.youtube.com/watch?v=iPz1ML84o0s
[8] - https://bjbeneair.com/how-to-maintain-your-air-compressor-filters/
[9] - https://nigen.com/air-compressor-safety-relief-valves/
[10] - https://au.kaeser.com/services/blog/pressure-relief-valve-inspection.aspx
[11] - https://swiftequipment.com/tips-for-maintaining-air-compressors/
[12] - https://www.rasmech.com/industrial-air-compressor-maintenance/
[13] - https://nigen.com/air-compressor-maintenance-guide/
[14] - https://america.sullair.com/en/blog/maintenance-musts-portable-air-compressors
[15] - https://servicechannel.com/blog/air-compressor-maintenance-checklist/
[16] - https://www.youtube.com/watch?v=xK2iXVqm-e0
[17] - https://www.rolair.com/blog/air-compressor-maintenance-guide
[18] - https://www.youtube.com/watch?v=7oLHtW2psbA
[19] - https://www.youtube.com/watch?v=8weCB7fmMj0
[20] - https://www.youtube.com/watch?v=uTW8Da0uR2Q
[21] - https://www.youtube.com/watch?v=fjiZPrHo7tY
[22] - https://commercialaircompressor.ca/7-common-air-compressor-problems/
[23] - https://www.mitm.com/pdf/manuals/air-compressors/120-gallon-air-compressors.pdf
[24] - https://www.youtube.com/watch?v=4FIqG69yGqU
[25] - https://www.youtube.com/watch?v=7rjIuAUlag0
[26] - https://fluidairedynamics.com/blogs/articles/troubleshooting-an-industrial-air-compressor-air-compressor-problems-and-solutions
[27] - https://compressorservices.net/5-most-common-problems-air-compressors-how-fix-them/
[28] - https://www.rowse.co.uk/blog/post/how-to-troubleshoot-an-air-compressor
[29] - https://dieselengineparts.highwayandheavyparts.com/blog/diesel-brake-air-compressor-troubleshooting-4-most-common-failures
[30] - https://www.youtube.com/watch?v=obtGJywpgDo
[31] - https://www.youtube.com/watch?v=PimsozpnuC4