Tech Tip: Knocking Noise Coming From Isuzu's A/C System

Tech Tip: Knocking Noise Coming From Isuzu’s A/C System

A knocking noise coming from the A/C system of a 1992 Rodeo (UC) model (produced before 12/16/91, equipped with factory- or port-installed air conditioning), when the A/C is running may indicate that the A/C system is overcharged.

A knocking noise coming from the A/C system of a 1992 Rodeo (UC) model (produced before 12/16/91, equipped with factory- or port-installed air conditioning), when the A/C is running may indicate that the A/C system is overcharged. Follow the test below to determine a possible A/C overcharge condition.

Service Procedure:
1. Start the engine and set the A/C system as follows:
• A/C switch depressed (on);
• Blower fan lever to medium-high (#3) position;
• Mode lever to “vent” position; and
• Air intake lever to “recirc” position.
2. Open the vehicle doors.
3. Warm the engine to normal operating temperature and allow it to idle for five minutes.
4. Check the sight glass on the receiver/drier for a clear condition.
5. Disconnect the A/C compressor clutch lead wire.
6. Monitor the sightglass for a liquid level drop. The drop will appear as bubbles in the sightglass. Record the amount of time from compressor shutoff until the first sign of bubbles in the sightglass. This is the “drop time.”
7. Repeat the above test three more times, allowing the A/C system to run for about 30 seconds between each test.
8. If the average drop time of the four tests is above 50 seconds, or if drop times in all four tests are above 30 seconds, the A/C system is overcharged.If this is the case, the refrigerant should be recovered and the correct amount of refrigerant (2.2 lbs.) charged to the system.
9. Reconnect the A/C compressor clutch lead wire.

Courtesy of Mitchell 1.

For additional information, visit www.mitchell1.com.

You May Also Like

Wrenchers Doubles Repair Tool & Equipment Offering

More than 25,000 lifts, tools, and equipment from 39 brands available online or by phone.

Wrenchers has more than doubled the vehicle repair tools and shop equipment available in its new catalog, offering over 25,000 car lifts, specialty tools, tire changers, shop fans, and more from 39 brands. 

“We are committed to continuously improving our product lineup to make Wrenchers a one-stop-shop for tools and garage equipment,” says Karla Zarate, director of sales operations. “When we launched Wrenchers as an improved version of long-time distributor Garage Equipment Supply in 2022, we had about 12,000 product numbers in our catalog. We’re at more than 25,000 now, with more in the pipeline. This means our customers can get more of what they need with just a click, rather than having to waste time shopping around.”

Myers Tire Supply Introduces MTS Xpresstm

The innovative solution to consolidate purchases and control inventory costs.

Experiencing What the Tool Industry Has to Offer

ETI held its annual ToolTech conference April 17-19 at the Hyatt Regency Tamaya Resort in Santa Ana Pueblo, New Mexico.

Sandia Mountains
LIQUI MOLY Develops Liquid Thermal Manager for EV Batteries

The automotive chemical specialist is expanding its range for all-electric vehicles with Battery Coolant EV 200.

May 2023 Vehicle Care RockStar: Johnny Weber

Johnny Weber exudes confidence in his abilities to lead the band through proficiency over pageantry.

Other Posts

Variable Valve Timing Systems

Variable valve timing systems allow today’s engines to maximize performance and drivability.

Continental Tire Upgrades Test Tracks for EVs

Continental expanded its EV charging infrastructure at three company-owned test sites in Sweden, Germany and the U.S.

Streamlight Names E.A. Langenfeld & Associates 2022 Automotive Sales Rep Agency of the Year

The company received the award yet again in recognition for outstanding national sales achievement.

MAHLE and Midtronics Join Forces for Battery Service 

The goal of the cooperation: holistic battery diagnostics and maintenance from a single source in a growing future market.