A/C System Hose Inspection and Replacement Gene Dianetti Parker - - PowerPoint PPT Presentation

A/C System Hose Inspection and Replacement

Gene Dianetti Parker Hannifin Corporation

A/C hose and tube assembly replacement / repair may be an

• pportunity to solve original design / installation issues. This

presentation will illustrate some of these issues Best practice or design guidelines will hopefully assist in root causing and permanently solving these issues System performance and component life may significantly be increased by making improvements to original installation!

A/C System Hose Inspection and Replacement

• Routing Issues
• Parts returned for analysis
• Hose Rub through
• Too Close to Heat Sources
• Hose Kinking
• Tube Rub Through
• Sleeves / clamps / clips to prevent abrasion / excessive heat failures
• Hose Bend Radius
• Hose Crimping
• Design Standards
• System Efficiency
• Pressure Drop Concerns
• Oil return / trapping
• Insulation
• Summary

Table of Contents

Contact between the hoses There should be no contact

Hose Rub Through

Retractable Cab Applications, i.e. Skid Steer

Retractable driver seat access For engine area for service Must be careful to keep A/C line From pinching, rubbing or laying On any hot surfaces

Hose Rub Through

Too Close to Heat Source

A/C Line Rubbing

Tube Rub Through

Sleeves Prevent Abrasion / Heat Issues

Sleeves to prevent damage from abrasion contact Heat Sleeve

Clamps / Straps Secure Hoses / Tubes to Prevent Contact

Dual Tie Strap P- Clamp Hose/ Tube Clamp

Hose Kink Due to Routing

Issue: hoses leaning against turbo. Issue: A/C line kinked

Excessive Bending at Hose Crimp Nipple

HOSE CORE TUBE IS CUT

Too Much Twist causing Hose Collapse / Pressure Drop

Understand Hose Spec’s on Bend Radius

Excessive crimping causes nipple collapse and potential refrigerant leak No Worm gear clamps! Good hose couplings have specified components and crimp dies – Do not mix!

Use of correct fittings, proper crimping dies and dimensions as specified by each manufacturer. Do not use Company A components and Company B crimp!

Hose Crimping

Required Test Equipment SAE J2064/J3062

Burst Stand Tensile Tester Constant Temp Ovens Thermal Chamber Moisture Ingression Stand Refrigerant Charging and Reclaim

BEND RADII MINIMUM:

• 3/8” tube O. D. Minimum of 5/8” (3/4” Preferred)
• 1/2” tube O. D. Minimum of 3/4”
• 5/8” tube O. D. Minimum of 1”
• 3/4” tube O. D. Minimum of 1 ¼ (1 ½” Preferred)
• 1” tube O. D. Minimum of 2”

Design Guide For Tube Bend Radii

Why? Prevent tube flattening which can cause restriction / pressure drop

BEND TANGENTS:

Shell to Tangent of Bend - Minimum of 5/8” straight from any edge on the 3/8” through 5/8” tube O. D. Minimum of 3/4” straight from any edge on 3/4” tube O. D. Tangent-to-Tangent - End of one bend to start of another bend, minimum of 1” straight. Tangent-to-back of nut or block - Minimum of 5/8" straight length

Design Guide For Bend Tangents

Why? Keep from bending too close to braze/weld joints Prevent tube cracking or flattening

System Efficiency - Pressure Drop

• Pressure Drop
• Excessive low side pressure drop can decrease performance
• Cause higher than design saturated evaporator pressure / temperatures
• Causes
• Undersized suction line / hose
• Hose twist
• Hose kink
• Excessive tube bends
• Flattening of the tubes during bending

System Efficiency - Oil Return / Trapping

• Variable Compressor Systems
• Little oil leaves the compressor during operation
• Fixed Displacement (FD) Compressor Systems (Piston / Scroll)
• Rely on oil circulation with refrigerant
• Can be sensitive to oil trapping in the low side during low load (low

refrigerant velocity) situations

• Minimize potential oil “traps” with suction hose assembly routings
• High Mounted Compressors (FD) May Be Sensitive to Hose Routings
• Extended off cycle oil migration – “Oil Washing” effect
• Depends upon relative position of each component in the system

Asphalt Tape

System Efficiency - Insulation

Foam Sleeve

SUMMARY

• When servicing A/C systems, examine the layout and root cause problem. Use

proper techniques / practices when making improvements to correct the issue.

• Follow recommended design standards to avoid hose kinking, tube flattening
• r cracking which will cause system breakdown and poor performance
• A/C Hose assemblies are normally routed in tight spaces. Avoid contact points

and keep away from high heat sources. Use clamps, clips and sleeves to protect the assembly. Insulation may improve performance by isolating heat sources from the suction line

• Select qualified repair components and assembly techniques which meet the

requirements of the OEM manufacturer and industry standards (SAE).

• Continue learning and applying best practices when servicing A/C systems to

maintain high quality levels

Thank You!

Contact Information: Gene Dianetti Parker Hannifin Hose Products Division gdianetti@parker.com