ISO 5898:1997

Overview

ISO 5898:1997 - Passenger cars - Rear-window defrosting system - Test method - defines a laboratory test procedure for assessing rear-window defrosting systems on passenger cars. Published by ISO (second edition, 1997), the standard specifies definitions, test equipment, environmental and vehicle preparation, test conditions and a photographic method for recording the defrosted area. ISO 5898 does not set pass/fail performance levels or reference areas; it provides a repeatable method for measuring defrosting performance.

Key topics and requirements

• Scope and definitions

  • Applies to passenger cars (as defined in ISO 3833) and to systems intended by the manufacturer to eliminate frost/ice from the rear-window.
  • Defines terms such as defrosted area, rear-window defrosting system, and road load.

• Test equipment

  • Environmental chamber sized to contain the complete vehicle and able to maintain either -18 °C – 3 °C (full range) or -8 °C – 2 °C (restricted range).
  • Specified spray-gun characteristics (nozzle diameter 1.7 mm, nominal flow 395 ml/min, projection cone diameter 300 mm at 200 mm from nozzle - operating pressure given as shown in the standard).

• Preparation and conditioning

  • Thorough degreasing of inner and outer glazed surfaces (methylated spirit or equivalent), ammonia solution (3–10 %) application and drying, then wiping.
  • Vehicle stabilized at test temperature for not less than 10 hours (can be shortened with instrumentation verifying stabilized coolant/lubricant/air temperatures).

• Test method

  • Form an even frost coating (specified mass per area as given in the standard) using the spray-gun; allow 30–40 minutes after frosting before test start.
  • Start engine and operate defrosting controls as recommended by manufacturer. Engine running conditions are defined (optional 5 min warm-up; then specified engine speed or chassis dynamometer simulating road load).
  • Electrical supply: battery fully charged; defrost device terminal voltage shall not exceed 20% above nominal.

• Measurement and recording

  • Record defrosting pattern at intervals using the recommended photographic method (Annex A) or tracing technique; photographic geometry and lighting guidance provided (camera optical axis located relative to inside rear-view mirror; image major-axis dimension ≥ 200 mm).

Applications and users

• Who uses ISO 5898:

  • Automotive manufacturers and component suppliers - for design validation and comparative testing of rear-window heaters and integrated defrost/wipe systems.
  • Vehicle test laboratories and type-approval bodies - to perform repeatable laboratory assessments supporting regulatory or customer requirements.
  • R&D teams - to evaluate design changes, materials or control strategies affecting defrost performance.

• Practical value:

  • Provides a standardized, reproducible method to quantify cleared (defrosted) area and to compare system performance under controlled cold conditions.
  • Supports product development, quality assurance, homologation testing and benchmarking between designs.

Related standards

• ISO 5897 - Rear-window demisting system - Test method (related in the same series)
• ISO 6255:1997 - Rear-window washing and wiping systems - Test methods
• ISO 3468 / 3469 / 3470 / 9619 - Windscreen defrosting/demisting/washing/wiping test methods
• ISO 3833, ISO 1176 - referenced for vehicle definitions and mass codes

Keywords: ISO 5898, rear-window defrosting, test method, passenger cars, defrosting system, environmental chamber, spray-gun, defrosted area, automotive testing.