02Meritor Air System Maintenance Tech Tip130012152017

MIDWESTWHEEL.COM IOWA MISSOURI DES MOINES 1436 E. Ovid Ave. office 515.265.1491 fax 515.265.4120 parts fax 800.314.4329 parts 800.888.0248 CEDAR RAPIDS 200 50th Ave. S.W. main 319.365.4453 fax 319.365.6327 parts fax 877.706.6085 parts 800.332.5435 DAVENPORT 8502 Northwest Blvd. main 563.322.2671 fax 563.322.5940 parts 800.553.1886 SIOUX CITY 1819 E. 4th St. main 712.252.7969 fax 712.252.6149 parts 800.943.3534 CLEAR LAKE 840 Hwy. 18 W. main 641.357.7101 fax 641.357.8190 parts fax 800.548.9674 parts 800.397.5630 KANSAS CITY 5801 E. Front St. main 816.471.1552 fax 816.471.0813 parts 800.821.7402 TRUCK PARTS SUPER STORE TM December 5, 2017 (02Meritor Air System Maintenance Tech Tip) Replacement Requirements Component When to Replace* Why Purge Valve No purge cycle when compressor unloads - normal pressure at dryer control port 4 (governor port). Valve is stuck in the closed position, or not functioning properly. Air flows from purge valve during compressor’s load cycle - no pressure at dryer control port. Valve is stuck in the open position, or not functioning properly. Pressure Protection Valve Pressure protection valves will not open (air dryer must be replaced). Valves are stuck in closed position. Turbo Cut-Off Valve Air compressor stuck pumping, TCU remains open. System will build pressure until safety valve opens in system. Signal lines loss. Air flows from purge valve during compressor unload cycle after purge cycle, and flow is noticeably stronger at high engine RPM, especially under load. Turbo cut-off valve leaking. No pressure build-up in system - high compressor discharge line pressure. Valve stuck in closed position. Regeneration Valve Regeneration cycle continues after compressor begins, and secondary tank pressure drops 15 psi (103 kPa) or more. Regeneration valve allowing too much air to come back into cartridge. Purge cycle is too short (five seconds or less) - pressure-controlled check valve is OK, no leak in governor control line. Regeneration valve not allowing enough air to come back into cartridge. Air dryer purges - but no regeneration, no check valve between air dryer and supply tank, and purge valve has not closed. Regeneration valve not allowing any air to come back into cartridge. Pressure-Control Check Valve Regeneration cycle too short; may result in water in tank. Valve checks (stops airflow) too high. * Service intervals indicated are Meritor WABCO product, please consult your supplier for specific service recommendations.