BENDIX SD-08-2414 manual Rebuilding the Bendix AD-IPAIR Dryer, Operation & Leakage Tests

Notes:

1.Visually check for physical damage to the air dryer such as chaffed or broken air and electrical lines and broken or missing parts.

2.Check mounting bolts for tightness. Re-torque to 270–385 in-lbs.

3.Perform the Operation & Leakage Tests listed in this publication.

This air dryer is intended to remove moisture and other contaminants normally found in the air brake system. Do not inject alcohol, anti-freeze, or other de-icing substances into or upstream of the air dryer. Alcohol is removed by the dryer, but reduces the effectiveness of the device to dry air. Use of other substances can damage the air dryer and may void the warranty.

OPERATION & LEAKAGE TESTS

1.Install a pressure gauge in the #1 reservoir. Check all lines and fittings leading to and from the air dryer for leakage and integrity. Test the delivery port check valve assembly by building the air system to governor cut-out and observing a test air gauge installed in the #1 reservoir. Note the pressure on the air gauge after governor cut-out pressure is reached, a rapid loss of pressure could indicate a failed delivery port check valve. This can be confirmed by shutting the engine off, draining the air brake system pressure to a point below governor cut-in (typically < 95 psi). Make sure the dryer has completed the purge cycle (wait 30 seconds after governor cut-out) and determine if there is any air flow out of the air dryer purge valve. If air flow is detected at the purge valve, the air dryer delivery check valve should be serviced. Remove the test gauge before returning the vehicle to service.

2.Check for excessive leakage around the purge valve. With the compressor in loaded mode (compressing air), apply a soap solution to the purge valve exhaust port and observe that leakage does not exceed a one (1) inch bubble in one (1) second. If the leakage exceeds the maximum specified, repair the purge valve assembly.

3.Make sure all reservoir drain cocks are closed. Build up system pressure to governor cut-out and note that Bendix® AD-IP®air dryer purges with an audible escape of air. Apply and release the service brakes to reduce system air pressure to governor cut-in. Note that the system once again builds to full pressure and is followed by an AD-IP air dryer purge.

4.Check the operation of the end cover heater and thermostat assembly during cold weather operation as follows:

A.Electric Power to the Dryer

With the ignition or engine kill switch in the ON position, check for voltage to the heater and thermostat assembly using a voltmeter or test light. Unplug the electrical connector at the air dryer and place the test leads on each of the pins of the connector with the locking latch. If there is no voltage, look for a blown fuse, broken wires, or corrosion in the vehicle wiring harness. Check to see if a good ground path exists.

B.Thermostat and Heater Operation

Note: These tests are not required except in cold weather operation.

Turn off the ignition switch and cool the thermostat and heater assembly to below 35° F. Using an ohmmeter, check the resistance between the electrical pins in the air dryer connector half. The resistance should be 1.5 to 3.0 ohms for the 12 volt heater assembly and 6.0 to 9.0 ohms for the 24 volt heater assembly.

Warm the thermostat and heater assembly to over 90° F. and again check the resistance. The resistance should exceed 1000 ohms. If the resistance values obtained are within the stated limits, the thermostat and heater assembly is operating properly. If the resistance values obtained are outside the stated limits, replace the heater and thermostat assembly.

REBUILDING THE BENDIX® AD-IP®AIR DRYER

GENERAL

If, after completing the routine operation and leakage tests, it has been determined that one or more components of the air dryer requires replacement or maintenance, refer to the Bendix Quick Reference Catalog (BW1114), available on www.bendix.com, for the latest maintenance kits and service parts.

When rebuilding or replacing components of the air dryer use only genuine Bendix® service parts.

BENDIX AD-IP AIR DRYER REMOVAL

This air dryer removal process is presented in the event it becomes necessary to replace the entire air dryer.

Normal service and parts replacement does not require removal of the air dryer from the vehicle.

1.Park the vehicle on a level surface and prevent movement by means other than the brakes.

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