BENDIX BW2077 Manuale Utente

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, and reduces the effectiveness of the device to 
dry air. Use of these or other substances can damage the 
air dryer and will void the warranty.

1. Check all lines and fi ttings leading to and from the air 

dryer for leakage and integrity. Repair any leaks found.

2. Build up system pressure to governor cut-out and note 

that the AD-IS

®

 air dryer purges with an audible escape  

of air. Watch the system pressure for leakage for a ten 
minute period. If pressure drop exceeds, for a single 
vehicle - 1 psi/minute from either service reservoir; or for 
tractor trailer - 3 psi/minute from either service reservoir, 
inspect the vehicle air systems for sources of leakage 
and repair them. 

3. Caution: Be sure to wear safety glasses in case of a 

purge blast. Check for excessive leakage around the 
purge valve of the dryer, not in the purge cycle, with 
the compressor in the loaded mode (compressing air). 
Apply a soap solution to the purge valve exhaust port and 
observe that leakage does not exceed a 1” bubble in 1 
second. If the leakage exceeds the maximum specifi ed, 
refer to section entitled Troubleshooting, Symptom 4.

4. Build up system pressure to governor cut-out and note 

that one of the AD-IS

®

 EverFlow

™

 assembly dryers 

purges with an audible burst of air, followed immediately 
by approximately 30 seconds of air fl owing out of the 
purge valve. “Fan” 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 
the AD-IS

®

 EverFlow

™

 assembly other air dryer purge. 

If system does not follow this pattern, refer to section 
entitled Troubleshooting, Symptoms 1, 2 and 3.  Check 
the operation of the end cover heater and thermostat 
assembly during cold weather operation as follows:

A. Electric Power to the Dryer  NOTE:  The EverFlow

™

 

assembly should be wired through the ignition and not 
the battery.  With the ignition or engine kill switch in 
the RUN 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 connections of the 
female connector on the vehicle power lead. 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.  The EverFlow

™

 assembly 

requires the correct electrical voltage to operate 
properly.

B. Thermostat and Heater Operation (Refer to Figure 

3).  NOTE: These tests can only be conducted during 
cold weather operation. Turn off the ignition switch 
and cool the thermostat and heater assembly to below 
40 degrees Fahrenheit. 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 approximately 90 
degrees Fahrenheit 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.

HEATER & THERMOSTAT 

CONNECTOR