We were having an issue with the vacuum -0.7 bar test on our machine. It would only work sometimes and we were wondering why. So I emailed the manufacturer and got a call from the service center in California. They were very helpful and explained some things I could try to remedy the problem.
After tearing the whole machine apart, servicing it, then putting it back together and ending up with the same result I started fiddling around with the diagnostic mode. This mode which is built into the service program allows you to activate all of the separate valves in the system manually. I finally noticed that we only achieved enough pressure in the venturi (which draws the vacuum out of the test chamber, using high pressure airflow) when the compressor was running.
It turns out the air compressor we are using to feed the testing machine is not charging the tanks at as high a PSI as it used to. Because of this we were only getting one full negative pressure vacuum test before the machine would mysteriously fail the test. With this information now I can attempt to service the compressors regulator or just make sure to drain the tanks enough to bring the motor back on to provide me with a high enough pressure to run the test.
Regardless of the extra work, I learned a lot about the workings of the machine. It is well designed, built and very elegantly put together.
|The machine in question|
|The venturi which creates the vacuum for the system using 'Bernoulli's principle' is the plastic T fitting on the left labelled "S". To remove the top plate and test chamber, you must disconnect the input and bleed lines from the back plate, |
|And the manifold pressure line,|
|And the ribbon cable and grounding wire|
|Here you see the valve stack. They control vacuum pressure, air in and air out|
|A solenoid case without its electromagnet|
|Some small metal shaving on the sealing face of the solenoid, this was removed|
|The solenoid post, core and spring|
|These were all removed, wiped clean, blasted with air then reinstalled|
|The final valve assembly|