After ruling out any and all pressure, check valve etc... problems I took
off the end of the motor and fiddles with the thing in side that switches
from start windings to the run windings. After I put it back together it
seemed to work better. In hindsight it did seem to start slow even when the
tank was empty but now it is like it used to be, almost instant start up at
any pressure. What could have been wrong. Could it have been trying to start
on the run windings? Can the capacitors get weak or do they just die?
"RoyJ" wrote in message
ink.net...
What Jim said. Either the unlaoder or the start cap. Try the unloader
first.

Jim Levie wrote:

On Sat, 27 Nov 2004 01:06:22 +0000, habbi wrote:


I have a problem with my 4 hp cambell hausfeld oiless direct drive air
compressor. When empty it will start and work fine but if there is 50 +
psi in the tank the motor tries to start and the thermal overload keeps
tripping out. I checked the check valve and it is clean and moves
freely,
also the unloader valve is clean and seems to work fine. Could the
problem
be in the motor, or its capacitors? Any other ideas? Thanks


That sounds like the compressor isn't unloaded. Either because the
unloader isn't functioning or because tank pressure is leaking back into
the compressor. You should be able to find out what's happening by
cracking the output connection right after the unit cycles off at
pressure. Evidence of high pressure release would indicate that the
unloader isn't working. Cracking the output connection after the unit
has
sits a while with the airtank above 50psi will tell you if there's leak
back.

It is also possible that there's a motor problem. Swapping out the start
capacitor would be a pretty cheap diagnostic.