My slightly out-of-warranty (by 1 month) CH twin tank compressor won't
switch on any more. I've hardly used the thing.

It has a LEFOO LF10-4H pressure switch which I suspect is the problem.
I need to borrow a meter to check voltages at the contacts as a first step.

That said, is there some part that could have jammed that I could free
somehow? There is a brass spring plunger on the side of the thing with
a Torx adjustment screw (it touches the same plate that moves the
contacts) whose function I don't really understand. I imagine there is
also an assembly under the module that "pops up" to break the contacts
when cut-out pressure is reached. This can be adjusted by two screws -
one for both cut-in/cut-out pressure and one for cut-in only. I haven't
changed these settings.

The damn switch costs more than half what I paid for the compressor!

Any info on what adjustments/checks I can do myself would be
appreciated, especially a description of how the thing
operates...including the plunger on the side.

I will also contact CH to see if they can do a warranty repair.

I'm not very impressed.

The three adjustments are :
Auto / OFF switch which should be set to Auto
Setpoint which sets the Cut IN value
Range which sets the differential and Cut out value
Factory set Cut in 50psi Diff 30psi Cut out 80 psi

"Pat Coghlan" wrote in message
...
My slightly out-of-warranty (by 1 month) CH twin tank compressor won't
switch on any more. I've hardly used the thing.

It has a LEFOO LF10-4H pressure switch which I suspect is the problem. I
need to borrow a meter to check voltages at the contacts as a first step.

That said, is there some part that could have jammed that I could free
somehow? There is a brass spring plunger on the side of the thing with a
Torx adjustment screw (it touches the same plate that moves the contacts)
whose function I don't really understand. I imagine there is also an
assembly under the module that "pops up" to break the contacts when
cut-out pressure is reached. This can be adjusted by two screws - one for
both cut-in/cut-out pressure and one for cut-in only. I haven't changed
these settings.

The damn switch costs more than half what I paid for the compressor!

Any info on what adjustments/checks I can do myself would be appreciated,
especially a description of how the thing operates...including the plunger
on the side.
I will also contact CH to see if they can do a warranty repair.

I'm not very impressed.

It turns out there's a breaker/reset on the motor (mounted beside one of
the capacitors) which must have popped. My 7 year-old twin looked it
over and found it (well, I helped by turning it on its back in our
living room). There's no reference to it in the manual.

BTW, there's some kind of spring plunger on the side of the pressure
switch housing. I can't figure out what it does. If anything, it would
push *down* on the plate that rises to open the contacts (i.e. prevent
it from rising...but I don't see why anything would want to prevent
contacts from opening).

Telstra wrote:
The three adjustments are :
Auto / OFF switch which should be set to Auto
Setpoint which sets the Cut IN value
Range which sets the differential and Cut out value
Factory set Cut in 50psi Diff 30psi Cut out 80 psi

"Pat Coghlan" wrote in message
...
My slightly out-of-warranty (by 1 month) CH twin tank compressor
won't switch on any more. I've hardly used the thing.

It has a LEFOO LF10-4H pressure switch which I suspect is the
problem. I need to borrow a meter to check voltages at the contacts
as a first step.

That said, is there some part that could have jammed that I could
free somehow? There is a brass spring plunger on the side of the
thing with a Torx adjustment screw (it touches the same plate that
moves the contacts) whose function I don't really understand. I
imagine there is also an assembly under the module that "pops up" to
break the contacts when cut-out pressure is reached. This can be
adjusted by two screws - one for both cut-in/cut-out pressure and one
for cut-in only. I haven't changed these settings.

The damn switch costs more than half what I paid for the compressor!

Any info on what adjustments/checks I can do myself would be
appreciated, especially a description of how the thing
operates...including the plunger on the side.
I will also contact CH to see if they can do a warranty repair.

I'm not very impressed.

"Pat Coghlan" wrote in message
...
It turns out there's a breaker/reset on the motor (mounted beside one of
the capacitors) which must have popped. My 7 year-old twin looked it over
and found it (well, I helped by turning it on its back in our living
room). There's no reference to it in the manual.

BTW, there's some kind of spring plunger on the side of the pressure
switch housing. I can't figure out what it does. If anything, it would
push *down* on the plate that rises to open the contacts (i.e. prevent it
from rising...but I don't see why anything would want to prevent contacts
from opening).

Telstra wrote:
The three adjustments are :
Auto / OFF switch which should be set to Auto
Setpoint which sets the Cut IN value
Range which sets the differential and Cut out value
Factory set Cut in 50psi Diff 30psi Cut out 80 psi

"Pat Coghlan" wrote in message
...
My slightly out-of-warranty (by 1 month) CH twin tank compressor won't
switch on any more. I've hardly used the thing.

It has a LEFOO LF10-4H pressure switch which I suspect is the problem.
I need to borrow a meter to check voltages at the contacts as a first
step.

That said, is there some part that could have jammed that I could free
somehow? There is a brass spring plunger on the side of the thing with
a Torx adjustment screw (it touches the same plate that moves the
contacts) whose function I don't really understand. I imagine there is
also an assembly under the module that "pops up" to break the contacts
when cut-out pressure is reached. This can be adjusted by two screws -
one for both cut-in/cut-out pressure and one for cut-in only. I haven't
changed these settings.

The damn switch costs more than half what I paid for the compressor!

Any info on what adjustments/checks I can do myself would be
appreciated, especially a description of how the thing
operates...including the plunger on the side.
I will also contact CH to see if they can do a warranty repair.

I'm not very impressed.

It may be an unloader valve which opens when the contacts open so that the
pressure in the compressor is released. This keeps the compressor from
trying to start with pressure in the cylinder(s).

Don Young

Don Young wrote:
"Pat Coghlan" wrote in message
...

It turns out there's a breaker/reset on the motor (mounted beside one of
the capacitors) which must have popped. My 7 year-old twin looked it over
and found it (well, I helped by turning it on its back in our living
room). There's no reference to it in the manual.

BTW, there's some kind of spring plunger on the side of the pressure
switch housing. I can't figure out what it does. If anything, it would
push *down* on the plate that rises to open the contacts (i.e. prevent it
from rising...but I don't see why anything would want to prevent contacts
from opening).


It may be an unloader valve which opens when the contacts open so that the
pressure in the compressor is released. This keeps the compressor from
trying to start with pressure in the cylinder(s).
It's similar to http://web.ncf.ca/ff293/Public/Switch.png (see red arrow)

When the little tab - which is part of the plate that moves the contacts
- below the brass cylinder (connected to tank pressure) rises, the
contacts open. The needle in the cylinder just sits there, with the tab
rising to meet it. If the needle were to get pushed down (from air
pressure), this would force the contacts to close and activate the
motor. Why would the designer want the motor to operate when pressure
rises?

"Pat Coghlan" wrote in message
...
Don Young wrote:
"Pat Coghlan" wrote in message
...

It turns out there's a breaker/reset on the motor (mounted beside one of
the capacitors) which must have popped. My 7 year-old twin looked it
over and found it (well, I helped by turning it on its back in our
living room). There's no reference to it in the manual.

BTW, there's some kind of spring plunger on the side of the pressure
switch housing. I can't figure out what it does. If anything, it would
push *down* on the plate that rises to open the contacts (i.e. prevent
it from rising...but I don't see why anything would want to prevent
contacts from opening).


It may be an unloader valve which opens when the contacts open so that
the pressure in the compressor is released. This keeps the compressor
from trying to start with pressure in the cylinder(s).
It's similar to http://web.ncf.ca/ff293/Public/Switch.png (see red arrow)

When the little tab - which is part of the plate that moves the contacts -
below the brass cylinder (connected to tank pressure) rises, the contacts
open. The needle in the cylinder just sits there, with the tab rising to
meet it. If the needle were to get pushed down (from air pressure), this
would force the contacts to close and activate the motor. Why would the
designer want the motor to operate when pressure rises?
He wouldn't. The needle doesn't push the tab down, the tab pushes the needle
up when the contacts open to stop the compressor. This releases the pressure
in the compressor while a check valve holds pressure in the tank. When the
tank pressure drops, a diaphragm in the switch closes the contacts to start
the compressor. At the same time the needle is released so that the
compressor air is no longer vented and can build up pressure to open the
check valve and repressurize the tank.

Don Young

Don Young wrote:
"Pat Coghlan" wrote in message

When the little tab - which is part of the plate that moves the contacts -
below the brass cylinder (connected to tank pressure) rises, the contacts
open. The needle in the cylinder just sits there, with the tab rising to
meet it. If the needle were to get pushed down (from air pressure), this
would force the contacts to close and activate the motor. Why would the
designer want the motor to operate when pressure rises?
He wouldn't. The needle doesn't push the tab down, the tab pushes the needle
up when the contacts open to stop the compressor. This releases the pressure
in the compressor while a check valve holds pressure in the tank. When the
tank pressure drops, a diaphragm in the switch closes the contacts to start
the compressor. At the same time the needle is released so that the
compressor air is no longer vented and can build up pressure to open the
check valve and repressurize the tank.

Ah, okay, that makes sense. I figured there must be something under the
switch (diaphragm) moving the plate, but started to think that maybe the
needle might be moving the contact plate, rather than as you described.

Does the diaphragm suddenly "pop up", opening the contacts and releasing
pressure from the compressor? It would be hard to make the two happen
gradually.

In article ,
Patrick Coghlan wrote:

Don Young wrote:
"Pat Coghlan" wrote in message

When the little tab - which is part of the plate that moves the contacts -
below the brass cylinder (connected to tank pressure) rises, the contacts
open. The needle in the cylinder just sits there, with the tab rising to
meet it. If the needle were to get pushed down (from air pressure), this
would force the contacts to close and activate the motor. Why would the
designer want the motor to operate when pressure rises?
He wouldn't. The needle doesn't push the tab down, the tab pushes the
needle
up when the contacts open to stop the compressor. This releases the
pressure
in the compressor while a check valve holds pressure in the tank. When the
tank pressure drops, a diaphragm in the switch closes the contacts to start
the compressor. At the same time the needle is released so that the
compressor air is no longer vented and can build up pressure to open the
check valve and repressurize the tank.

Ah, okay, that makes sense. I figured there must be something under the
switch (diaphragm) moving the plate, but started to think that maybe the
needle might be moving the contact plate, rather than as you described.

Does the diaphragm suddenly "pop up", opening the contacts and releasing
pressure from the compressor? It would be hard to make the two happen
gradually.

Listen to the compressor when it shuts off. The hiss you hear after the
motor stops is the result of the unloader valve opening to release
pressure in the compressor. It opens more or less instantly but takes a
second or two to bleed off pressure.

Smitty Two wrote:
In article ,
Patrick Coghlan wrote:

Don Young wrote:
"Pat Coghlan" wrote in message
When the little tab - which is part of the plate that moves the contacts -
below the brass cylinder (connected to tank pressure) rises, the contacts
open. The needle in the cylinder just sits there, with the tab rising to
meet it. If the needle were to get pushed down (from air pressure), this
would force the contacts to close and activate the motor. Why would the
designer want the motor to operate when pressure rises?
He wouldn't. The needle doesn't push the tab down, the tab pushes the
needle
up when the contacts open to stop the compressor. This releases the
pressure
in the compressor while a check valve holds pressure in the tank. When the
tank pressure drops, a diaphragm in the switch closes the contacts to start
the compressor. At the same time the needle is released so that the
compressor air is no longer vented and can build up pressure to open the
check valve and repressurize the tank.
Ah, okay, that makes sense. I figured there must be something under the
switch (diaphragm) moving the plate, but started to think that maybe the
needle might be moving the contact plate, rather than as you described.

Does the diaphragm suddenly "pop up", opening the contacts and releasing
pressure from the compressor? It would be hard to make the two happen
gradually.

Listen to the compressor when it shuts off. The hiss you hear after the
motor stops is the result of the unloader valve opening to release
pressure in the compressor. It opens more or less instantly but takes a
second or two to bleed off pressure.

I'm developing a greater sense of appreciation for the number of parts
on this little $99 beast.

I think I do recall the thing hissing when the motor cuts out. I guess
the chain of events is: a) at cut-off, the diaphragm in the pressure
switch punches up to open the contacts and activate the unloader and b)
check valve closes once pressure is released.