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What are all those pipes coming out of the compressor? Answered

Hi all,
I scavenged a compressor from an old fridge, and I have a couple of questions about it.
It's a Tecumseh AE4ZF11 hermetic seal compressor.  If you google it you can find a servicing manual, which didn't help me much but maybe you can find something useful.

I basically want to use the compressor as either a vacuum pump, or an air compressor.

Now for the questions:
1) This compressor has 5 (Yes, five) pipes coming out of it.  One is a port for topping refrigerant, but I have no idea what the others are.  They all went into the fridge.  Any idea why there would be more than just one pipe going in, and one going out?

2) The control unit has been broken off before I could salvage it.  According to the manual, the tree terminals are Common, Start and Operate.  Is there a way to make the compressor work without buying a new control unit, or building something too complicated \ expensive?


Check the instructables on the left hand side of this page. But the pipes coming out are supply and return pipes. One set for the freezer coil and the other set for the fridge.

Finally got it to work.

Weird thing is, it seems to have only one supply and one return pipes. The two other pipes don't seems to do anything.

Any ideas of what up with that?

So if I want to make a vacuum \ air pump I can just block one supply and one return pipe? Or just join both supplies together with a T joint?

Plug-er in; see if the two pairs draw the same Vacuum !

if they do then I'd join them together for more volume.

Btw any more pics of the unit?

Ill post more pictures once I clean it up a bit.

Depends on the volume they produce and how they are connected inside.
If you fit a small plastic pipe over them you should be able to feel if there are major differences in airflow.

But be aware that without the oil the compressor won't run fine for long, so giving it an oily run every now and then can prolong the lifetime.

What about the missing control unit? Is it possible to start the compressor without it?

Yes, they are usually capacitor start motors.

Press the Start Button for no more then ten seconds.


You should be holding the red button closed when you apply power.

10 seconds later release the red start button.

If the motor is not running after 20 seconds disconnect the power ! !

Because in 35 seconds you can smoke (burn out) the motor.

Hooked everything up like the schematic shows (Capacitor connected with one terminal to Neutral and to compressor Run, other terminal, through a switch, to compressor Start).

When applying power, there's a slight hum (Hardly audible) coming from the compressor, but nothing else. Same sounds is heard whether the Start button is pressed or released.

How should I start trouble shooting?

All I can think of is to double or triple the capacitor MFD..

Will hooking several capacitors in parallel do the trick?
Do they have to be identical, or can I just mix MFDs and voltages?

parallel mfd ads up voltage needs to be more then line say 350VAC.

So you can parallel a 2.5 uF 450v cap with a 7.5 uF 350v to make an equivalent AC capacitor of 10 uF...

You might measure the start and run AC current on a working AC or fridge and compare those readings to your ancient French machine.

Without the sealed lubrication the motor (even if running) may seize in less then a few minutes !

That's why you need to scavenge the oil from the outlet and recirculate it.

Do you think that oil must be low atomic weight to be able to recirculate through cooling compressor expansion valve ?

It has some neat properties, because its sealed for life, its pretty thin stuff.

Will this Microwave oven capacitor do the trick?

And just to make sure, it has no polarity, right?


Yes but without the diode.

2100VAC clearly implies no polarity :)

BTW, all very good pictures.