Author Topic: New Tecumseh Compressor Seized  (Read 5868 times)

Offline 3450BB

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New Tecumseh Compressor Seized
« on: March 28, 2015, 07:00:59 PM »
The same appliance from this previous topic: http://www.hvactechgroup.com/hvacforum/index.php?topic=1643.0

It's been 3 weeks since I got the appliance working. This morning I get a call that the cooler isn't working. I get onsite and assess. The new compressor is going off on overload. Its seems to be seized! Video here: https://youtu.be/14I3kn9OY68
High side 50PSI and Low side 50PSI. My understanding with these sealed compressors is that they come set with oil. And when using a vacume pump oil from it will transfer into the compressor and vice versa.

Offline viking

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Re: New Tecumseh Compressor Seized
« Reply #1 on: March 28, 2015, 10:07:12 PM »
Assuming start cap and relay are OK I would agree compressor is seized. You could try a hard start kit. But even if it works it may not be a permanent fix.
Yes they do come precharged with oil.
If vacuum pump was shut off and left open to system while system was in a deep vacuum it is possible for pump oil to enter system. Under normal circumstances I don't see how oil would leave system into vacuum pump.
I have never ran into this problem.

If I recall this compressor seen a bit of abuse when new (over charged and piped backwards)

Offline 3450BB

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Re: New Tecumseh Compressor Seized
« Reply #2 on: March 28, 2015, 11:16:07 PM »
Under what conditions would a compressor seize? Low to no oil and over heat? I will contact Tecumseh this week about warranty/exchange. I'm thinking I should use a line-set cleaner to remove old oil but I'm not sure if its compatible with capillary. In the mean time I will vacuum down the low zone of the system and then try to start it. I think that could budge it, unless when the compressor initially went off on over load it wasn't unplugged and it re started until it over heated.

Offline 3450BB

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Re: New Tecumseh Compressor Seized
« Reply #3 on: March 29, 2015, 12:23:47 PM »
Looking around for information on my situation I found this modern service manual for hermetic sealed Tecumseh compressors. http://www.tecumseh.com/~/media/North-America/Files/Marketing-Brochure/North-America-Library/Tecumseh-Service-Handbook.pdf

A lock out can happen if liquid refrigerant gets into the compressor through the suction line, solution would be to add a dryer but there already is one on the discharge that I already replaced. An accumulator would be needed if the suction was over 100ft.

The other condition that would cause a lock out would be internal mechanical trouble.

Offline viking

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Re: New Tecumseh Compressor Seized
« Reply #4 on: March 29, 2015, 05:39:02 PM »
Typically a compressor will seize for one of two reasons.
First over charge of refrigerant particularly on a cap tube system will cause liquid flooding of compressor and wash oil out.
Second an under charged system will not provide sufficient cooling for compressor and cause it to over heat.
In either case it will cycle on overloads until its seizes.

A dryer WILL NOT prevent liquid slugging. An accumulator will.
A dryer does not belong in the discharge line. It belongs in the liquid line. If you have a drier in the discharge you absolutely need to remove it.

Do NOT attempt to start compressor while it is in a deep vacuum. At best you WILL burn out compressor. Possibly blow a terminal and hurt yourself or someone else.
What was the nature of the failure of the original compressor?
 

Offline 3450BB

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Re: New Tecumseh Compressor Seized
« Reply #5 on: March 29, 2015, 06:02:39 PM »
I don't have a dryer immediately at the discharge, its down stream from the condenser, it then outputs to the capillary to the evaporator. That is all correct. Could improper positioning of the service valve restrict oil? Like not being fully back seated? The cooler did operate for 3 weeks in a commercial setting. Having a restriction their could have held back oil.

Quote
Service valves on Tecumseh systems are “front seated” by turning the valve stem clockwise. This
closes the valve and opens the gauge port.
Turning the stem counter-clockwise “back seats” the valve and thus opens the system and closes
the gauge port.
If present, the valve port to the system control (high pressure cutout, low pressure control, fan
control, etc.) is always open regardless of the position of the valve stem.
If the system is to be operated with the service gauge functioning, it is necessary to “crack” the
valve from its back seated position for the gauges to perform. Before removing the gauges, close
the gauge port by returning the valves to their fully open position (back seated).

Offline viking

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Re: New Tecumseh Compressor Seized
« Reply #6 on: March 29, 2015, 07:17:29 PM »
I think if the valve was positioned to restrict oil return it would also restrict refrigerant flow to the point of causing cooling problems. Since it did cool for 3 weeks I don't think service valve position is the problem.

"solution would be to add a dryer but there already is one on the discharge"
"I don't have a dryer immediately at the discharge, its down stream from the condenser"

Outlet of condenser would be liquid line.



Offline 3450BB

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Re: New Tecumseh Compressor Seized
« Reply #7 on: March 29, 2015, 07:51:39 PM »
yes my error, I meant if I'm getting liquid refrigerant into the compressor then I'd need an accumulator,
Quote
   Install a suction accumulator to prevent liquid refrigerant from entering the compressor
-from the service manual.

I will speak with the retailer about an exchange on the compressor. I originally had to replace the original compressor when it seized after ten years of service. I did not investigate what led to it seizing, just assumed it served its term.

Offline viking

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Re: New Tecumseh Compressor Seized
« Reply #8 on: March 29, 2015, 08:21:30 PM »
If it were me while the compressor is out I would blow nitrogen through the discharge line and out the suction line then again through suction line and out discharge. Install new compressor purging nitrogen while brazing. Replace drier. Evacuate and weigh in charge. Check superheat and sub-cooling and adjust charge accordingly.
May not be a bad idea to leak check before doing anything. May be short of gas?
Also if you are suspicious of cap tube being choked I would replace it.

Offline 3450BB

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Re: New Tecumseh Compressor Seized
« Reply #9 on: March 30, 2015, 10:48:42 PM »
An update. I was able to get the compressor running for a few minutes by using a hard start capacitor in parallel with the start capacitor in addition to lowering the charge from a static 50PSI on the low to 20PSI with my vacuum pump. I jogged the compressor about eight times before the hum it made changed to a pumping sound. Unfortunately my high side pressure was 10PSI, and the immediate discharge port on the compressor was getting cold. About three minutes into operation the sound it made quickly changed  and it went off on over load, it seized. There clearly is a blockage in the compressor, enough to create an effect of an orifice and cool the discharge. I the pulled a deep vacuum and filled with nitrogen to 50PSI and attempted to jog the compressor again but no luck, the casing was warm, a day to cool off I should have better luck tomorrow. I will get a flushing agent too, I'll have to get one compatible with capillary.