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Anonymous Poster #1

Blocked Capillary

03/06/2013 3:01 PM

How to when an A/C capillary is clocked or blocked

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#1

Re: Blocked Capillary

03/06/2013 4:16 PM

There's no simple answer. If it's totally blocked, then the compressor will run, and do no work, so the condenser discharge line will be at room ambient (assuming steady state, where compressor has been running a long time), and as there is no refrigeration flowing through the system the evaporator and suction line will be at room ambient. The compressor housing may be hot/warm as the motor has operating losses, and will conduct the heat from motor/compressor to the housing.

If partially blocked, it depends on how much, and how long it's been running in this state, as you could have a partially frosted evaporator closest to where the capillary is connected. This assumes that there is no large heat load or insulation losses that keeps provide more heat to the evaporator then the partially plugged capillary allows of refrigerant flow and heat removal. This is similar to a slightly undercharged capillary system, where the relative pressures on both the condensing and evaporator sides are reduced, allowing a portion of the evaporator to operate below it's normal temperature relative to the saturated pressure enthalpy curves for the refrigerant working fluid.

I hope I worded this in an intelligible fashion.

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#4
In reply to #1

Re: Blocked Capillary

03/09/2013 11:31 AM

Thank u sir

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#2

Re: Blocked Capillary

03/06/2013 4:18 PM
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#3

Re: Blocked Capillary

03/06/2013 5:37 PM

This can be one of the most difficult problems to diagnose, fortunately it's rare in a/c systems.....Usually do to some condition that starves the return to the compressor and results in the oil being pumped out and basically oil logging the cap tubes....There can also be a piece of trash in the system, such as a small chunk of solder that has dripped into the system from a joint being over soldered, this is usually easier to spot as it results in the icing of the cap tube, when the system has a full charge....Also if it's a system using a mineral based lubricant, overheating or moisture contamination can result in the accumulation of a waxy buildup....I found one once that was the result of a previous repair that had blocked the cap tube completely with solder....The first question I would ask is why do you suspect a capillary tube blockage...? In any case I would try a few things such as pumping the system down, heating the cap tubes up with a hot air gun, changing the refrigerant and filter driers....

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#5

Re: Blocked Capillary

03/09/2013 3:31 PM

How many capillaries are feeding the evaporator?

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