The problem is that while the refrigerant does return, the oil doesn't do so well in an undercharged system.
http://www.airsept.com/Articles/RecycleGuard/Motor0403.pdf
Quote:
At the top of the list: A “just-low”
refrigerant charge (typically a 10% to
20% undercharge) significantly reduces
oil flow, according to Four Seasons’
Jim Johnson. He gave this example
for 88°F ambient: The a/c duct
temperature rose just 3° (from 46° to
49°F), hardly enough for a customer
complaint. Yet so much oil was
trapped in the evaporator under lowrefrigerant
conditions that oil circulation
dropped from about 10% to 25%
by weight to just 2% to 4%. That’s a
prescription for increased compressor
wear and therefore short compressor
life. Other causes of similarly low oil
flow, he said, are internal restrictions
(typically from contamination, which
increases rapidly with low refrigerant),
poor airflow through the condenser
and high coolant temperatures.
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They're writing about a level of refrigerant loss that will NOT result in customer complaints, until the compressor eventually fails.
11-03-2008, 07:13 PM
Hybrid Mode
