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Blocked fan detection system for heat pump

  • US 5,528,908 A
  • Filed: 06/06/1995
  • Issued: 06/25/1996
  • Est. Priority Date: 12/10/1993
  • Status: Expired due to Term
First Claim
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1. An airflow obstruction detection method for detecting an airflow obstruction condition in an outdoor heat exchanger, comprising the steps of:

  • determining a temperature difference parameter indicative of temperature difference between the outdoor heat exchanger and the ambient air surrounding said heat exchanger at a first time;

    performing a defrost cycle when the temperature difference parameter exceeds a predetermined value;

    determining the temperature difference parameter at a second time after defrost cycle has completed;

    declaring an obstruction condition to exist if the temperature difference parameter determined at said second time is not smaller by a predetermined value than the temperature difference determined at said first time.

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