Question about Whirlwind FH-778 Air Conditioner

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I have a Lennox heat pump (1994 model HP19-461-7P, SN 5894\r\nF56813) I have been having issues with. About 6 weeks with the ac running, we smelt somthing from the house like the first time you run your heat in fall. After that the ac worked fine for a day or so, then it quit working. The system is fully charged but I did find a diode burned on the defrost control circuit board. I unplugged the wire from the defrost terminal to try and disable the defrost mode thinking this may be my problem. Unit worked fine for 2 or 3 weeks, then no ac again. When the ac quits working, I check the compressor, and it will be very hot. I can cool it off with a water hose and it will start cooling properly again. Only once did I have to reset the switch to get the compressor to restart. I am ordering a new defrost control board but not sure this will fix my problem. Also I can turn off the breakers to the whole system, turn back on, and this seems to reset everything and unit starts working again. For a while. Your help would be much appreciated. Thanks.

Posted by clayton2100 on


5 Related Answers



  • 86 Answers

SOURCE: How old is my Lennox air conditioner?

not positive but looks like 5-8-02

Posted on Jul 14, 2009


  • 614 Answers

SOURCE: AMANA AC unit Blows heat in cooling mode

These valves do get stuck. They energize for cool and in the dead postion they heat. Your valve is stuck or not energized. Can you here it click or try to energize. If you dont hee the click you do not have voltage to the valve. The valve is powered thru the defrost board. So that might be your problem. If you have voltmeter. Take the two wires off the valve and turnit on cool you should get 24 volts. If you have 24 volts the valve is bad. If you do have voltage to the valve tap the valve while energized and sometimes this will loosen them up. If the board or valve is bad you will have to call a service tech. Russ There is only so much you can do.

Posted on Jul 25, 2009



  • 232 Answers

SOURCE: BTU of an old Lennox condensing unit and A coil

38,000 btu AKA 3 ton

Posted on Sep 20, 2009

Testimonial: "Thank you for your help! Chong1238"


  • 334 Answers

SOURCE: My ac unit works sporadically. Today it cooled

First check your filters to make sure they are clean and you have proper airflow.

If they are clean, then you either have low refridgerant or dirty coils.

The outside coils can easily be cleaned by disconnecting power to the unit, then using a water hose to spray off the dirt, grass, etc.

The inside coild can be very difficult to get to on some units and require a special evaporator coil cleaner. As for adding refridgerant, the Law requires one to be certified for purchasing or working with refridgerant so you may need to call a service tech for that. Expect a bill from $100 to $225 for a typical system recharge depending on how low it is and which company you call.

Posted on Oct 10, 2009


Jeremy Moore

  • 1940 Answers

SOURCE: what size capacitor do I

Your Lennox Condenser HS18-311-7P uses a 35 MFD 370 Volt Round Run Capacitor. Here it is:

I’m happy to help further over the phone at

Posted on Jun 18, 2011

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