Hughes Blog
Thoughts on Software Development, Project Management, Parenting, and Running.
Saturday, July 23, 2005
HVAC Repairs
Thursday Fran called to report the one of our AC units had cut out. July in North Texas when the average high temperature is usually 100 degrees, is no time for the AC to stop working. The bungalow has two units one large unit for the main part of the house and one smaller unit that cools three of the four bedrooms - poor Marissa was the odd man out.

When I got home I reconnoitered the situation. The first clue was the water pouring out of the condensation drain. Second clue, the compressor was running, even though the thermostat control had been switched to OFF. Third clue: earlier this week I had changed the filters with a new type. I checked the filter and it had partially ripped out of its frame. As noted, the condensation pan held quite a bit of water.

My first conclusion was that unit had frozen up. This can be caused by several things. Low Freon is one common reason. If the filter paper was clogging up the airflow, that could also be one reason. So I replaced the filter. Then I shut down the system for while. Then I put the gauges on the unit and fired it up. It was working. I checked the air temperature; it was blowing near 60 degrees. That was good. So I let it run and cool off the house, while I watched Stage 18 of The Tour.

Around midnight, the house was finally cool and the thermostat shut the system off. Just to make sure, I went outside and checked the compressor. It was still running. The suction pipe was frosted over. It was starting to freeze up. I had missed the obvious clue in my analysis - clue two. If the compressor is running and the blower is not moving air over the evaporator, then the evaporator will freeze up. What causes the compressor to run after blower shuts off is a faulty relay on the compressor motor. On my system this is called a contactor.

Friday morning I removed the faulty part. Fran procured a new one for $15. It was installed Friday evening. And we are back to having a cool house. :-) Ahhh...

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All views expressed in this post and on this blog are my own. None of my comments should be construed to represent the views of others including and not limited to: BMC Software Inc., Corel Corporation, Dun and Bradstreet and AC Nielsen. Copyright Chris Hughes 2004-2012