5 ton 13 seer ruud won't defrost


Old 01-30-14, 09:44 AM
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5 ton 13 seer ruud won't defrost

Hi, so there is this AC unit that I am servicing, it won't go into defrost mode. I changed the defrost board and the temp sensors, the problem still persists. I checked the freon levels and the reverse valve, they seem to be ok. Also shorting the test pins does kick it into defrost mode.

Any suggestions on what else could be the problem?
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Old 01-30-14, 04:04 PM
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Did you get an ohm reading across the defrost stat?
Is the defrost stat secured to the outdoor coil?
Did you try jumping the defrost stat terminals?

A dirty outdoor coil or low charge can also cause ice at the outdoor unit.

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