Question about Ruud UBHC Air Conditioner

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Thermostats being replaced often

One customer has had 5 new stats on 2 different systems. What should I look for? Transformer or house voltage issues or grounding issues?

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I have repaired A/C commercial and in dustrial for 40+ years. ( ot of ten times replacing one item as a t-stat 5 times pretty much proves it is not the thermostat. The VA rating on your transformer has to ne able to carry the total load of your circritry.

Yes, I have als seen cases wher a intermitent short occurs in the thermostat cable that has up to 6 different wires in it.

Also "Heat anticipators" in all t-stats (Unless they are automatically controlled) need to be set properly.

You need a AMP reading meter with a Volatage and Resdistence Meter.


I had one job wher a painter had nailed through the t-stat wire inside the wall and caused a short between the Red (Hot wire) and the ground wire ( in this case it was the blue wire) Depending on the t-stat ... There ar up to eight terminals that need to be i9dentified and then properly wired.

Heat pumps use at least 5-6.

5 t-stats failing is gettin close to $500 of repairs if not more.

Posted on Feb 09, 2008

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24%20v%20transformer.jpgpicture of a typical transformer.

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