I have a ruud ac/heat unit with em.heat mod.# uhqa-1015tks and therm. mod.# lr/620 and # t874r1434n. putting in a new thermo. i discoverd that there was no power to the thermo. All breakers are on.there is power to the air handler and the outdoor unit.how can i get power to the thermo?
Your R terminal in your air-handler is the 24v power that goes to the tstat. Look at the air-handler and match the color wire. ALL tstats have a power wire going to them. If you aren't getting power, you probably have a break somewhere in the wiring close to the thermostat you are replacing.
Yes, if you don't have power at all and nothing will come on, there is typically a fuse on the control board. It should be a 5 amp fuse. If you shorted the power wire at any time when replacing the tstat, it will blow this fuse. When you replace your tstat, make sure you have the power to the unit off at the breaker box or utilize the breakers on they system its self. Some units do not have breakers on the unit its self. Hope this helps.
Ok, check that you haven't blown the transformer. If you do have 24v leaving the transformer, then you have a broken wire somewhere. If you don't have 24v leaving and and you have 240 entering the transformer, then it's gone bad. These are the only things left.
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Are there any small fuses that could have tripped?
I opened unit,but could not find any fuses.
there is no control board
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