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-   -   Home Outside A/C Unit Won't Power Up (http://www.diychatroom.com/f17/home-outside-c-unit-wont-power-up-30601/)

ldeneale 10-24-2008 08:09 PM

Home Outside A/C Unit Won't Power Up
 
The unit has 220VAC to the relay, when I press in the relay the fan runs (but I don't know about everything else). If there is a way to know that everything is working would be good also. Any kind of trouble shooting. I did see 110vac on all terminals on the coke can looking deal (looks like a starter or something like that, has 4 or so wire terminals with wires going to relay and other things) A guy came out and told my mom that it was the computer board or something like that. So I took the one out of the outside unit whihc was pretty small board and I took the board out of the enclosure box outside of the unit and examined them. There doesn't seem to be any broken traces or any visual signs of burnt diodes or resisters or caps. I work at a radio shop and we do a lot of radio repairs down to the control boards so I figured I would take a look at both boards just for grins. Didn't find anything to put them back in. Would be nice to know what each of these boards do and where could I get replacements if needed? It seems like the tstat is not communicating with the relay that power everything? Or maybe the rel;ay is bad and that why everything turn on when I press it in (again I don't know if everything is coming on because the fan is so loud that it just seems like the whole system is running). It sounds like a normal A/C unit running but no air through vents. when I releasae relay of course everything shuts off. The tstat of course has been tried on cool and heat with on and off. There are no weird noises or anything. I couldn't get any voltage coming to the tstat. Have not tested wires coming from tstat to outside unit. Don't know which is which at each end. Wires don't look the same on tstat and outside unit. Breaker of course is not tripped because we have two 110vac wires coming in on relay. I'm no HVAC guy but I do know a little If anyone can help please give ideas.

Rookietinner 10-24-2008 10:37 PM

IT sounds like a low voltage issue. Have you checked the fuse at the indoor unit?

ldeneale 10-25-2008 08:30 PM

I just went under the house today and took out the main furnace contol board and checked the 3amp fuse and it was fine. I tried doing the test with connecting the C (Com 24V) to the test terminal and nothing happened. When I press in the button that the outter face plate presses in when It its put back on you can hear the relay or something clicking over and the red led flashed once and it sounds like a faint hum in the backgrond but when I release the button it goes away. There is no code on one flash and nothing happens on the face plate cover. It has code from 11 and up.

simpleman1962 10-29-2008 04:37 PM

Replace the coke looking thing (capacitor) This starts the compressor and lets it run. it should have marking like 45uf-5uf just replace with same or 10% plus or minus and should go back to running fine!

Simpleman


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