Residential HVAC Troubleshooting

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Residential HVAC Troubleshooting

Postby Dxrocaa4 » Fri Apr 06, 2012 4:11 pm

I'm not sure how to post a question on your web page----I ' tell you what Ineed & you tell me what I need to do. I'm a recent HAVC Tech school
graduate---The problem is that after six months of training----I actually have more questions than answers regarding HVAC servicing & repair----I am
working part-time in general maintenace which require HVAC servicing------I was lucky with my first repair---the unit only needed a capacitor----But
todays problem is not so easy-----The heater (Gas) works great----but the ac does not----the out side fan not turn on when call for cool is set on
thermostat----the fan however, does turn on when I press the contactor. Some guidance would be appreciated. Thanks.
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- Residential HVAC Troubleshooting

Postby Big » Sat Apr 07, 2012 6:38 am

tech to tech Go on line you may be able to get a telephone number.
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Postby how » Sat Apr 07, 2012 12:47 pm

The duke03 advise is worth listening to.
I had a bit of an engineering background when I first started so the first company I worked for put me out troubleshooting after having me accompany one of their techs around for 5 days. I was proud to be doing this and the money was good but what I didn't realize was how wide the gap is between book knowledge and field experience. It took me years to accumulate the field experience that I think a better company with a more responsible outlook could have provided by making me carry another pro's tools for 6 months.
Lots of greedy companies might be willing to throw you out there before you are qualifyed to trouble shoot but you will only be stunting your own career by not getting the experience that a pro experienced in field work can offer.
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- Residential HVAC Troubleshooting

Postby Freon » Sat Apr 07, 2012 4:25 pm

You have a clue from your description of the problem... you press the contactor and things work. So it would appear the 25 volts needed for the contactor is not present OR the contactor coil is bad. To verify that, pull the main disconnect (you don't need 240 volts around yet), set the thermostat for Cool and see if you have the 25 volts AC at the contactor coil. If you don't have 25 volts at the contactor coil, the next question, tracing back along the 25 volt supply, is does the thermostat have 25 volts at the Y terminal? Turn off all power to the furnace/system, ALWAYS, so you do not inadvertently cause a short that fries a circuit board. Carefully remove the thermostat cover and find the Y and C connections. The Y is the 25 volts for the AC and the C is the common (return voltage on an AC circuit). Now turn on the furnace/system and measure the voltage between Y and C.

If you have 25 volts then the next question is where does it disappear between the thermostat and the AC condenser? Sometimes the control wiring will break and the insulation will stay intact. The break will usually happen close to the connection at the thermostat and can be anywhere the control wiring is exposed at the condenser. Weed trimmers are notorious. Using your ahnds you can feel the wire and find the break, if that's the problem. Good luck. Think of how commands in the house flow to the equipment via the thermostat and you'll be fine. Remember when you find the problem to reconnect the AC condenser disconnect. Good luck.
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Postby heatseeker » Mon Apr 09, 2012 8:28 am

if you had time to go on the internet and ask this question chances are customers best interest are not being considered. On those grounds


I refuse to answer.
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Postby moshei » Thu Apr 12, 2012 9:04 am

You have to find out what's the main problem on that..!
Check everything and make surfing as well..!
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Postby Edward » Sat Apr 21, 2012 11:31 pm

Keep looking into the control voltage of the contactor. The best thing you are doing is asking for help. We all got started somewhere and unfortunately probably in the same situation you are in. Keep asking questions and reasearching for your answers, you will always remember these times and learn much from them. More so than you will ever be taught. Keep your head up and confidence in what you've learned thus far. I wish you the best of luck.
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Postby heatseeker » Mon Apr 23, 2012 9:39 am

tHIS DUDE is long gone also, probably a diyer trying to disguise himself as a green tech. Five days ride along and the company put him out as a tech. Yea RIGHT>
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