Suddenly A/C or Furnace won't turn on...???


Old 05-01-07, 05:53 PM
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Suddenly A/C or Furnace won't turn on...???

I got home from work today and my house was a little warm. I went to check the thermostat and it showed a current temp. of 75 even though it was set to 70.

I reset the thermostat and tried again. No luck. I went out and checked the breakers and they were on, but I did go ahead and flip it off and back on again. No luck.

Then just to see, I went ahead and set the temp. on the thermostat to 80 and changed it to heat. The furnace is not coming on either.

When I set the temp. and click HOLD on my therm. I hear that little click that happens just before it actually kicks on, but then it doesn't kick on.

I have no idea where to go from here. Any information on how I can troubleshoot this would be greatly appreciated. Thanks!
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Old 05-01-07, 05:59 PM
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Does the A/C compressor outside kick on?

Do you have power at the power receptacle powering the fan?
Old 05-01-07, 06:53 PM
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Question update

Please forgive my ignorance...if by A/C compressor you mean the big box in the back yard with a fan that spins then no, it does not turn on.

As for testing power there I know my dad has a little tool he uses to see if he gets power to things...I'll have to get that from him tomorrow. Anything else I can do now?
Old 05-30-07, 06:35 PM
Join Date: Feb 2007
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I have this same problem.

The a/c and heat (furnace) just stopped working completely. I've checked the breaker and that is not the problem. Can someone tell me where I should be looking for the problem?
Old 05-30-07, 07:52 PM
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i can tell you what the deal with mine was. when i take the door off the furnace there's a little black button that comes un-pushed...the door holds in pushed in. under normal circumstances if I have the door off I can push that button on and the thing will fire up.

i messed with that button a whole bunch, took the door on and off over and over and never got it to work. my dad came over to look at it, took the door off, pushed the button a bunch and the thing kicked right on. i was pissed...though happy it worked again. heh.

Well, a day later it stopped again. I took the door off and pushed the button in and out...nothing. I thought to myself what EXACTLY did he do. It was rapid fire pushing of that button. I went back and rapidly pushed the button over and over and after about 6 pushes it fired up. after it fires up again then it works like normal for awhile.

it actually hasn't turned back off again since that next time. no idea what the problem was (is) and no idea if that will help you. but you might give it a shot if you see a little black button.
Old 01-25-14, 06:43 PM
Join Date: Jan 2014
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Here is another option when your AC and Furnace wont turn on.
I am not an HVAC technician but they really aren't too complicated up to a certain point. Heres each step I did and where I ended up finding the problem.

AC and Furnace stopped working entirely
Keep your thermostat on during this entire process (I chose ac so I wouldn't piss myself when the gas came on)
1) turned on thermostat (it clicked)
- batteries good
- multi meter'ed the red wire and the other colors (got nothing close to 15-25 volts)
- tried crossing the wires (shorting it out "short") to see if it would kick on - nothing

2) went and tripped all the circuit breakers turned them back on (still nothing)
3) yelled at kids and ex-girlfriend a little bit (sorry missed fishing for this crap)
4) pet my dog (he never does anything wrong)
5) tried multi meter on circuit panel (watched youtube video) to see if the breakers were bad but still holding in the on position - nothing all was good - getting power to circuit panel
6) checked fuses outside for the "quick disconnect" located next to the ac unit (big box with fan outside) - watched youtube video
- put multimeter on ohm setting and touch leads to both ends and should read 000's not OL - OL means their bad fuses - nothing, fuses are good
7) Ate tacos
8) My furnace has no drain switch (its old) yours may....**important, look on youtube
- its a device attached to the drain pipe usually around the bottom (duh drains are lower than electric parts) if the switch is bad or the drain is clogged its shuts unit down - I dont have one so I moved on after looking for it
9) looked at my power meter to the house to see if it was running really fast (could mean an overload) nope its running slow
10)took all the covers off the furnace and started testing the wires (nothing turning on its likely a power problem power=things turning on
- started with the biggest wires coming in (usually the 100-120 volt wires) had power
- tested power at the relay (box with lots of connectors) - had power
- checked wires off relay to thermostat (had 15 volts) fyi thermostat wires look the same at the furnace as they do at your thermostat
- checked wire going to fan - no power with thermostat on ok got an issue lets break it down
- I had connected the hot 100volt wire to the fan wire (bing fan came on) ok but still need ac and furnace to turn on doesnt do any good if no heat but got a fan - kept going
- I found these two black wires medium sized labeled 1 and 2. One had 100 volts then other was giving 15volts. then connected at this black disk (only two wires) I thought it was a fuse. I shorted (connect the wires together) bam AC kicked on.
Unscrewed the disk and turns out its called a "therm-o-disk". No clue why the hell I got one (because I have a fan limit) but it was the culprit. Thank god their freaking cheap.

Some things I didn't worry about. I didn't need a thermocouple because my pilot light was running.
Didn't need to check the gas because the pilot was running and the AC wasn't working as well so it wasn't just a furnace issue.

Moral of the story. Watch all kinds of youtube videos and you too can become a HVAC repair person. Saved me a few hundys but I missed 66 degree fishing weather in Oklahoma so not sure if it was worth it. At least my dog was happy to see me and didn't need something fixed. Made family bow to my excellence lol. Updated face book status.
Old 01-26-14, 01:31 AM
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Welcome to the forums. really dug up an old one here. I sure hope the original poster got his furnace fixed seeing how this thread is almost seven years old.

Pretty funny post though.

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