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Brian HVAC Guy
Brian HVAC Guy, HVAC Technician
Category: HVAC
Satisfied Customers: 945
Experience:  I have been an HVAC/R mechanic/technician for 30+ years.
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Our thermostat was blank, no power, etc. we looked it up and

Customer Question

our thermostat was blank, no power, etc. we looked it up and looked like a fuse, we replaved it, but right away, twice, it keeps blowing the fuse to the thermostat, so cant get thermostat to turn on at all.
Submitted: 1 year ago.
Category: HVAC
Expert:  Brian HVAC Guy replied 1 year ago.

Hi Dan, I'm Brian and I'm here to help!

This is a pretty common problem but finding it can be tough sometimes. Can you give me a little more info please? Anything that's changed with your ac or heat system recently, new t-stat, service performed, etc... What is the brand and model numbers of your ac/heating equipment?



Customer: replied 1 year ago.
Hi, no, it has been working great! we are in FL, have had the heat on for weeks now, then recently, had the air on, they had it all set to off just for one morning, and when we went to turn the AC back to on later that day, that's when it was blank and would not let us select anything, no power to it at all. Looked it up and went and bought the little fuses, but everytime I put it in, it blows right away. the interior handler is nordyne model GB3BM-042K-10A, thermostat is a totaline
Expert:  Brian HVAC Guy replied 1 year ago.

Great, thanks for the info Dan. That helps a lot. It sounds like since the fuse blew when you turned on your ac that it is probably ac related. The most common cause for this is the thermostat wire outside between where it exits the wall and enters the ac unit has become compromised and shorted together so I would look carefully at that first. The symptoms also lend itself to that since this happened when you haven't even been running your ac! The next likely cause(s) are in the ac unit itself and could be failed compressor contactor, a rubbed wire shorting through the insulation, a failed time delay (if equipped) and a few other less common issues. We can do some testing without any meters by disconnecting low voltage wires to see if the fuse still blows. This is just process of elimination. The simplest way to find it is to find the short to ground with an ohmmeter. So check the wire outside and turn power off the the ac unit and remove the control panel and look to see if something doesn't look right and let me know what you find. We can go on from there.



Customer: replied 1 year ago.
Thank you! Dan had to run to a job, so said when he gets back later today, will do what you listed above and see, and write back then. Thanks ! Michelle (wife)
Expert:  Brian HVAC Guy replied 1 year ago.

Very good then Michelle, I'll look for a post back later. Thanks much, -Brian

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