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Category: HVAC
Satisfied Customers: 14880
Experience:  15yrs in the HVAC industry with certificates and degrees.
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I'm in the process of replacing a totaline thermostat for my

Customer Question

I'm in the process of replacing a totaline thermostat for my Carrier HVAC unit. The old thermostat went blank and stopped working. When I plugged the new one in it started buzzing fairly loud. I quickly unplugged it. Any ideas ?
JA: Just to clarify, do you think this is a larger HVAC problem, or something specific to the thermostat?
Customer: I have 5 thermostats and 5 zones all work
JA: Do you plan on doing the work yourself?
Customer: Yes I'm changing the thermostat myself
JA: Anything else we should know to help you best?
Customer: Have you ever heard a thermostat buzz when hooked up? All the wires are connected as they were with the old thermostat and are the same as all the other thermostats. The replacement thermostat is the identical part number as the original
Submitted: 1 year ago.
Category: HVAC
Customer: replied 1 year ago.
Anyone there?
Expert:  HVAC Guru replied 1 year ago.

Hello and thanks for using this service, if you have been waiting do not worry or get upset. I am HVAC Guru an extremely experienced tech on the site and I try to get to as many customers as I can. I just picked up your question now. NOTE it takes time for me to type research and add links so please wait for me to respond back I can only do this so fast. Secondly I am not paid anything until you rate my service good using the STAR RATING LINK at the top of your page, the money is paid to the site not me directly.


I am sorry no tech got to you sooner,

What likely happened is the low voltage fuse in the furnace or airhandler blew. There typically is a SLOT STYLE 3-5AMP FUSE on the board itself inside the furnace/airhandler like this.


If that is burned out all power to the thermostat will be lost. 95% of all units use some sort of SLOT FUSE or inline BUS STYLE FUSE to protect the low voltage circuit. You need to find that and change it out. If you just bump two wires together you could have just popped it without even knowing it. Now if for some reason your unit does not use a fuse often the board will be damaged due to the short. You would need to confirm you have 24 volts to the board inside the furnace/airhandler with a volt meter to make sure though.

Note if you have a condensate pump check the float and make sure the pump is not full of that could cut low voltage power to the unit as well if the pump is not working and full of water.

All I ask is please use the Star Rating Link at the top of your page before leaving, that is the only way I am paid anything through the site and that will also get you a DIRECT LINK emailed to you to get back to me! are greatly appreciated so thank you very much for using this service. If you have any other questions just post back to me here anytime!

Customer: replied 1 year ago.
I don't think you read my question but thanks for the reply
Expert:  HVAC Guru replied 1 year ago.

The thermostat was buzzing?

Customer: replied 1 year ago.
In my question I state that I have 5 thermostats and 5 zones all work fine. 1 thermostat went blank so I got a replacement it buzzes, looks like they sent me a lemon the transformer inside the thermostat is buzzing. HVAC unit still works fine even with the buzz. Thanks for your attempt to try and help
Expert:  HVAC Guru replied 1 year ago.

Yes nothing else that I can think of would cause the thermostat to buzz other than a bad thermostat...there is not much else that can cause that issue. I would agree the thermostat is bad.