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Sean, HVAC Technician
Category: HVAC
Satisfied Customers: 204
Experience:  Owner HVAC company
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I replaced batteries in the thermostat and now units wont

Customer Question

I replaced batteries in the thermostat and now units wont turn on
JA: Just to clarify, do you think this is a larger HVAC problem, or something specific to the thermostat?
Customer: i think its a reset issue
JA: Do you plan on doing the work yourself?
Customer: yes
JA: Anything else we should know to help you best?
Customer: no
JA: OK. Got it. I'm sending you to a secure page on JustAnswer so you can place the $5 fully-refundable deposit now. While you're filling out that form, I'll tell the HVAC Technician about your situation and then connect you two.
Submitted: 1 year ago.
Category: HVAC
Expert:  Phil replied 1 year ago.

Hello, first off make sure the batteries are installed in the correct positions.... we all mess that up from time to time. Clean the battery terminals with an alcohol swab while you have the batteries out

If the system still does not work. reverse them all, that is deliberately put all the batteries in backwards, wait 5 minutes then reinstall them in their correct positions.

If that fails, tell me a lot about your technical skill sets and if you have a multi meter or not so that I can coach you most effectively.

This could easily be a reset issue if it was over 100F outside when the unit failed, tell me about that please.

We can go from there

Customer: replied 1 year ago.
it was close to 100 outside. I think just the battery being corroded maybe did something. I replaced then and the thermostat works great. Just won't seem to turn on ac or at least feel it inside. I haven't gone outside to check unit though. I'm at work right now. But should b back home in maybe 3 hours. I will try reversing the batteries if you think that will help turn on the motor. But therm seems to b working. I flipped the breaker to see if it was that and it wasn't.
Expert:  Phil replied 1 year ago.

Hello again, if the breaker is *tripped*, 'flipping' it won't work to reset it. You have to turn it off, then force it hard toward the OFF position, *that will reset the breaker. Then turn it back on.

Tell me about how old the unit is, and if you have ever cleaned its outside condenser coil or not....a dirty coil will cause the unit to trip its high pressure safety cut out switch on a 100F day.

Depending on the make and model of the outside unit that reset can be reached through a 1 inch hole punched in the sheet metal, or you have to access the electrical controls area inside the unit itself.

Tell me a lot about your technical skill sets so that I can coach you on how to check out the thermostat. (its done by accessing the wires that come from the thermostat and end up inside the blower compartment of the furnace... if you can send me a photo of that terminal strip I can coach you on how to check the thermostat out)

To attach a photo use the paper clip icon at the right end of the tool bar, or the attach files link to the left of your send button.

We can go from there

Customer: replied 1 year ago.
Thanks. The unit is a rheem and its 4 years old. My skills are ok. And im kinda daring. Lol. I will b home in a couple of hours where I can go out and see the unit. Ya. Breaker was not tripped. I pushed it off hard waited a bit and then switched it back on
Customer: replied 1 year ago.
I had a friend suggest to just buy a new therm being that sometimes the corroded battery can take out other things.
Expert:  Phil replied 1 year ago.

Hello again, your friend is not far off the mark, corrosion does a lot of damage.

Getting the right thermostat for your type of system that does not require 40 pages of fine print programming however is not always easy.

Look for a thermostat with one page of installation instructions, costing $50 or less. if yours does not have a C terminal the one you buy must be entirely battery operated. If yours has a C terminal it can be powered from the furnace and the batteries are only there for back up.

We can go from here without a time limit.

Customer: replied 1 year ago.
Thanks. But the therm that is on the wall looks like the 200$ one. So I bought one that is a newer model. But not gonna take it out of package until I realize it will b a good fit. Both honeywell. The current one only 4 years old. About 3.5 inches tall by 4 or so inches long. 7 day programmable. Heatcool. The new one I got is those smartphone one. Hoping it will b good since then can change temps from wherever.
Customer: replied 1 year ago.
That looks like current one
Customer: replied 1 year ago.
This looks like new one
Expert:  Phil replied 1 year ago.

I need the full model numbers of both thermostats to tell if they are compatible..

and.. if you can pry the existing thermostat off of its wall mounted sub base and tell me which color wires go which color terminals, I can help you.

Customer: replied 1 year ago.
Old and new models
Expert:  Phil replied 1 year ago.

Hello, thanks for the attempt but the photo of the old thermostat arrived too blurry to read, and there was no picture of the *wire* terminal connections on the existing thermostat sub base... at this rate, with me coaching you this will take hours.

I will opt out so that other experts here can take a shot at helping you.. if everyone else declines, I will help you for up to 5 straight hours of coaching but only if you provide a positive rating..... lacking that I loose my shirt on an involved deal like this.

Expert:  Sean replied 1 year ago.
I can offer my assistance what have we figured out so far?Please remember at the end to give me a rating so I can be paid for my time..sound good ?