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airheatman
airheatman, HVAC Technician
Category: HVAC
Satisfied Customers: 8064
Experience:  Furnace, A/C and heat pump specialist.
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I installed a new programmable thermostat replacing the old

Customer Question

I installed a new programmable thermostat replacing the old one that was not remembering the temperature it was set too. and triple checked that all wiring was connected properly and the new thermostat says that it is working but nothing runs on the units cannot even get the fan to turn on with the on setting
JA: Just to clarify, do you think this is a larger HVAC problem, or something specific to the thermostat?
Customer: thermostat as nothing tripped outside and there was no problem with the hvac before installation
JA: Do you plan on doing the work yourself?
Customer: if possible yes
JA: Anything else we should know to help you best?
Customer: its on the sensi wifi thermostat
Submitted: 4 months ago.
Category: HVAC
Expert:  airheatman replied 4 months ago.

My name is ***** ***** I am happy to assist you today.Give me a moment to look over your question and gather some information .I may need to get a bit more information from you.

Expert:  airheatman replied 4 months ago.

1. Did you turn power off before stating?(If not wires may have touched and blew a little fuse inside furnace or air handler)

2.Tell me what color wire went to what terminal on old and where you put them on new

3.Model on old and new thermostats.

We will go from here.

Customer: replied 4 months ago.
1. turned the units off at the inside breaker and checked that they were indeed off before beginning to remove the unit.
2 and 3.
old unit Honeywell Chromotherm III.
White wire connected to E and daisy chained with W2
Yellow wire connected to Y1 and daisy chained to W1
Red wire connected to R
Orange wire connected to O
Green Wire connected to G
Blue wire connected to CNew thermostat Sensi by emerson
White wire connected to W/E
Yellow wire connected to Y
Red wire connected to RH
Orange Wire connected to O/B
Green wire connected to G
Blue wire connected to CP.S. went through entire process reversing back to the old thermostat and it did not work either.
Customer: replied 4 months ago.
the red terminal on the old thermostat had a second red wire near the other that was bare and twisted into a circle like it had been attached at one time however there was no direct connection to it when i first opened thermostat cover
Expert:  airheatman replied 4 months ago.

White should go to W2.Lets change that and then look in air handler for a fuse that may be blown

Customer: replied 4 months ago.
which unit is the air handler? one outside?
Expert:  airheatman replied 4 months ago.

INdoor

Customer: replied 4 months ago.
sigh in my case that under the house.
Expert:  airheatman replied 4 months ago.

Do you have a volt meter handy.

Customer: replied 4 months ago.
Expert:  airheatman replied 4 months ago.

Check between RH and C and see if we have voltage.If not you will have to go under

Customer: replied 4 months ago.
no power. so i need to remove the cover to get to the fuses on the inside unit?
Expert:  airheatman replied 4 months ago.

THat is correct.Most newer units have a control board with a little 3 or 5 amp fuse.If you know or can get model on unit I can tell you where it is.

Expert:  airheatman replied 4 months ago.

Generic picture of board

http://i.imgur.com/UxPpnn4.png

Remove fuse to see if blown

http://i.imgur.com/kYe4Epz.png

Customer: replied 4 months ago.
I opened and found the 3 amp fuse running between the red wire which is not blown it is a model number B3BM-036K-B no circuit board that i can see.
Expert:  airheatman replied 4 months ago.

Next check transformer for 24v output.

Customer: replied 4 months ago.
tested dc volt 200 between the two points on this pic of the transformer
Customer: replied 4 months ago.
got .7 on it
Expert:  airheatman replied 4 months ago.

You sure meter is set right? If only 7vac transformer is bad

Expert:  airheatman replied 4 months ago.

Meter needs to be AC volts

Customer: replied 4 months ago.
27.9 volts
Expert:  airheatman replied 4 months ago.

OK we have to find where we are losing it.Lets see if it is leaving the air handler

Expert:  airheatman replied 4 months ago.

Look for a fuse in red wire.If no fuse check between Red and Gray leaving air handler

Customer: replied 4 months ago.
found the fuse and it is fine. could just be a bad connection between the line running to the thermostat and the linkage where the line splits off to go to the outside unit. going to cut all those wire back and reconnect see if that fixes it. this linkage is not in a box or anything to protect from moisture when i redo them should i put them in conduit box or at least wrap them in electrical tape?
Expert:  airheatman replied 4 months ago.

I would reconnect with wire nuts. Also make sure there is not a float switch or condensate pump in circuit between furnace and thermostat that might be breaking circuit.

Expert:  airheatman replied 4 months ago.

Update.The more I study the Sensi. I am thinking you may have been correct on the W/E

Most thermostats use W2 to energize heat strips as second stage heat (First stage being the heat pump).

So lets keep the White where it was.

Were you able to find a break anywhere in the circuit from air hander to tstat?

Customer: replied 4 months ago.
i rewired completely due to the old wire was brittle and I did not want to have to do this again. i wired it up on w2 and it is running do i need to change it back to w/e?
Expert:  airheatman replied 4 months ago.

AS long as it is working leave it as it is.Most thermostats use W2 as second stage.

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