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Phil
Phil, Mechanical Engineer
Category: HVAC
Satisfied Customers: 8512
Experience:  Retired HVAC/ Electrical & Boiler contractor. Industrial
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Trying to replace an old one stop simple comfort 3801

Customer Question

Trying to replace an old one stop simple comfort 3801 thermostat with Honeywell rth6350d. My old one had w1/o-b wire and w2 y1. Not blowing air since installed
JA: Did you double-check the thermostat's settings? And what about the filters?
Customer: Old system was
R - RED
C -BLUE
W1-O/B - ORANGE
Y1-YELLOW
W2-WHITE
G-GREENHad black and blue wires too, but not used
JA: Do you plan on doing the work yourself?
Customer: Ok, one by one: check the settings? As in: it was on cool, temp read 78, turned down to 75 and nothing happened
JA: Anything else we should know to help you best?
Customer: Yes plan on installing myself, trying to now
Submitted: 1 year ago.
Category: HVAC
Customer: replied 1 year ago.
Posted by JustAnswer at customer's request) Hello. I would like to request the following Expert Service(s) from you: Live Phone Call. Let me know if you need more information, or send me the service offer(s) so we can proceed.
Expert:  Phil replied 1 year ago.

Hello, I got a notice that you want a phone call, we can work in this dialog box for the amount of your deposit, or I can call, but thats a $25 extra.

Customer: replied 1 year ago.
Let's see if we can work through the dialogue box for now. New to this website.
Customer: replied 1 year ago.
Still there?
Expert:  Phil replied 1 year ago.

OK, it is unusual that any thermostat shows W1- O/B under the same screw terminal... those are generally different terminals. Can you verify that is actually the case on your old thermostat?

when checking basic function on a thermostat set to extremes, for instance when checking cooling, set it to 60F

Customer: replied 1 year ago.
on the old system, the W1 and o/b are the same terminal
Customer: replied 1 year ago.
Here's what we're working with now
Customer: replied 1 year ago.
Blue wire was C on old system, black and brown weren't used. We have a heat pump
Expert:  Phil replied 1 year ago.

http://www.honeywellstore.com/store/images/pdf/rth6450d-5-1-1-programmable-thermostat-installation-manual.pdf

See page 24, heat pump wiring, is that the terminal strip on your new thermostat?

Expert:  Phil replied 1 year ago.

This is a battery operated thermostat, you do not need the C wire, cut the bare copper tip of the wire off, double the blue wire over, and tape it to itself and poke the taped end back into the hole in the wall.

The other connections are

Red wire to R

White to W1

Orange to O?B

Green to G

Yellow to Y

White to W2

If the system cools when you set it to head we have to go into the programming and reverse the function of O/B

Expert:  Phil replied 1 year ago.

Ooops

If the system cools when you set it to heaT we have to go into the programming and reverse the function of O/B

Customer: replied 1 year ago.
Okay, trying that now. Sorry, took a minute and kicked me off the screen when I checked the PDF but yes that is our wiring layout
Customer: replied 1 year ago.
You told me to put white in W1 and W2? I have W, and I have W2. In the old system, white was W2
Expert:  Phil replied 1 year ago.

my mistake, put white in W2

Customer: replied 1 year ago.
That's how I had it. Breaker on, ran through setup and set manually to 60. Heard a click at the thermostat, but nothing happening with the handler
Customer: replied 1 year ago.
Which is the point where we went online :)
Expert:  Phil replied 1 year ago.

Tell me if the system was working when you had the old thermostat in place OR if the system was not working and you assumed that the thermostat was bad and are replacing it?

Customer: replied 1 year ago.
System worked fine with old thermostat, just couldn't program it
Expert:  Phil replied 1 year ago.

Did you turn off power to the furnace before changing the thermostat? if not, they you probably blew the 3 amp fuse that most air handlers have fit into their printed circuit card.. its an automotive type dual spade terminal type

Customer: replied 1 year ago.
We turned all breakers off for the AC before changing the thermostat
Expert:  Phil replied 1 year ago.

Locate the thermostat wires where they attach to the printed circuit card, and measure the voltage between the R and C terminals... it should read 24v, if not look for a fuse in that circuit

Expert:  Phil replied 1 year ago.

Sometimes an electrician marks the breakers AC that serve the outside unit ONLY, but not the air handler which is where the 24volts comes from that operates the controls

Customer: replied 1 year ago.
Hmmm.....you just got beyond me. PS we're in Florida, did not look for/realize there were separate breakers for the furnace, which I did not turn off first.
Expert:  Phil replied 1 year ago.

Do the voltage check between R and C in the air handler at the thermostat wiring terminal strip

Customer: replied 1 year ago.
What would I use to do a voltage check? I do not have the handler open.
Expert:  Phil replied 1 year ago.

Use a multi meter, $30 type will work.

Expert:  Phil replied 1 year ago.

The cheaper ones can be dangerous

Customer: replied 1 year ago.
do not have such a gizmo.
Expert:  Phil replied 1 year ago.

Hardware store or big box store electrical dept,

Expert:  Phil replied 1 year ago.

I will hold the question open for you until you get back with a multi meter,

if you need instructions go to youtube and search box 'multimeter' for a few dozen tutorials

Expert:  Phil replied 1 year ago.

I am in all day tomorrow as well, starting at 7 am

Customer: replied 1 year ago.
Thanks for holding it open. 10pm on a sunday means can't get a multimeter til tomorrow. Trying to rewire old plate to see if the thing comes back on (i.e. not a fuse problem)
Expert:  Phil replied 1 year ago.

Good idea, I will see you monday as needed.

Customer: replied 1 year ago.
yup, no power. fuse blown. will try again tomorrow.
Expert:  Phil replied 1 year ago.

I will be in all day 7am to 9pm mostly

Expert:  Phil replied 1 year ago.

buy 3 extra fuses in case you need them

Customer: replied 1 year ago.
Got into the unit and the fuse was clearly blown. New fuse in, system is cooling. Thank you!
Expert:  Phil replied 1 year ago.

Good work!

Its time to locate the 'Finish and Rate' link and click on it, the company only pays me for my time expenses if you rate...I will appreciate that very much. thanks!

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