Need HVAC/Furnace Help - Furnace Dead

[asmo]

So a few weeks ago I bought a fancy new Ecobee3 thermostat to replace the Honeywell that I had. I hooked it up and everything worked great except the original builder only ran 18-5 between the thermostat and the furnace - so I couldn't hook up the humidifier since I didn't have enough wires (the old Honeywell used a THM5421C EIM to go from 7 wire to 3). So no big deal we went without a humidifier for a few weeks until I could run some 18-10 between the thermostat and the furnace (and humidifier).

So flash forward to last night. I run some 18-10 between the thermostat and the furnace (no easy task). I hook all the wires up and nothing - furnace wont even power on. I check all my wiring and the safety switch and everything looks good. I test for voltage across C and R at the furnace and I get nothing. I jumper R/W and nothing, I jumper R/G/W and still nothing. I do hear 120AC going into the furnace (hum), but it doesn't translate into anything. I also don't get any lights on the furnace control module.

Anyone want to help my understand what the hell I am doing wrong. I really hope that the furnace control module didn't puke just because I put some new wires in.

This is the furnace end before I started:
64100

This is the furnace end after I replaced the 18-5 with 18-10:
64101

In both of the above, the top W (going to Y) and the bottom B are going to the safety switch.


This is the thermostat end (no difference before and after other than different wires -- still the same colors):
64102

This is the furnace control module (its a RUUD):

64103

Any thoughts? I really don't want to have to pay for a Sunday emergency call, but I leave tomorrow and need to have heat in the house before I go.

[Mazin]

Paging Hghclsswhitetrsh

[hghclsswhitetrsh]

Check voltage going into and leaving the transformer, both 120v and 24v

[Wulf202]

You tripped a fuse. Check for a small one on the board or somewhere inside and check the ssu. The transformer might be fried? Hard to tell without real tests. A sound does not mean you have power.

Get multi meter and learn how to use it before you cost yourself some serious money.

[hghclsswhitetrsh]

Is there anyway possible that you damaged the wiring by pulling the new one, creating a short. I'd start by pulling the wires off both ends and test ohms Red to green, red to yellow, red to blue, red to white red to green. Then green to yellow green to blue green to white etc etc etc.

Also I didn't see a fuse on the board, is there and I just missed it?

[asmo]

Check voltage going into and leaving the transformer, both 120v and 24v

To do that am I going to need to get into the safety switch? I am looking for where I can attach my voltmeter leads to. Is there someplace easy you would recommend.

Thank you for the help!

[hghclsswhitetrsh]

You tripped a fuse. Check for a small one on the board or somewhere inside and check the ssu. The transformer might be fried? Hard to tell without real tests. A sound does not mean you have power.

Get multi meter and learn how to use it before you cost yourself some serious money.

Not all furnace control boards have fuses. The SSU fuse wouldn't be tripped from a low voltage short.

[asmo]

Get multi meter and learn how to use it before you cost yourself some serious money.

Does a MS in EE count? ;)

[hghclsswhitetrsh]

To do that am I going to need to get into the safety switch? I am looking for where I can attach my voltmeter leads to. Is there someplace easy you would recommend.

Thank you for the help!

Are you talking about the door switch? If so then yes, if operating and wires correctly 120 volts cannot get to the board/transformer with out being pressed in.

[asmo]

Are you talking about the door switch? If so then yes, if operating and wires correctly 120 volts cannot get to the board/transformer with out being pressed in.

Yup got that part.

Just looking for a good place to test before the transformer. Everything is sealed up. I'll go back to playing around and see what I can find - good call on measuring the resistance between the pairs.

[SideShow Bob]

Before getting too involved, make sure your wires at the furnace are making good contact.

Esspecially the bottom ( in photograph ) blue wires ( or are they gold ? ) looks like you may have pushed the second one in too far and are pinching down on the insulation and not copper as the first one is.

[asmo]

Okay continuity test on all the wires in the 18-10 came back good. So this is definitely at the furnace. Thank you everyone for all your inputs.

[asmo]

Anyone got one of these handy? Reads 250V @ 2A.

Tiny little bugger.

64105

[Great-Kazoo]

Anyone got one of these handy? Reads 250V @ 2A.

Tiny little bugger.

64105

Radio Shack [LOL]

On a serious note. For anyone reading this who has to replace thermostat wires. Tape the old to new before pulling the old out.

[hghclsswhitetrsh]

Believe it or not homedepot has them.

[asmo]

Believe it or not homedepot has them.

Negative on Home Depot, Lowe's, Ato Zone, and Napa. Rat Shack is next. If all else fails I will rewire it to take a larger diameter fuse with the same rating.

[hghclsswhitetrsh]

Hmmm. I got some from the Home Depot in Lakewood. But that doesn't help you much. Better find the short or you'll have the same result.

[asmo]

This one is physically smaller than a 5x20, which many people carry. No biggie - I'll do a 1 1/4 inline, and put a 250V @ 2A in it.

Agreed on finding the short. I am hoping that it popped when I cut the existing wiring - I thought I had the power off when I did the cut, but I forget things a lot. ;)

[hghclsswhitetrsh]

[emoji106]🏻

[asmo]

SUCCESS.. The patient lives..

Thank you to all for providing input and helping me diagnose the problem.