Tried to replace Thermostat, now A/C nor Heat works (or fan)

[mindflux98]

Well my roomate and I tried to replace our thermostat with a programmable one. We turned off the breakers, labeled all the wires and got to work. This T-stat is for heat/cooling with a heat pump and emergency heat.

When we put the new t-stat in, we had 8 wires off the old T-stat. The manual said to just use 5 (so did their 800 help line).

Here's what we took off.

R = Red Y = Yellow W = White X2 = Black T = Brown O = Orange G = Green B = Blue

What we hooked up:

R = RC Y = Yellow W = W1 O = Orange G = Green

We taped off Blue, Brown and Black (as per the 800 tech's recommendation).

Reset all the breakers to ON....

Upon getting it all set up nothing worked, I couldn't even manually turn the fan on.

So.. this is where we currently sit.

I put the Old Tstat back in PRECISELY how it came off. All the wires went where they needed to be. Nothing! Not even switching the t-stat to emergency heat the red light doesn't illuminate.

I tried to use a multi-meter at the T-stat to check the 24v AC off the Red wire.. but I'm only reading like .03 volts.. (I'm not sure if I'm not using the multimeter right or what?).

Anyway.. It's hot as heck in the house and nothing I've done has helped.

Has anyone got suggestions?

-R

[Al Moran]

Find the air handler, that's the part that puts the air in the house. Look for a three or five amp flat fuse. If it's popped then replace it, if you do not find any fuse then replace the transformer. When you replace the transformer make sure you put a 3 or 5 amp fuse inline with the red 24v side of it.

[Ryan]

Thanks, the only fuse I've found is this:

I cannot see if it's popped since it's got a laminant over the glass. It's a BUSS fuse, not a flat fuse (like cars use).

[Al Moran]

If you cannot find the buss fuse then just cut the old one out as a fuse is a fuse is a fuse. I saw your post on the hvac forums. Your fuse is dead if your reading ol on the meter. As I said, cut the fuse out, go to the nearest auto parts store and get two spades and at least 4 or five 5 amp fuses. Where you cut the buss fuse out put a spade on either side then insert the 5 amp flat fuse. Make sure you get some extras in case you have a short somewhere. Was the system working before you changed the stat? If so then you did not turn off the right stuff before you installed the stat and you shorted some wires together while doing so. If the system was not working before you changed the stat then something else is going on.

[Ryan]

I can remove the buss fuse.. as I was carrying it around all day hopping from store to store trying to find someone that had it.

The central unit has a spot where I just put the buss fuse in, turn the knob to lock it in. How would I replace that with Spade Fuses?

The system WAS working before I replaced the T-Stat. I shut down all the breakers, replaced it as per the instructions (taped off three wires I was told not to use).. fired the system back up and have been A/C less since Mid Saturday!

I see grainger carries the BUSS fuse.. but I may have to wait till tuesday if they do not have in stock on monday.

Thanks for your advice.

[Al Moran]

Just cut the fuse holder out and crimp in a spade on each side of the wire that you cut out the buss fuse holder from. Install the 5 amp fuse in the spades. Take the wires that you taped together and un tape them.

[Ryan]

Al..

The buss holder is sort of like a 'socket' so to speak. The side I see is the 'end'. It's not like:

--- [ FUSE ] ----

It's like BUSSFUSE==](socket)--------------(wire)--------------------

if that makes sense? if not I can take a picture and perhaps email you.

Since I am renting this property I'm sure the property manager would go ape-s*1t. He's supposedly got someone scheduled monday to come check it out.. but I dont want to sit in the sweltering texas heat any longer than I have to.

[Al Moran]

Guess your screwed then until the ac guy gets there. I went back and read your original post. The shorted fuse is being caused by the wires you taped together, also, the other problem is that you don't have your aux heat wired into the stat if you have brown and black not connected to anything. One of the wires, either black or brown, is for the second stage heat, the other is for aux heat. The blue wire is the common.

[Ryan]

I didn't tape them together, I just taped over the exposed wire so they'd do nothing. But even then it sounds like I needed the other 3 hooked up huh?

Dangit!

Well the stock t-stat is back on, wired up with all 8 wires. I guess I'll have to cope until I can get a new fuse or the mgmt company can come out.

[CJT]

You said you had a multimeter. How many ohms is the fuse?

[Ryan]

It was just reading "O.L".. it wouldn't report any ohms.

[CJT]

If that's the same thing it reads with nothing connected to the leads, but it reads zero (or nearly so) when the leads are connected together, then the fuse is blown. Otherwise, either you're not on the ohms range, the meter is shot, or its battery is dead.

You can probably get a replacement at your nearest auto supply house.

[Ryan]

Alright, I got some new fuses (although they wont work in this thing apparently). I can get the audible tone to beep with those, or 0.00 if I'm going for an actual reading from the fuse...

Where as the one in question reads "O.L" or no tone. So.. this is likely the culrpit, and rare to boot.

[CJT]

The picture looked like a garden variety fuse. If you take the old one with you to an auto supply house (or Radio Shack), I bet they can get you going.

[Ryan]

This picture?

It sure does, except for that purple KNOB that doesn't come off the end. I've gone to lowes before they closed and got some 250W 4amp fuses.. they're a HAIR shorter than this GMQ fuse and don't have the knob (or the little tangs on the knob end to 'lock' it into the BUSS holder on this unit..

Here it is in the grianger catalog.

Thanks

[CJT]

I guess I've just learned something. :-)

I've never seen one with an integral "knob" before. I guess that's a ploy for them to make additional $$$.

[Ryan]

I really want to call BUSSMANN up on monday and ask them why they had to destroy my weekend... but I wont get anywhere.

I'm going to grainger at 7:30am to get these fuses (they have 3, thankfully). I'll drop one in and flip all the breakers back over to ON and hope for the best..

This fuse is on the blower box, near all the wiring coming in from the T-stat.. I'm guessing since this fuse is janky that's the reason I can't read 24V off the "RC" terminal?

Just trying to think ahead.

[CJT]

Sounds right. But in my experience, it's rare that I only blow one fuse, so I'd certainly buy all three!

[Ryan]

Well I'm not sure what else I could have blown. This is the only visible fuse I see.. I guess I could have popped a transformer, in that case I'll need my technician (which hopefully comes out monday) to repair.

[Tony Hwang]

Hi, What is shorted fuse? Problem seems to be that OP'er did not mention RTFM. Usaually if manual did not come with the new 'stat, it's dlwnloadable. Haste makes waste. Lesson learned.