Carrier 40aq024300BU (V)?..transformer

someday31

I need to replace a blown transformer on a carrier 40aq024300BU....anyone know what the part number is, where I can find one? Thanks. Also...anyway to get the system running for heat! Here are the numbers I got off the old transformer 308346, could be 303346 hard to read. 60VA 24 volts Model number 40AQ024300BV Serial number:53A58192

Doc Holliday

any make will work, just as the VA, input and output voltage is the same. Sorry but no way to get heat without that low voltage transformer.

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Thanks.

someday31

Thanks for the reply! So if I bring the old one to a hvac supply house they should be able to get me what I need? Do I need to know if its 120 or 240volts?

Doc Holliday

Have your furnace model number with you just in case but these days it might simply be a three for one step down transformer. The wires you don't use you simply wire nut/cap off. They're called multi tap transformers, should come with 480, 240 and 120 volt wire taps which would be your input (use 120, cap off 480 and 240) and come out 24 volts. Or they'll give you a single tap 120 volt transformer as gas furnaces are 120 volt.

Just take it with you, it's not a big deal. Try Grainger if you have one near you.

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Thanks.

JScotty

Yeah you're probably going to get a multi volt one. It's pretty easy to hook up as the guy above described. And pretty much if you have an electric furnace it's almost always 240v gas or oil furnaces will always use 120v

Doc Holliday

My name Is Doc, Doc Holliday. You can call me Sir.

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Thanks.

someday31

So this morning I picked up a mars 50327 this morning as thats all I could in stock locally. So my old one is ht01aw230 carrier, 60va 24vac and the 230v was used, not the 200v. I hooked up my mars as follows, used the black to black and red to the orange on the mars. Is that right? Cause what happened was it powered up and once I turned on the the blower and heat the transformer started to smoke a bit and now doesnt work, and the reset doesnt do anything, think I blew it. Did I hook it up right? Since I have the old one out and now know the exact part number will order the exact replacement...but could it be that it was hooked up wrong or does it matter that the mars was rated at 50va and the original is 60va? The blue wire wasnt used on the old one. Thoughts...

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JScotty

Assuming this is what the sticker on your transformer says I think you hooked it up wrong. Sounds like you're saying you used the black & orange wires. The way it should be hooked up is one high voltage wire to common (white) the other to 240 (orange).

64pvolvo1800

Sounds like you went too small. The 60VA is the power rating and you went 15% lower or more. I would say you should throw and ohmmeter across the low voltage side and look at the resistance. You should have more than 10 ohms and likely it's barely over. Higher is great, lower is bad!
If its lower, then you probably have a short that took out the first one. If it was a short though, it would've smoked instantly. How long did it run?

JScotty

Just an edit on this, looks like this pic is actually of a different model mars transformer. Post a pic of this sticker on the one you installed & I can double check for you.

JScotty

From all the picture I found online of the transformer he bought it looks like it has a built in breaker, so if it shorted he should be able to reset it, but it shouldn't have smoked either so I doubt that's it.

64pvolvo1800

Just to clarify, throw the meter across the low voltage side wires with the transformer disconnected, not reading the transformer.
And while you're at it, take a reading across the two input wires and the two output wires ON the disconnected xfirmer and we can tell you if it's smoked.

someday31

Here is the pic of the wiring of the transformer I got. I originally hooked it up using black and orange on the transformer. Today I tried using the white and orange as mentioned on here to do. When I did that it worked initially but then I could the transformer humming and then it popped and tripped the breaker! That was all within 25 seconds. Im not sure if I mentioned but with a meter I tested my leads going into the transformer, when un hooked and my power input is 2 120s. I held black lead of the meter to the air handler frame and tested the 2 wires with the red lead and those were my results. I did get power out of the transformer initially as mentioned until it blew. So do you guys think when I get the exact part tomorrow it get me running or does this prove something is going to just short out a new transformer? Dont forget my original one used the 230 volt terminal output. Thanks.

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beenthere

Thats cause you wired it wrong the first time.
You should have wired the transformer orange to line black, and the transformer white to line red. You also got a smaller transformer then you should have.

Get an inline fuse also if the new transformer doesn't have its own.

64pvolvo1800

White and orange for 230 input is correct. But, with the secondary low voltage wires disconnected, measure the resistance of the two wires going away from the transformer. With the transformer disconnected entirely, measure resistance of the white to orange on the transformer and also the output leads of the transformer.
White-orange = _____ohms
Low side = _______ohms
Load wires tfrom the xfirmer = _____ ohms.

This will tell us what hapoened and why.

One last thing, measure between the body of the transformer to each lead. Should be open or many Mohms