Brand new AC will not come on

[Papadod7]

Hi everybody,

We just bought a domestic brisk II brand new. Our furnace and AC are hooked up to the same thermostat and control board. The furnace works great, our old ac did nothing when we turned it on. It looked really old so we bought the new one.

Problem is, when we plug the brand new AC unit it, it still does nothing! We hear the thermostat click, but nothing happens in the unit. All the fuses in the trailer are still good. What could the issue be??

[bsmith0404]

What about the circuit breakers? Fuses are 12v systems, circuit breakers are for the 120v. Your AC is 120v

[Papadod7]

All the fuses are good. The circuit breakers are 120v.

[bsmith0404]

Originally Posted by Papadod7

All the fuses are good. The circuit breakers are 120v.

Your AC is 120v. The fuses don’t have anything to do with the AC. Are your breakers all good? Try resetting them

[Papadod7]

All the circuit breakers are good. Reset each of them. Still nothing.

[chuckster57]

Ok. Have you verified 110VAC to the AC control box?

Silly question, is the roof unit plugged into the control box?

[Papadod7]

AC is plugged in, haha.

How do I check if it is 110VAC to control box?

[chuckster57]

I have a couple different non contact testers, or you could use a volt meter if your comfortable around live circuits.

[Papadod7]

Im confident there is power to the control box because the furnace runs through the control box, and it works fine.

[chuckster57]

Originally Posted by Papadod7

Im confident there is power to the control box because the furnace runs through the control box, and it works fine.

Furnace is 12V and the thermostat is 12V. When you ask for cool, it should engage a relay in the control box that allows 110VAC to the roof unit

[Papadod7]

Hmm okay thank you so much.

But how do I check? I can buy a voltmeter. What do I do with it?

[chuckster57]

Open the control box and look for the Romex connections set VOM to AC volts and place red (positive lead) on the black Romex wire and the negative lead (black) on the white Romex.

Often times the Romex is wire nutted to the stranded wire in the control box.

[Mike&Sandy]

If the AC isn't working with 2 units, are you sure you're getting 12v at the thermostat?

[chuckster57]

Originally Posted by Mike&Sandy

If the AC isn't working with 2 units, are you sure you're getting 12v at the thermostat?

If the furnace is working, odds are the thermostat isn’t the issue, but that will be the next test after verifying 110VAC to the control box.

[Papadod7]

Chuckster, this info is treasure but is a foreign language to me. Is the Romex connection the green and yellow wire?

[chuckster57]

The Romex is the 3 conductor in a plastic sheath. Most likely coming out of the ceiling, and it’s fairly stiff. Your 12V wire is usually stranded but the thermostat wiring is usually thin solid copper wire. Often times 5 wires in a sheath.

[chuckster57]

Originally Posted by Papadod7

Chuckster, this info is treasure but is a foreign language to me. Is the Romex connection the green and yellow wire?

Most often black (line) white (common) and bare (ground)

[travelin texans]

Not to sound rude, but you don't have a volt meter or know how to use it, you don't know what Romex is or what operates on 12 or 120 volt, sounds like you need professional help before you get electrocuted.

[bsmith0404]

Originally Posted by travelin texans

Not to sound rude, but you don't have a volt meter or know how to use it, you don't know what Romex is or what operates on 12 or 120 volt, sounds like you need professional help before you get electrocuted.

That’s not being rude, that’s being truthful. I was thinking the same thing. If this was a 12v system, no big deal, but dealing with the 120v side…..different story

[wiredgeorge]

Danny makes an excellent point. The romex will be in a fairly heavy sheath and contain a white wire, a black wire and a green. The green is a ground and you test the black and white as Chuck noted but also if you purchase a less expensive meter, you will need to switch this meter to AC and the 200V scale in order to read the voltage. Placing your probes on the black wire with your red probe and white wire with the other probe you will should see the meter read about 120 Volts AC. If your scale is too low, the reading won't make sense.

I personally would check voltage at the power panel in a similar manner but I think perhaps this first series of steps above might be the easiest thing to do. I would also caution you that if none of the terminology makes sense, then do get a tech to check things as there is nothing wrong with your thermostat but more likely the power souce (AC) since you have had two air conditions not work in a similar manner.

Who installed the new Brisk A/C unit?