Trane A/C Unit XB1000 circa 6-2000

[papollonia]

Hey Guys:

Unit Specs:

Trane XB 1000 Date: 6-2000

Mod # TTB030C100A1

Ser #  R273U71BF

I went to test the a/c system the other day..

Powered it on, as i was walking up to the unit I heard this Tinging sound about every second or two..

It was coming from behind the cover.

Took the cover off, and turned it back on and the relay on the right in the photo was sparking (very Bright)..at the top of the relay..

Is it a bad relay or something else?

It does not look that hard to replace?

Any advice.

Thanks in advance...

 

[hvacdrd]

It should be an easy replacement. It is a contactor 1-1/2 pole, 24vac coil, likely rated for 30 amps. You should be able to find one at an electric motor shop or HVAC supplier. I'll see what I can find online...

[papollonia]

YOU GUYS RULE!!!!!!!!!

Thanks

[hvacdrd]

Something like this...94-388 or 60025. The amp rating and coil voltage should be listed on the old one.

When you install the new one leave power off to the condensing unit, turn down the thermostat and verify that the contactor pulls in without chattering. If it is then you will need to find out where you are losing the 24VAC to the coil before applying power to the condenser.

[applianceman18007260692]

That is a single pole, 30 amp, 24 volt contactor.

Pretty generic. It is called a 1.5 because it has a common pole that runs straight through on one side. From what you prescribe that is what we call chattering in the biz.Probably going bad. Replacement imminent.

[papollonia]

Update:

I got it off today, will get the replacement and install edwithin the next few days..

Thanks guys...

[papollonia]

Ok, I installed it today.

Put the fuse pack in the wall.

Cut the power on.

Turned the t-stat down to 60 degrees.

The only thing that happens is the fan clicks ( spins ) for a half a second..

I pulled the fuse out and back in to verify that is what happening.

Had my 8 year old girl out there, so I wanted to make sure she was correct!!

better her then my 11 year old boy!!! love him but!!!

My uneducated guess is:

Maybe a Start Cap. (is that the one that controls the fan? )

Thanks

[papollonia]

Any ideas Guys??

Thanks

[hvacdrd]

With the fuse removed is the contactor pulling in? From the posted picture the capacitor "looks" ok but can't be sure without testing. Do you have a volt/ohm meter and know how to use it?

[papollonia]

Ooops,, you did ask me to do that sorry.. Will do that test either Thursday or Friday

Yes I do have volt/ohm meter.

It been like 20 year since i used one on a regular basis. So I think I can remember  know how to use it?

[Bobice]

Okay, first the purpose of the 1.5 pole set up is it maintains trace voltage to the compressor during the off cycle. This is to keep the compressor oil warm rather then usig a crankcase heater.

Second, you cannot tell the condition of anything just looking.

Third, using VOM to test capacitor : 1. Turn power off at disconnect 2. Set meter to ohms (8 on side) 3. This is a dual capacitor (HERM,C,Fan) so place BLACK lead on C and touch RED lead to HERM ( needle or numbers should move up, then slowly down). 4. Due the same for Fan terminal. BTW how's the heater ?

[papollonia]

" When you install the new one leave power off to the condensing unit, turn down the thermostat and verify that the contactor pulls in without chattering. If it is then you will need to find out where you are losing the 24VAC to the coil before applying power to the condenser. "

Yes the contactor pulls in..

Now I will test the Cap has Bobice's advice.... 

[papollonia]

BTW how's the heater ?

I guess I never kept my promise of getting to it last week

Let me get this upstairs A/C going so the Wife and Kids are happy, then I will get to it..

[papollonia]

BTW how's the heater ?

I guess I never kept my promise of getting to it last week

Let me get this upstairs A/C going so the Wife and Kids are happy, then I will get to it..

[Bobice]

On most single-phase compressors with a single-pole contactor, there is a solid bar on one side of the contactor instead of having two contacts. One leg of power passes down the bar to the capacitor and to the run winding. It passes through the run winding of the compressor and from common back to the contactor. It lands on the load side of the normally open contact of the contactor. At off cycle, line voltage will be read from one side of the normally open contact to the other: Line 1 on the line side and Line 2 on the load side via the windings.]

[papollonia]

" using VOM to test capacitor : 1. Turn power off at disconnect 2. Set meter to ohms (8 on side) 3. This is a dual capacitor (HERM,C,Fan) so place BLACK lead on C and touch RED lead to HERM ( needle or numbers should move up, then slowly down). 4. Due the same for Fan terminal. "

Ok I am sitting at the table with the Capacitor and my VOM..

Set to Ohms..

Place Black lead to 'C' the red one to ' Herm ' Nothing happens....

Place Black lead to ' C ' the red Lead to ' Fan ' Nothing Happens...

By ' Nothing Happens ' I mean the VOM just sits at ' 1 '..

SO does that mean it is bad?

Or am I doing something wrong?

[Bobice]

If no movement, replace.

[papollonia]

Cool !!!!!!!!!!!!!

Will get one Monday... and put in 4 months from now LOL... Just like the heater.. Right..

[Bobice]

You are learning valubale lessons "Grasshopper". :)

[RegUS_PatOff]

[user=42812]papollonia[/user] wrote:

... By ' Nothing Happens ' I mean the VOM just sits at ' 1 '..

SO does that mean it is bad?

Or am I doing something wrong?

If using a digital meter, depending on the model, it won't respond on the lower (200 Ω & 2000 Ω ) scales...

Try the 20k Ω scale, then reverse the leads and re-read...

[papollonia]

[user=3641]RegUS_PatOff[/user]:

Thanks,,, It is a digital meter.  I did try all the setting,, and nothing..

Thanks anyway

[papollonia]

Ok:

I replaced the Cap.. and it runs, cools very nicely!!!

Then I noticed that when the t-stat reaches the proper temp. the unit never really goes off.. Meaning, it is trying to stay on, It runs for a second and goes off and the same over and over again...

I pulled the fuse...

[papollonia]

Oh My!! I never gave you an update !!!!

Everything was fine after the install of the Cap... then this morning The a/c was not turning off so I replaced the t-stat.

Now everything is fine.

Bobice: now I will look at that heater again !!!!!!

Thanks for all you help guys