Typing on my phone, sorry if it is a bit choppy. A/C fan was working but not cooling. Flipped the breaker and started taking off the grille to clean the unit. There was a spark, that I did not see the source of, but it seemed to come from inside the unit by the compressor. If I had to guess it seemed to come from the pressure switch. Turns out the installer or someone bypassed the breaker and it still had 240v power. Didn't have multimeter to double check it. Anyway, got the grille off and cleaned the fins out and reassembled the unit. Turned the power back on and turned on the a/c and nothing. Now nothing worked including the fan, except a small buzzing from the unit.

Decided to just replace the capacitor and contactor rather than test them. Did so and powered up the unit, and nothing again. Contactor is engaging (small buzz) but that is it. Fan spins freely. There is no reset on the pressure switch, just the switch and two wires.

Indoor unit working fine.

Is this a pressure switch that needs to be replaced? Any ideas?

It is a York, with dual capacitor.

Model: tcgd36s41s3a

Thanks!!

 

Do you have 240 volts present now?

Do you have a square d breaker type disconnect?



I always dread turning off that disconnect since it often fails when it is over 5 years old.

 

The box is there but no disconnect. It's hard wired. I have cut the power to the unit now, and got a multimeter to confirm.

I did forget to mention that the unit is 7 years old.

 

Not having a disconnect is an accident waiting to happen. The disconnect is there to guarantee no power to the condensor while servicing it. Replace it.


and....................

 

Not sure what you are asking, my appologies.

I can confirm that there is currently no power going to the unit.

 

You made measurements and didn't say what they were.

Where did you check at the condensor ?
You had cut power.... did you restore it to check ?

If there is no 240vac at the condensor then you need to check at the breaker in the main panel where the circuit originates.

 

Ah. Ok so I haven't checked at the condenser, to be honest I am not sure where or how would be appropriate for the condenser.

I have checked at the contactor and am getting 240 in 0 out.

I did restore power to check. Getting the same numbers, and the same no fan or compressor after replacing contactor and capacitor.

I will put in a disconnect, but at this point I am trying to get the unit operational. The builders did some hack jobs on this house and I have been fixing them one at a time since we moved in.

 

So.... you're telling us that you replaced the contactor. You have checked and found 240vac going into the contactor. The contactor is closing and humming. Nothing is coming out of the contactor.

You've missed something there.

 

 

Sorry.

With a/c call off from thermostat 240 in (L1 and L2) and 0 out (T1 and T2).

Call on from thermo 240 in and 240 out.

 

If I am getting 240VAC in and out of the contactor and nothing runs, I would expect to find the compressor out on thermal protection and very hot, I would also expect a fan motor failure.

Do you know how to measure the motor for open windings?

 

No I don't know how to check windings. Maybe I can find a tutorial on YouTube.

 

Ok, so if I did this incorrectly forgive my ignorance.

I cut the fan motor wires and did an ohm check. Here's what I got:

Brown to black: 51.4
Brown to red: ol
Black to red: ol

I am guessing that is a bad fan motor. Strange since it was working before I cleaned the unit.

Also, not sure if this is even a correct test, but since it is getting dark I did it anyway.

I cut the wires to the pressure switch and did the same ohm test.

I got .4 on that one.

I am not sure if that helps or if I did those right but there you go.

Thanks everyone for all of your help.

 

You only got common to start.

You have a broken or open run winding.

If the motor isn't hot to the touch when this measurement was taken then you need a new motor.

The new motor may require a different size run cap so I would check when ordering it.

 

Really? So weird. So are fans universal or model specific? When I search condenser fans I see the for $60-$70, but when searching by brand or model number it's $122-$180.

 

Did you confirm that the compressor was also very hot ?
It should have been trying to start while you were testing.

You can get a universal motor but it's more leg work on your part. It may require the shaft to be cut. Sometimes the mounting bolts need to be cut. You will have to match specs item for item.

 

I don't think the compressor was hot. I will check again tomorrow to be sure.

 

Now that everything has cooled off. When you call for A/C the contactor will close and the compressor should start. It won't (and shouldn't be) run long without the fan also running.

 

It wasnt easy to tell as I don't have time to turn the unit on and run outside, so I used a window to listen, but I didn't notice the compressor come on.

 

There is usually a 5 minute delay time built into the thermostat or the condensor.

 

Did a continuity check on the compressor and got a tone across all of the leads.

 

So do I hook everything back up, flip the breaker on, and turn the thermo to cool and wait 5 min? The contactor is on right away, but is that not on the same delay?

Man I am a rookie with hvac's sorry.

 

The 5 minute delay that Pete mentioned would be from when the A/C calls for cooling until the contactor is energized. If you're seeing the contactor pull down, then the 5 minute delay doesn't apply. Actually, usually the delay is to prevent the A/C from turning on too soon after it shut off. I wouldn't expect the 5 minute delay to come into play unless the thermostat had been calling for cooling, turned off, and then turned back on again.

 

Ok so I am not sure where I am at then. Is it the fan?

I have replaced the contactor and capacitor. I get continuity across the compressor leads. The breakers are good. The thermostat is good. The blower is on indoors.

I don't know hvacs but I would think that would leave:

1 fan motor (which is weird since it was working, unless that spark had to do with the motor.)

2 pressure switch? (No reset switch, so not sure how to check.)

3 coolant level? (Shouldn't the fan and compressor still come on?)

Is there anything else it might be? We are roasting and kids are getting chewed by mosquitoes. Would really like to fix this.

Thanks so much everyone for your help.

 

This has become a very long thread. Let me try to summarize and let me know if I got something wrong.

1) You were working on the unit and the power was unknowingly still turned on. You touched something and saw a spark.

2) You have replaced the contactor and capacitor.

3) You have confirmed that you have 240VAC at the input to the contactor. Is there 240VAC at the output of the contactor when the thermostat is calling for cooling?

4) You cut the wires going to the condenser fan and measured with an ohmmeter. You get 51 ohms from Brown to Black, no resistance (infinity) between all other combinations. If the motor was cold when the resistance was measured, I suspect that the fan motor is bad, possibly burned out when you saw the "spark".

5) You did a continuity check on the 3 compressor terminals and measured continuity between all combinations of terminals (1-2, 1-3, 2-3).

I the above summary is correct, I would go outside and watch the contactor. Have your wife turn the thermostat to cooling and see if the contactor terminals pull in. If they do, take your voltmeter and check that you have 240VAC at the output of the contactor. (T1-T2). If the contactor isn't pulling in when the thermostat calls for cooling, use an insulated tool (wood or plastic) and carefully push the movable portion of the contactor in so that the contactor is enabled. Does the compressor now run?

 

If the contactor closes..... then the pressure switch and refrigerant charge is ok.

I think I see the problem.... in the picture of the cap....
I see what looks like a brown, brown/white and red wires.
If what I posted is correct the capacitor may be wired wrong.

Brown and brown/white from the fan don't get connected to a dual capacitor.
At least brown/white doesn't on a 4 wire fan.
I believe your are missing the supply to the cap.

Is that the only cap in the system ?

 

The cap is wired with those colors.

Red goes from c to contactor
Brown goes from herm to compressor
Brown/white goes from fan to fan motor

The fan motor wiring has a quick connect connector on the harness. The brown wire from the fan turns into a brown white on the capacitor side of the quick connect, so that be the confusion on that one.

 

Hey Bob, sorry about the length of this thing.

1. Correct
2. Correct, both are new.
3. 240v input 240v out put with call on.
4. That is correct and fan was cool during test.
5. Correct.

I am at the house alone right now, but I did make sure contactor was out and checked with meter 240 in 0 out. Manually depressed the contactor and sounded like compressor was on. Then went inside and turned on the thermo to cool and made a dash outside. The contactor was in and meter read 240 in 240 out, and compressor on.

Left unit on for a while and it didn't seem like the compressor was turning off, so I turned unit off at thermo and contactor released.

 

OK... just to comment on your testing. All sounds good there. Compressor running is a major plus at this point. If the fan wasn't running.... the compressor would run until it overheated.



I realize the fan motor is open.... damaged.... but what color wires are on it ?

Usually red, black, brown, and brown/white or black, white, brown and brown/white.
If it's a four wire motor.... brown from the fan goes to the cap and brown/white gets capped off.

 

Red, black, brown, and green. Green being ground I assume.

 

upload pic for free

 

Ok... in that case the brown/white does go where it is on the cap.
That is considered a three wire motor. The green is ground but not counted in wiring count.

It looks like at this point you need to replace the fan motor.

 

The solid brown turns into brown white after the quick connect on the fan wiring harness. I think that might be the confusion.

 

Sorry for the delayed response. I was waiting for the 180 seconds and you posted in between.

New motor it is! Thank you guys so much for your assistance. It is truly appreciated! I will let you guys know if the new motor fixes it. Thanks so much!

 

New motor and the unit is running, but still no cold air. At this point I am guessing it needs to be charged?

Might it be something else?

If it does need a charge is that a diy? I have used Gage's and a vacuum pump on auto a/c before but not a home system?

Thanks again

 

We follow logical steps when we troubleshoot.

IF the fan is running..... then it sound like the contactor is closing.
If the contactor is closing then your pressure switch is closed which means you have enough refrigerant.

You confirmed the compressor was running..... is it still running ?
If you can't tell..... disconnect the fan wiring and listen then.

A car's A/C system uses different refrigerant and gauges.
Anyone can buy and put in auto refrigerant.
Only an EPA licensed tech can charge a home A/C system.

 

It sounds as though it is running. Then again I suppose I could just be hearing the Contactor. It Hums louder than I expected.

I thought you had to be EPA cert for auto a/c discharge, vacuum and recharge too. Though when I replaced the engine, I just did it myself.

 

The contactor can't be noisier than the compressor.

Turn the thermostat off, leave the fan disconnected, now press in the contactor with a non metallic item. Is the compressor running or not ?

 

I can't get to it until tomorrow or Monday, but if I remember the louder noise was coming from the contactor, so perhaps the compressor is not coming on after all.

 

The contactor shouldn't make any noise other than a click when it turns on or off. It's merely a relay.