AC no workie!

[PT Doc]

Hi guys. I am always impressed with the wealth of experience that is part of the membership of gj. I need some help.

I turned on my Carrier ac unit on Sunday. Everything was purring along until this morning. I happened to be at the window I just opened and the furnace fan came on. Then I hear a buzz but the condenser never came on. I shut it off then the fan stopped. Then I lowered the temp and tried again and the same buzz. So it's been off all day. I tried after work and same thing. The fan moves very freely from the top.

I called the heating and cooling company and they will come in 13 days. Darn. She said it sounded like an electrical issue. This ac system is on its 3rd evaporative coil since they were leaking. The last was put in 2 years ago and I had them out last year to verify all was good and it was. When we had the problem in years past, it was signal for the condenser to come on and it would for a second then stop then try again. So I guess the symptom is different. A few years back the technician said that the electrical connection at the condenser had some dark marks that indicated something was arcing or had arced. Not sure about that and he said that could fail in the future.

Where would the condenser be located in the condenser unit? I have a multi meter and could check it if you guys felt this was doable. I'm not an electrician have wired lights, outlets, 240v line for compressor so I feel that with the right instruction I could try to test a few things. 13 days is going to kill me and my wife and little dog.

Thanks in advance for the help.

 

[Rockhead261]

A few years back the technician said that the electrical connection at the contactor had some dark marks that indicated something was arcing or had arced. Not sure about that and he said that could fail in the future.

FIFY.

Burnt contactors are not uncommon but are often symptoms of other problems. This is not a good DIY if you are not perfectly comfortable working with 240VAC; Let the tech handle it.

 

[PT Doc]

Unit has been running since 2004 so my guess is that there is not a big electrical issue. We are moving at the end of September so I want to pass on a strong working unit but 13 days won't out ac is just not great for me.

The ac has a cutoff outside, breaker in subpanel, so ensuring there is no power is very easy.

 

[zmaxmotorsports]

Start with checking the contactor for power on both sides,this is a picture of a typical contactor.
The can on the left side is the capacitor,be carefull with the capacitor.
The capacitor will store 370 or so volts evenafter power is off till its discharged.
The area under where the wires connect on top of the capacitor should be flat,if its bulged out you have a bad cap.

 

[rkevins]

turn the unit off with the t-stat then pull the disconnect at the back of the house, there should be a electrical panel on the back of the unit remove it and then reconnect power and turn back on at the t-stat look to see if contactor pulls in.

 

[Rockhead261]

Chances are you need a new contactor. Due to the age I'd also replace the run capacitor and check/replace all electrical connections, including the spade connectors at the compressor. Have the tech check the RLA on it - could be getting tight.

Don't kid yourself about it only being 11 years old; today's A/C units have dog lifespans. 15+ years is a great run.

 

[Alert5]

Sounds like your capacitor is bad. If you have a digital multimeter that checks capacitors you can disconnect the power going into the condenser then unplug the wires that go into the top of the capacitor. Take a screwdriver and ground out the fan terminal to the common terminal and the herm terminal to the common terminal that will discharge any charge in the capacitor. Most AC units have a dual capacitor that runs the fan and compressor that's why there are three terminals on top. If you look on the side of the capacitor you will see two different numbers like 45 microfareds and 7.5 microfareds and a voltage rating of 370 or 440. To check capacitor all wires disconnected from top of capacitor put common lead on common and positive lead on fan check to see if fan is reading the smaller number like 7.5 or what your capacitor is rated at and then swap positive lead over to the herm side and it should read the microfared of your capacitor. Capacitors are common failure especially when getting hotter outside. But if your compressor is humming outside and fan on top of unit is not spinning then it is probably the fan side of the capacitor.

 

[PT Doc]

thnaks for the replies. So much good info.

Alert5, that is an awesome first post. Welcome, this is a great community.

I will kill the disconnect and pull the side panel and post back with info and photos.

Thnanks again to all.

Is a new contactor a part that you get from the heating and cooling supply center or an industrial supply like Zoro? Thanks

 

[bczygan]

Can't help, but I feel for ya.

Just turned on my portable unit, and the fan makes a racket. Time to get out the tools.

 

[Jagmandave]

It's more likely to be the run cap, cheap fix. Just make sure you take a pic of the wires so you can put them on in the right order on the new one.


edit: oops, just read Alert5's post - spot on!

 

[LS6 Tommy]

Is it buzzing or just humming loudly? Buzzing could be a contactor, but if the condenser fan is running and the compressor is not, it's probably not that. Humming could be a stuck compressor, or hopefully just a bad compressor run cap. I don't want to sound overly negative, but if you've had recurring leaks, there is a chance you lost the charge and the compressor seized from lack of cooling. If the unit is a decent one, it will have a low pressure cut out switch to prevent that.

Tommy

 

[PT Doc]

Is it buzzing or just humming loudly? Buzzing could be a contactor, but if the condenser fan is running and the compressor is not, it's probably not that. Humming could be a stuck compressor, or hopefully just a bad compressor run cap. I don't want to sound overly negative, but if you've had recurring leaks, there is a chance you lost the charge and the compressor seized from lack of cooling. If the unit is a decent one, it will have a low pressure cut out switch to prevent that.

Tommy

It has a safety feature so that it won't run if you are low on refrigerant. We are on the third coil and everything tested fine last year. This is a different symptom as I described in the original post. I would describe the noise as a buzz. Fan does not run but is free to spin by hand.

Any guesses how much a contactor and capacitor would cost for a 5 ton carrier unit?

Thanks

 

[Jagmandave]

Look at the cap first, bad ones are usually noticeable....they're not very expensive....they're somewhere around $25, take the old one to the supply house and they'll fix you up......

 

[RPH]

Old school name for a capacitor is condenser. I think he was talking about the capacitor. Never have seen a " condenser" have an arc mark unless it was a capacitor. Check the caps or change them as the are cheap parts in the system and do die.

 

[brewchief]

Contactors often get bugs in them and will arc and damage the contacts, only way to know is to open the unit up and check both the contactor and capacitor.

To replace both parts DIY is probably 50$ or so in parts depending on source, we would charge close to 300$ to replace both.

 

[LS6 Tommy]

Don't short the capacitor. If it wasn't bad before you shorted it, there's a good chance it will be afterwards. Shorting a run cap can also cause it to heat up or even explode. Run capacitors almost never hold a charge as they're in parallel with the motor windings. They discharge when contactor opens. That being said, for safety reasons the run cap should be discharged. Proper cap discharging is done with a 20k ohm, 5w resistor installed across the terminals.

Tommy

 

[PT Doc]

Don't short the capacitor. If it wasn't bad before you shorted it, there's a good chance it will be afterwards. Shorting a run cap can also cause it to heat up or even explode. Run capacitors almost never hold a charge as they're in parallel with the motor windings. They discharge when contactor opens. That being said, for safety reasons the run cap should be discharged. Proper cap discharging is done with a 2k ohm, 5w resistor installed across the terminals.

Tommy

Radio shack has a 1/2 w 2k resistor. That is the biggest. Where are some logical places for something like this?

 

[WhiffySpark]

Supply house. Caps usually bulge when they go does yours look exploded?

 

[Rockhead261]

Radio shack has a 1/2 w 2k resistor. That is the biggest. Where are some logical places for something like this?

Not trying to be a **** at all, but please do yourself a favor and hire a tech. You can do some serious damage to the equipment or yourself if you're not sure what you're doing.

 

[PT Doc]

Not trying to be a **** at all, but please do yourself a favor and hire a tech. You can do some serious damage to the equipment or yourself if you're not sure what you're doing.

What are your thoughts about discharging the cap with the 2k ohm 5w resistor?

 

[WhiffySpark]

Look at the cap... Is it blown out?

 

[dadsEH]

Why wait 13 days....are they the only techs on the planet? I not like it's under warranty?

 

[PT Doc]

Pulled the panel and checked the contactor. It looks good, no charring.

The capacitor is swelled on the top, so it seems like a no brainier to replace it. Amazon has it for $25.00. The capacitor has 3 terminals as someone posted it would. Here is the writing on the label:

GE Capacitor
97F9816
60uf 5uf. 370VAC
+o6% -o6% 50/60hz
Protected P969
T10000AFC Dielktrol VI 0410
HC98JA061D H0013997
. 540

Since the capacitor looks be be toast, discharging with the typical screwdriver across the terminal should be ok?

If I get a new capacitor, and wire it up, does it get charged after I power up the unit?

Thanks for the help.

 

[PT Doc]

Why wait 13 days....are they the only techs on the planet? I not like it's under warranty?

Actually the last coil that was replaced is a 10 year warranty and if it is that then then using them makes sense. It has not been horribly hot in the house so we are likely to wait and see what the new capacitor does for the system. Since we are selling the house by summers end, I'd like to have then give the system a once over anyway. Thanks

 

[slice]

Screwdriver or needle nose pliers. Will discharge it. Replace like for like. Wire for wire. The cap is also labeled. H-C-F. It's easy to do. I assume you have home warranty and it will be -3 days for them to show up. What a crock. Order it. Pull disconnect on outside unit. Wire it in Turn it on. No need to charge it etc. replace turn on.

 

[PT Doc]

Screwdriver or needle nose pliers. Will discharge it. Replace like for like. Wire for wire. The cap is also labeled. H-C-F. It's easy to do. I assume you have home warranty and it will be -3 days for them to show up. What a crock. Order it. Pull disconnect on outside unit. Wire it in Turn it on. No need to charge it etc. replace turn on.

That is the quick and dirty. I watched a bunch of YouTube videos and there is nothing to it. Getting a capacitor on Monday and hopefully cool air blowing after I return from work.

I thank everyone for the information and also the warnings to be careful. Will post back when up and running.

 

[LS6 Tommy]

If the cap is marked "protected" it means there is a fusible link inside. Shorting it will almost definitely pop the link. It doesn't matter, you can pretty much be sure it's done if it's deformed or leaking. Probably discharged, too. Toss it. Put the new one in.

Tommy

 

[PT Doc]

If the cap is marked "protected" it means there is a fusible link inside. Shorting it will almost definitely pop the link. It doesn't matter, you can pretty much be sure it's done if it's deformed or leaking. Probably discharged, too. Toss it. Put the new one in.

Tommy

Tommy, thanks for the help. The fear and mystique of the ac unit has been cleared up with the posts here. I grew a pair and took the unit apart after killing the power and sure enough you were on the money. Thanks for the help.

 

[monkeyspanners]

If you've got a multimeter, just measure if there are and volts across the capacitor terminals it will discharge it as it measures if there is any, they normally discharge through the compressor and fan motor windings as soon as the power has been turned off, so unless the wires have become broken between the capacitor and motor there should be no power stored in it.

 

[zmaxmotorsports]

If you've got a multimeter, just measure if there are and volts across the capacitor terminals it will discharge it as it measures if there is any, they normally discharge through the compressor and fan motor windings as soon as the power has been turned off, so unless the wires have become broken between the capacitor and motor there should be no power stored in it.

Put your finger between the c and h or c and f on a cap after shutting the power off if you want.Personally Ill continue to short them out againt the condenser myself just to be safe.

 

[jade97]

Make sure you note the conductor markings. If you have space, move 1 terminal at a time from old to new. Use insulated pliers.

 

[monkeyspanners]

Put your finger between the c and h or c and f on a cap after shutting the power off if you want.Personally Ill continue to short them out againt the condenser myself just to be safe.

If thats what works for you. I made no mention of putting fingers on terminals, just advised that testing with a volt meter would show is the capacitor still held a charge and that if it did the charge would then be discharged through the multimeter.

 

[PT Doc]

Make sure you note the conductor markings. If you have space, move 1 terminal at a time from old to new. Use insulated pliers.

I took a good photo of the cap so I will call the HVAC supply shop and get a new one then swap wire for wire at the unit. Nothing to goof up that way.

 

[bonneyman]

The Chinese-made caps sold at supply stores are junk. If you get 2 years out of them you're lucky.
Get one of these - if they have them. Made in USA, tested to 10,000 volts, multi-tap terminal let you "make" the microfarad rating you need. It's all I use anymore.
If your problem is a bad cap, this is the part to go with.

http://www.americanradionic.com/

 

[Mike007]

The Chinese-made caps sold at supply stores are junk. If you get 2 years out of them you're lucky.

You can say that again. If I replace a motor or compressor and the old cap is the correct uf, I don't replace them anymore. New China caps are pure $hit.

 

[PT Doc]

The Chinese-made caps sold at supply stores are junk. If you get 2 years out of them you're lucky.
Get one of these - if they have them. Made in USA, tested to 10,000 volts, multi-tap terminal let you "make" the microfarad rating you need. It's all I use anymore.
If your problem is a bad cap, this is the part to go with.

http://www.americanradionic.com/

You can say that again. If I replace a motor or compressor and the old cap is the correct uf, I don't replace them anymore. New China caps are pure $hit.

Good to know. I'll try to get a non chinese cap. The GE unit that was in my Carrier unit lasted 11 years and in was made in Mexico, so I would not hesitate to get another GE unit.

 

[Falcon67]

>The Chinese-made caps sold at supply stores are junk. If you get 2 years out of them you're lucky.

One year, maybe. This was the third year for a cap fail - this time we spent $7000 to replace the cap. That should hold it for a while.

 

[zmaxmotorsports]

If thats what works for you. I made no mention of putting fingers on terminals, just advised that testing with a volt meter would show is the capacitor still held a charge and that if it did the charge would then be discharged through the multimeter.

I was going by your post about the cap discharging itself when the power is turned off is all.

 

[jade97]

Chances are...if the cap is bad, it won't be holding a charge. Just don't touch the terminals.

 

[PT Doc]

wife bought new cap that came from carrier for $31. Will swap it out tonight and hopefully she gets a purrin.