Condenser issues

[Trugger72]

I'm a recent graduate of ETI hvac school and am trying to fix a condenser. So far I have replaced the capacitor, contactor, and circuit breaker, added a hard start for the compressor, and checked all the wiring at the condenser. As of now, when I turn on the circuit breaker I hear a noise coming from the conduit for a moment and it trips. The condenser doesn't even start. I'm about to change out the wire going from the circuit breaker to the disconnect. Was just wondering if there is anything else that I could be missing if this doesn't work, aside from the condenser needs to be replaced.

[jtrammel]

No DIY read the rules. Get your post count up and apply for pro status

[jtrammel]

Don't turn the breaker on again you could start a fire

[beenthere]

Moved to Tech to Tech Residential.


Your throwing parts at it. Go back over your books. call a friend from school, or your instructor.

[qwerty hvac]

Use the basic skills that you just learned. Ohm out your components and you will find your issue.


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[ironpit]

Water hammer? :D

[OldSchoolMech]

How much was school and you sure it was HVAC you learned?
Do you own a multimeter? USE IT! Or Sell em a new unit. So they get some cooling

[jpsmith1cm]

ETI?

Are you in NE Ohio?

[2sac]

I'm a recent graduate of ETI hvac school and am trying to fix a condenser. So far I have replaced the capacitor, contactor, and circuit breaker, added a hard start for the compressor, and checked all the wiring at the condenser. As of now, when I turn on the circuit breaker I hear a noise coming from the conduit for a moment and it trips. The condenser doesn't even start. I'm about to change out the wire going from the circuit breaker to the disconnect. Was just wondering if there is anything else that I could be missing if this doesn't work, aside from the condenser needs to be replaced.

LOL A trainwreck in the making.

[mark beiser]

That's a lot of parts to throw at a bad compressor...

Good thing it isn't a 480v system in a commercial area. With the problem that is most likely causing the breaker to trip, repeatedly attempting to reset it could result in an arc flash explosion, resulting in serious injury or death to you and anyone nearby.

[BigBacardi]

im thinking the flux capacitor is upside down. also Ltry changing wires from L1 and L2 to each iother side of contractor.reverse phase is always a possibllity in the fall

[AYservicetech]

Dont be a parts changer..... No offence but you obviously arent experienced enough to do service yet... Its okay to be eager to learn but you have to know your capabilities...... Change some filters and Carry someones tools for a while and pick their brain until you have a good understanding of the equipment you're working on... Otherwise u'll just be costing someone alot of money.... ull get there

Also, i wouldnt recommend another post like this one... Ur setting yourself up for some of the guys on this site to chew u up

[timebuilder]

I agree, in that a meter can be used to find the problem with the power off, and also used to avoid all those parts getting replaced.

Get your post count up to 15 and apply for Pro membership. As a Pro, you will get a better reception, more help, and less critique of your approach.

Truthfully, they should have equipped you with the knowledge to do this diagnostic. But, this trade IS a continuous learning experience, and this is how you learn....

[nismo1]

Get pro status and I'll tell u how to fix it!!! Lots of pros here. You're in that sticky spot between school and experience. Great info in the pros forums. Never mind the taunters they used to bd u.

[AYservicetech]

And dont waste your time replacing the wire.. It isnt going to help..... Get a qualified pro to check amps and ohm out cond fan and compressor.. One of those two is the problem

[hvaclu420]

And dont waste your time replacing the wire.. It isnt going to help..... Get a qualified pro to check amps and ohm out cond fan and compressor.. One of those two is the problem
Glad to see your response is trying to help the guy out in a nice way

[newoldtech]

This thread has already been deemed as either DIY or not appropriate for an open forum, so why doesn't it just get closed? There is still alot of DIY tips being exchanged in threads like this. Once its been found to be inappropriate for the open forums why is it not just shut? Threads like this IMO will turn this site slowly but surely DIY. The main reason I've always liked HTALK is it wasn't a DIY site, I hope it stays true to that mission.

[jackintheboxtec]

My suggestion is to go back to ETI and demand your money back... :gah:

[beenthere]

My suggestion is to go back to ETI and demand your money back... :gah:

I doubt many schools teach a good diagnostic procedure.

And the equipment in a school, seldom looks like it does in the real field.

[jackintheboxtec]

I'm pretty sure they teach you how to test a compressors windings.

A compressor looks like a compressor in any piece of equipment.

[beenthere]

I'm pretty sure they teach you how to test a compressors windings.

A compressor looks like a compressor in any piece of equipment.

It was probably in more then one book he read.

[Newtech72]

Dead short somewhere.

[jpsmith1cm]

I doubt many schools teach a good diagnostic procedure.

And the equipment in a school, seldom looks like it does in the real field.

HERE is the real problem.

Schools teach theory and, while I believe that a solid foundation in theory is a mandatory part of this trade, they don't teach things like how to approach troubleshooting in a logical and systematic method.

Just keep cranking out graduates with a loose foundation in theory and no foundation in troubleshooting.

[Shophound]

HERE is the real problem.

Schools teach theory and, while I believe that a solid foundation in theory is a mandatory part of this trade, they don't teach things like how to approach troubleshooting in a logical and systematic method.

Just keep cranking out graduates with a loose foundation in theory and no foundation in troubleshooting.

Troubleshooting and a solid grounding in theory go hand in hand.

That said, I agree more effort can be applied toward teaching practical applications of theory.

In the OP's case, the first thing he should learn is how his parts changing efforts are leading to a dead end. "Oh, I think it's this"...changes that and same bad result. Right here is where he needs to stop and think "This way of trying to figure out what's wrong is not working for me!" IOW do I keep swapping parts until I get lucky, or do I dig up theory and put it to practical use? The latter is direct short = tripped breaker, referring to basic electrical theory that all electrical circuits require a load to operate safely. Find where the direct short is and there will be no need to keep changing parts hoping to get lucky.

[KtRoP]

Hey everyone, this post was created by a buddy of mine from school that I went by and tried to help him figure out what was wrong with his parents A/C. I myself am an install helper and have been for about 4 1/2 months now so I don't have much troubleshooting experience, other than what I was taught at trade school.
THe first thing we check when I get there is if there is power at the contactor and there wasn't. Then moved to check for voltage at the disconnect and still nothing. So we go down and check the breaker and it is still in the ON position but I decide to reset it anyway. Go back outside and there is 235 volts at the disconnect. From there we decide to replace the 40amp breaker, since is was not in the tripped position although it was tripped, and replace it with a 50amp breaker which is the max allowed according to the condensed nameplate. I take a closer look at the contactor to realize that 1 of the load side terminals is fried and the wire that was connected to it was loose. So now we need to replace the contactor. Take a look at the run & start caps and see that they are completely rusted, probably originals from 20 yrs ago, so decide to replace those as well as preventative maintenance more than anything. At this point we are thinking that since the unit is 20 yrs old that the compressor is probably to culprit and is drawing too many amps on start-up and tripping the breaker which is why we decide to go with a 50 amp breaker and also pick up a Hard Start kit just in case we need it as the supply houses were closing in 30 minutes. We get back and install the new contactor, caps, breaker and hard start kit, flip on the breaker and it immediately trips. No keep in mind that there is NO call for cooling and the coil is not energized. So we are thinking it is an electrical problem somewhere in between the contactor and the panel, possibly a short. So we check for continuity from the contactor to the disconnect, good. We then check from the disconnect to the panel, good. The disconnect did not have a ground running to it, which from what i recall is not necessary anyway as the coinduit acts as a ground, but we decided to run one anyway because with every new install we do, we run a ground. So being that it was only a 10' run we decide to just replace the wiring from the panel to the disconnect as even though there was continuity through them, they did not look all the great. We replace the wiring and add a ground, flip the breaker and again immediately trips. From here we take the wires off the contactor and wire nut them to check if the disconnect is good. Flip the breaker and it stays on. We reconnect the wires to the contactor and pull all wires off the load side of the contactor and flip the breaker, it stays on. Now this is where i got confused because there is no call for cooling and we just checked everything there is from the contactor to the breaker and all were found to be good... So I reconnect all leads back except for 1 of the compressor leads and flip the breaker on and it stays on but the cond fan kicks on as well. Being that there is no call for cooling and the coil is not energized I come to the conclusion that the supply house gave us the wrong contactor, even after bringing the old one to them and asking for the same type. Now I am going back to the supply house on Tues to swap the contactor, which I believe is what our problem is at least for now, and see if we can get the unit running. It wasn't until after we had left that we realized that we could have checked megohms on the comp to test if it was good, but then that still wouldn't have anything to do with the fan kicking on with no call.
This may be an obvious problem to you more seasoned/experienced techs but we would appreciate any advise on what we could have done differently to solve this problem and also if there is any other possible reason why the fan would kick on with no call for cooling.
Thanks in advance for any help and sorry for the lengthy message, just wanted to explain the whole situation and our thought process.

[jpsmith1cm]

First, I'd like to second the suggestion of Professional Membership to both of you.

Items like this are only discussed in so much detail in open forums.

Do either of you own an ohm meter?

[timebuilder]

I'll echo what JP just said. We don't dissect these things in open forums.

NEITHER of you should be doing this kind of diag without an experienced guy standing right there. You spent a bunch of time and money on parts, and neither of you had the first clue of what should be done, nor in which order.

That's not a slam against you guys, but it is something you need to understand. We can't walk you through the steps, and you need to do a better job of communication. If you can polish up that one skill, you will be able to talk on the phone to your service manager in the future, and then he can help you get to the bottom of an issue you have in front of you.

For us, a clear picture of the situation is needed. Ideas are separated into paragraphs. You mentioned upsizing a breaker. Was it in the outdoor disconnect, the service panel, or someplace else? We can't see, you must create the images in our minds, by using YOUR words.

You paint the picture, we respond with our own word pictures in reply.

So, for right now, let's set this aside, and you two get ready to apply for the free Pro membership, and then, in a closed forum, we can begin to teach you a little about diagnostics.

[KtRoP]

Sorry, I will get my post count up and apply for Pro Membership.
We have the Fieldpiece SC56 which does measure Ohms.

[qwerty hvac]

Yeah guys apply for pro membership and we will be more then happy to help you out.


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[david912]

Use the basic skills that you just learned. Ohm out your components and you will find your issue

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using Tapatalk

:ditto:

[jpsmith1cm]

Sorry, I will get my post count up and apply for Pro Membership.
We have the Fieldpiece SC56 which does measure Ohms.


Perhaps you guys should study up a bit on using that to diagnose a bad compressor, bad capacitor and bad fan motor.

The basic processes should be in your books from school.

[mark beiser]

I won't go into much detail in this open forum, but from the breaker tripping with all wires connected, but no call for cooling, and the fan motor running when one of the compressor wires is disconnected, there are 2 things that are highly likely.

1) The compressor windings are shorted to ground.
2) The unit has a single pole contactor.(only one side is switched)

The fan motor would only be running around half speed because it is operating off 120v instead of 240v, and will eventually turn off on thermal overload.
Don't touch any unit you walk up on that has a fan motor turning at less than full speed, and a compressor that is not running. There entire unit will be electrically "hot", and touching it can/will get you shocked if you are grounded.

[pcp]

Sound like your closer to starting a fire than fixing an ac. Just because the name plate says you can use a 50 amp breaker doesn't mean the electricians ran wire for it.
I had two units this summer that tripped the breaker immediatley with no call for cooling. I didn't replace any parts or wiring to get them running. They both happened to be trane units.

[ryan1088]

HERE is the real problem.

Schools teach theory and, while I believe that a solid foundation in theory is a mandatory part of this trade, they don't teach things like how to approach troubleshooting in a logical and systematic method.

Just keep cranking out graduates with a loose foundation in theory and no foundation in troubleshooting.

I agree completely. For the past few months I have had a recent tech school grad riding with me. Since he has been with me he has learned the procedures to troubleshoot which they obviously don't get in school. Unfortunately it costs the business owner and customer alike. That was one criticism I made in our review of the school in a report my boss and I wrote. I'm trying to get everyone to agree to let me to talk to the next prospective class of people entering this coop program to try to deal with some of that.

[mark beiser]

Just because the name plate says you can use a 50 amp breaker doesn't mean the electricians ran wire for it.

As long as the wire is sized for the minimum circuit ampacity of the unit, and the units name plate calls for a max fuse/breaker size of 50A, a 50A breaker is what should be installed.

Many people incorrectly use the NEC rules for general wiring when sizing wiring and breakers for AC units, when they should be using the rules in NEC article 440, which are a bit different.

[ryan1088]

That's a lot of parts to throw at a bad compressor...

Good thing it isn't a 480v system in a commercial area. With the problem that is most likely causing the breaker to trip, repeatedly attempting to reset it could result in an arc flash explosion, resulting in serious injury or death to you and anyone nearby.

It scares me too that there was no mention of arc flashes or any training given in school. The first time it came up, I have my guy the class basically. He then went to watch some videos on YouTube about it. I'm surprised he came back in after seeing all of that, I know I almost didn't.

[pcp]

They replaced a 40 amp with a 50amp breaker

[KtRoP]

It was a 10' run with 8awg wire from the breaker panel to the disconnect.

I know that with the capacitors you check mf, which we did and saw that they were within tolerances, but we replaced anyway because of the condition of them. They were completely rusted.

We did not ohm out the fan motor or the compressor. I admit that we did learn that in school but not having been on the service side of the industry, I forgot to check that. Also, the fact that it was tripping with no call for cooling is another reason I did not think of checking the windings because I didn't think it was getting to that point.
I will go back into my books and read up on how to check for a grounded. All I remember is that you check using ΜΩ and I believe you check across all terminals. I also recall checking from each terminal to ground individually but don't recall what the readings should be.
Thank you for all the advise.

[Rob_in_WV]

My best advice for this time is to use it as a learning experience and work on your troubleshooting process. I have a routine that I follow for every service call and the results of that will lead me to what needs to happen next. Advice for the future, ask for help sooner! there's no shame in asking for help, I know I've done it many times and will do so again many times. Above all else get the pro status and you will see a level of knowledge out of guys like JP, qwerty, Ryan and time builder to name a few that honestly many people don't even know existed, but they got lots of good stuff locked away in those brains that they will share in a closed forum.

[timebuilder]

My advice is to find a guy that you know has this work down to a science, and ask him to come and look at the unit in question. You and your friend explain your student status, and ask him to show you what SHOULD have been done.

I guarantee that if you can make that happen, several lights will turn on in your heads.

[kamersoutdoor]

30amp = 10awg
40amp = 8awg
50amp = 6awg
60amp = 4awg
Always protect your wire by properly sizing breakers/fuses.

sent from my Samsung Galaxy Note

[beenthere]

30amp = 10awg
40amp = 8awg
50amp = 6awg
60amp = 4awg
Always protect your wire by properly sizing breakers/fuses.

sent from my Samsung Galaxy Note

NEC allows larger breakers for motor only loads.

[kamersoutdoor]

NEC allows larger breakers for motor only loads.

Would this apply to condensers/compressors?

sent from my Samsung Galaxy Note

[beenthere]

Would this apply to condensers/compressors?

sent from my Samsung Galaxy Note


Yes, as long as its a motor only load, it applies.

[timebuilder]

30amp = 10awg
40amp = 8awg
50amp = 6awg
60amp = 4awg
Always protect your wire by properly sizing breakers/fuses.

sent from my Samsung Galaxy Note

First of all, no one can use such a list to determine ampacity of conductors OR selection of overcurrent devices. That requires Article 310.

Exceptions:

Motors and motor controllers are Article 430.

HVAC is Article 440.

HAVC conductor sizing is not, repeat, NOT the same as sizing for general use circuits. HVAC conductors are protected by the internal overload devices inherent in the design of motors and compressors.

The overcurrent devices used for a HVAC branch circuit are for ground fault and short circuit protection, and NOT overcurrent protection of the conductors. These overcurrent devices are sized according to the maximum overcurrent device value (if listed) which is 125% of RLA for the unit.

If you are in our trade, you should have a copy of the NEC, tabbed and ready for reference, in every truck.

[timebuilder]

Breakers for motor compressors that do not use a motor starter (which is most of the stuff we install and service) can be oversized up to 225% in extreme circumstances, as needed, to prevent the overcurrent device from opening during starting current events. Normally, the upper limit is 175%, when the 125% value is not sufficient to prevent tripping during starting.

Everyone should become familiar with this set of articles.

[mark beiser]

30amp = 10awg
40amp = 8awg
50amp = 6awg
60amp = 4awg
Always protect your wire by properly sizing breakers/fuses.

sent from my Samsung Galaxy Note


Would this apply to condensers/compressors?

Look up NEC article 440, in most cases involving condensers, it is completely ok to install a breaker that is larger than what would normally be allowed under 220.

[timebuilder]

Article 220 is branch circuit, service, and feeder calculations. It is used for load calculations and demand factors.

Article 310.16 (2008 edition) and 310.15 (B)(16) in the 2011 edition are for conductor sizing. This is for general requirements.

The other articles have their OWN specifications for ampacities and protection based on the type of use.

[jpsmith1cm]

My best advice for this time is to use it as a learning experience and work on your troubleshooting process. I have a routine that I follow for every service call and the results of that will lead me to what needs to happen next. Advice for the future, ask for help sooner! there's no shame in asking for help, I know I've done it many times and will do so again many times. Above all else get the pro status and you will see a level of knowledge out of guys like JP, qwerty, Ryan and time builder to name a few that honestly many people don't even know existed, but they got lots of good stuff locked away in those brains that they will share in a closed forum.

Thanks for the props, Rob.

I agree that there are a TON of smart dudes on here and most of them tend to spend more time in the Pro forums.

Now, I don't know if it is a franchise type school, but ETI Tech school is only a few miles from me. I drive past it on a regular basis and we've hired their graduates.

I've already got an apprentice and a few guys who call/text/e-mail me for advice, but I'd be willing to provide a wee bit of advice under the right circumstances.

[kamersoutdoor]

Very good info!
But I also see no harm in playing safe when in doubt?

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[beenthere]

Very good info!
But I also see no harm in playing safe when in doubt?

sent from my Samsung Galaxy Note


Jut follow the NEC.

[timebuilder]

Very good info!
But I also see no harm in playing safe when in doubt?

sent from my Samsung Galaxy Note

When you understand the requirements of the NEC, there IS no doubt. Now, if you want to raise your ticket amount by upsizing conductors, yes, you can do that. But it's not a matter of safety.

If you get into a competitive bidding situation, knowing the requirements can save you money, and lower your bid price, while still maintaining safety. Then, it is a win.

[kamersoutdoor]

Jut follow the NEC.

Am I being told that I do not have to run #8 out to disconnect with 40amp breaker? Or are we talking about load side (after disconnect)?

I always try to follow code, and throughout my time have never been questioned on sizing line side wiring. I just think liability, and it scares the crap out of me!



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[kamersoutdoor]

When you understand the requirements of the NEC, there IS no doubt. Now, if you want to raise your ticket amount by upsizing conductors, yes, you can do that. But it's not a matter of safety.

If you get into a competitive bidding situation, knowing the requirements can save you money, and lower your bid price, while still maintaining safety. Then, it is a win.

I will have to read up on the 440. I have been following suit for years and have failed to do my due dilligence.
Shame on me

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[supertek65]

This seems dangerous?

[timebuilder]

Am I being told that I do not have to run #8 out to disconnect with 40amp breaker? Or are we talking about load side (after disconnect)?

I always try to follow code, and throughout my time have never been questioned on sizing line side wiring. I just think liability, and it scares the crap out of me!



sent from my Samsung Galaxy Note

The code has specific guidelines for HVAC, because of the nature of the equipment. It's not a like a toaster.

The entire run, from the panel, can conform to 440. The problem is that many techs and inspectors don't actually KNOW the code, so there is a tendency to follow the path of least resistance, so to speak. :grin2:

[timebuilder]

This seems dangerous?

If the compressors and motors didn't have internal overload protection, it would be dangerous.

Since an overload causes these devices to open, they protect the wiring by removing the load. The UL has listed these devices for the purpose, through the equipment listing.

The result is that the conductors are sized to the manufacturer's Minimum Circuit Ampacity, and the breaker or fuse is sized to the Maximum Overcurrent Device values given on the nameplate. If there is no nameplate info, the MOD is started at 125% of RLA, and can be increased to allow for starting current without the overcurrent device opening.

[kamersoutdoor]

This should be its own thread. There is very good info here that has surely slipped through the cracks.
I don't think it is just me that is/was clueless to sec 440 on here or abroad.

sent from my Samsung Galaxy Note

[mark beiser]

It comes up fairly regularly. :p

[beenthere]

This should be its own thread. There is very good info here that has surely slipped through the cracks.
I don't think it is just me that is/was clueless to sec 440 on here or abroad.

sent from my Samsung Galaxy Note

Over the years, there have been a fair number of threads about it in the Pro tech forums.

[supertek65]

so what you are saying is that

the little stuff does not have starters!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

i knew i did not like the little stuff!!!!!!!!





If the compressors and motors didn't have internal overload protection, it would be dangerous.

Since an overload causes these devices to open, they protect the wiring by removing the load. The UL has listed these devices for the purpose, through the equipment listing.

The result is that the conductors are sized to the manufacturer's Minimum Circuit Ampacity, and the breaker or fuse is sized to the Maximum Overcurrent Device values given on the nameplate. If there is no nameplate info, the MOD is started at 125% of RLA, and can be increased to allow for starting current without the overcurrent device opening.

[allenwrench]

I agree completely. For the past few months I have had a recent tech school grad riding with me. Since he has been with me he has learned the procedures to troubleshoot which they obviously don't get in school. Unfortunately it costs the business owner and customer alike. That was one criticism I made in our review of the school in a report my boss and I wrote. I'm trying to get everyone to agree to let me to talk to the next prospective class of people entering this coop program to try to deal with some of that.

Guys I have to agree that there are many schools that are only concerned with getting your money so their salaries can get paid. I graduated recently myself and have had my journeymans for a few months. All I learned in school was simple stuff like what a contactor looks like , sequencer relays, etc. Our trainer we put together in the class room was a joke. It was the biggest waste of money for me ever. I was so dissatisfied that I signed up for co-op my last semester so I could actually learn something and thank God I did . I was completely overwhelmed because I soon realized that I didnt know JACK and I had been seriously ripped off in tech school. THankfully I have learned a great deal through hands on; but still have a long way to go. Hang in there guys, Find someone willing to teach you because the real world of troubleshooting is not taught in school. Or not the one I attended at least.

[supertek65]

there are good schools and good instructors out there!

about a dozen of the best mechanics I have ever met came from Pittsburg State in Kansas!!!!!!!!!!!!

the HVAC program there is off the hook!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

all those guys are now in the union LU533 and at the top of their game and payscale!

[ryan1088]

Pitt state? Really!? Interesting....