anyone know anything about home air conditioning?

[Rodnik]

thanks a million everyone.

this is why i love this forum...

 

 

One thing to try before you call the repair man...

 

Take the cover off the unit and tap the motor *lightly* with a hammer while it's trying to spin up. These things are generally squirrel cages that have a centrifugal switch that can lock up, and a slight rap will sometimes free it up.

 

Another thing to consider..the motors generally have a starting capacitor---which go bad *much* more often than motors do. You can remove the capacitor and check it with a meter. Replacing a cap is MUCH cheaper than replacing a motor.

[tanker22]

I worked heating and air for a few years before getting into stationary engineering. Could be alot of diferent things ranging from yor T-stat to relays and capacitors. Most these are easy fixes and the service call will cost more than the parts to fix it. As for comming back on after letting it sit for awhile does sound like the thermal overload on the blower motor. Most have an internal one that measure temps accross the motor windings, older ones have external ones and can go bad or a wiring problem. You usally see these on the outside on the compresor on the condeser though. has me wondering though if its been running fine since then that the motor isnt the problem. I am not a big fan of attic systems since they are hotter, this could also be the problem. How is the ventalation up there? Dirt build up and excessive heat can cause it to trip on that as well. Living in florida this isnt the set up od choice as far as I'm concerned. Another thing that hurts you if the system is old the blower fins get build up with gunk and slow air flow causing the motor to work harder, would advice you to get someone in there to pull the whole squirrl cage and have it cleaned. Duct work is another thig that cuts down on air flow causing to to run longer, should be cleaned within a few years if its a new house or at least every 10 years IMO.

 

Yes filters are a big issue, I dont know how many calls I went on for people not changing or having filter in place that caused proplems, The cheaper ons shouyld be changed monthy at least. I have 6 mo ones in mine and change them every three months if I can. This keeps all the junk from building up on your evap coil. A frozen evaporator usally means restricted air flow if your freon level is good, a change in filter and cleaning usally fixes the probelm. If its still doing it after filter change your low on freon to the point that the system will run dry which now you risk compressor problems. It is a sealed system and should not lose anything, dont let these jokers keep comming out and adding freon to your system over and over, its to expensive over time. Have them do a leak check with dye or an electronic sniffer, most leaks are out on the condesser coil anyways I've found or at the connections to the evaporator inside.

 

Clean your condenser acouple times a year if its running alot! I cant stress this enough. If the fins are all plugged up your not getting heat transfer so your system has to run longer and harder to keep it cool in your house also increasing your bill and leading to more serious problems. Shut everything down inside and just pull the breaker, should be outside buy the unit. Use a med. pressure narrow stream hose, your not going to hurnt anything as long as your not spraying it directly into the electrial components. Let it dry for about 15 min then power it back up. Trust me, this is a good thing to do if your not in the habit of it.

 

If your condeser fan and compressor are running fine outside but no air flow in the house the problem is inside. More often then not if your having a problem and everything is ok inside, your fan lost a capacitor on the condenser. No air blowing out the top is a sure thing 8 out of 10 times this is your probelm. Just shut everything down so the compressor isnt damaged, this is the most expensive piece of equipment to replace, take care of it. You would be looking in the range of at least $500 to put a new one in.

A capaciter usally runs in the area of about $15-25 if I remember correctly.

 

If I was to guess though, it sound like you have a heat problem in the attic and things need to be cleaned as well. Dust, dirt, ect traps heat and that is a bad place for it.

Hope that helps, any other questions dont hesitate to ask

 

Oh, I would not recomend checking your capacitor as Rodik suggested, unless you know what your doing, this is a bad thing. Although they do go out often this is an easy fix and the motor wouldnt have restarted more than likely.

They hold a charge that needs to be removed first. I took 440 volts through my hand one time that left a nice scar when I first started, not fun. Leave stuff like that to the people that know how to do it. Also if the switch in the motor is going out your going to need a new motor anyways eventually, hitting it isnt my first choice unless an emergeny. May void warrenty as well if the damage is noticed. Sorry Rodnik, didnt mean to bust on you

 

Chris

[tanker22]

Acouple other things I just rememberd for general info in regards to capacitors. Most are oil filled, it you see any leaks its bad. Also the tend to get a large buldge on the top or side aslo meaning they are bad. Something to look at as any easy way to identify a problem.

 

Another couple things I ran accross that you can do for yourself to save a service call. Easy stuff. If you have a digital T-stat and there is not display could be this. On your furnace there is a power switch to the control voltage, make sure it is one. Also most have a plug fuse with it, check to make sure it isnt blown. This will also cause your unit not to run on the inside. Very easy fixes you can do yourself and save a $60 service call for a guy to come out and flip a switch, yes I've had to do it before

[kristof65]

Ok, I'm not an HVAC specialist. But I am long time tech in other fields, and I run into this a lot, particularly now that I'm doing tech support, so I'm going to emphasis it here:

 

If you don't have basic troubleshooting skills, aren't mechanically inclined and/or don't have any idea what you are doing, trying to do it yourself "to save money" can often cost you more in the long run. Sometimes even if you do have the base skills it can cost you more money.

 

I can't stress that enough - sometimes it pays to hire the professionals. And remember that with a professional who has a good reputation, you are often getting more than the repair itself - you're getting things like warranties, free call backs, etc. This applies to everything, from car repairs to HVAC to fixing your dishwasher.

 

Now, that said, there is a LOT you can do yourself that doesn't require calling someone. There are several good books on home repair (Reader's Digest publishes a couple) that contain step by step instructions on things you can do yourself, and routine maintenance. Things like cleaning your system are those type of things. Depending on your skill levels, there may be a lot of other things you're capable of to save yourself money. But it's important to understand your own limitations.

 

Unless they're inexpensive parts, I don't recommend just throwing parts at a problem. Sure, you may be just as capable of replacing a blower motor as the HVAC pro, but how sure are you that's the problem? Do you really want to replace a motor, only to find out it's a bad wire?

 

Point is, if you hire a pro, and they make mistakes like that, they're on the hook for them, not you (assuming they're a reputable company). A personal example - I'm perfectly capable of soldering copper pipe together for plumbing. Yet I _always_ hire a professional plumber to do those things. Why? Because if I screw up, and a leaky pipe damages my stuff, it's coming out of my pocket. If a professional screws up, and a leaky pipe damages my stuff, it's coming out of his pocket.

 

Basically, know your own limitations - know what you're capable of, and what can get you in trouble. Don't be afraid to learn, and use the DIY info/resources available, but don't be afraid to call in the pro BEFORE you get in over your head.

 

And if you do call a pro, be completely upfront with them on everything you did - even mistakes - because the last thing you want is them spending an hour tracking down something you could have pointed them towards in five minutes. Don't be afraid to ask them to show you the things you can do yourself, too. While they make decent money doing things like showing up to flick a switch, most of those techs have such busy schedules they'd rather avoid those types of calls all-together, so they're usually happy to show you.

[Joe Kutz]

Just a quick point - while it could be an issue with freon, dirty coils or other things - the situation states that when he tried the heat...nothing happened as well. In most modern (anything in the past 30 years or so) the heating circuitry is pretty well isolated from the cooling circuitry. If you switch the heater on and your expansion coils are frozen up, you normally get air coming out of the system - but it will have a very distinct feel/smell (very humid and almost musty). When the problem is within the blower circuit itself (either thermal overload or startup circuitry) you will not normally have anything happen on heat or cool...though once things have enough time to cool off and reset they will often start back up (one of the most common thermal overload switches is simply a bimetallic switch that will bend when it gets hot - once cool it straightens back up and everything will work again). This makes it somewhat difficult for a lot of the newbie techs which are sent out on service calls to diagnose. By the time they show up - everything has cooled back off and they will be able to turn it on again just fine.

 

In terms of a problem that only exists with the AC unit though...things get a lot more complicated. In order to avoid burning out expensive compressors or having other issues there is a complex network of sensors, pressure switches and other bits. If one of these goes bad (or simply has connection issues like corrosion) you will quite often have problems that are more difficult to deal with. Quite often specialized tools are needed (gauges for checking high side and low side pressures - coolant fill fittings and regulators - specialized tools just to get in deep enough to test the electrical parts). With those, I would generally recommend you contact a professional if for no other reason than you may end up spending more on tools than you would having a tech come out and deal with the issue.

_______________

 

Anecdotal though it may be, when we first moved up here from Florida last year we got a rental house for a few months while we looked for a permanent home. After about a month the blower would run for awhile just fine - but than stop and not come back on for several hours. Since it was a rental, I was not going to be on the hook for the repairs or other issues that came into being as a result of the problem. Anywho, I troubleshot the system and located the problem (yet another blower motor with a bad bearing...it actually ended up burning out the startup circuit as well as a result...but that was a cause of the increased current required to get the motor spinning in the first place). I called up the land lord and told him what the issue was. He called the service people (not a small HVAC firm - national, factory certified and all that). They sent a tech out to service the problem. I told him what it was and then went out to do some more house hunting while he fixed the problem. Came back several hours later and the blower was still in place but the control card was missing. Well, they replaced the old control card with a new one (the old one worked perfectly fine) and it still didn't fix the problem. I told the tech (different tech this time...same company) what the problem was and my wife and I went out to get some dinner (mind you this is January in South Dakota with no heat...we didn't feel like hanging around the house till it was fixed). Came back after dinner to find the new control card still installed and a new set of relays in the startup circuit. Still no heat, and no HVAC technician hanging around. Right before we left the house for the hotel, yet a different HVAC technician came to the house with nothing but his multimeter and a set of screw drivers. I told him what the problem was (as I had told the two before) and waited for him to poke around a bit. He finally came to the same conclusion that I did (wasn't much left...they changed pretty much everything else to be changed) and told me it would have to wait until the morning since they would need to get a new motor.

 

Final tally of letting the professional, factory certified, repair techs doing a simple 30 minute job...7 hours of billable labor (at $65 per hour) and over $500 worth of parts. All of which the land lord was on the hook for. When I took a closer look at the squirrel cage assembly the actual bad bearing was press fit - not a permanent part of the assembly. 20 minutes with an arbor press and a $10 bearing could have fixed it all...may have even been able to repack the bearings and save more money. Just because you hire a pro - it doesn't necessarily guarantee that you will save money in any way...or get it done right. If you read the fine print you will often find that as soon as a part is installed you are on the hook for paying for it even if it doesn't fix the problem. You will also find that as long as industry approved procedures are followed it doesn't make a difference if they spend 7 hours doing a 30 minute job and charge for $500 worth of parts which should have been no more than half that...you still pay, and they don't have to explain themselves. Since many HVAC techs now are not really HVAC techs (i.e. - they follow a flow chart of pulling and replacing parts as opposed to even understanding how to troubleshoot the system) the industry approved methods of fixing your AC will often cost more than the old school troubleshooting methods.

[kristof65]

If you read the fine print you will often find that as soon as a part is installed you are on the hook for paying for it even if it doesn't fix the problem. You will also find that as long as industry approved procedures are followed it doesn't make a difference if they spend 7 hours doing a 30 minute job and charge for $500 worth of parts which should have been no more than half that...you still pay, and they don't have to explain themselves.

While this is true, if you go with a good company, and read their service contracts carefully before signing/paying, you can avoid all of these. You can line out contract provisions and initial them, which indicates you don't agree to those terms. There are other methods of resolving the problem as well, in terms of resolving disputes - going to the media, small claims court, etc. If you got the company name through a referral - realtors and TV stations often have referral networks, you can use those as leverage against them as well until it's resolved to your satisfaction.

 

It comes down to being a savvy consumer, which is a skill anyone can master - deal with reputable companies, read the fine print and cover yourself by doing things like asking for the old parts, and holding on to them until you're satisfied.

 

Since many HVAC techs now are not really HVAC techs (i.e. - they follow a flow chart of pulling and replacing parts as opposed to even understanding how to troubleshoot the system) the industry approved methods of fixing your AC will often cost more than the old school troubleshooting methods.

Unfortunately, this is becoming the norm - I call them black box technicians. And since consumers are becoming accepting of those repair "methods", they're more profitable for service companies. The only way to fight that trend is really to stick up for your rights as a consumer.

 

At some point, I'm going to hire a bunch of ex-Navy guys who've been through the Navy's troubleshooting training, and start my own troubleshooting company - we won't fix your stuff, only narrow it down so you can fix it yourself or hire someone else to do the specific job. Our entire focus will be on the troubleshooting that these other companies don't want to do anymore.

[tanker22]

Just a quick point - while it could be an issue with freon, dirty coils or other things - the situation states that when he tried the heat...nothing happened as well. In most modern (anything in the past 30 years or so) the heating circuitry is pretty well isolated from the cooling circuitry

 

Not necessarily, your control power all goes through the T-stat regardles of heat or cold. You also have your relay at the furnace with the three wire coming from the condeser that controls the blower for both as well. Your T-stat is going to send your signal to the furnace when it gets a call for either heat or cool. Only difference is the speed the blower is going to run at, High speed for cool and low/med for heat. I keep my blower running year round in the On position to circulate air in the house, havnt shut it down at all in the last 5 years except to service it twice a year. You can switch between heat and cool and the only thing it will do is change the speed on it but will continue to run regardless of it calling for heat / cool or nothing at all.

If his blower and furnace are in the attic as he stated that still explains the heat overload and nothing happening on either heat/ cool until the motor cooled down.

 

There again as kristof stated it could just be something eaisy like a loose wire for all we know, alot of little things that could be going on. Has he had this problem before?, how old is the unit?, mice even chewing at the wires causing a short, seen that as well. Alot of variables without being able to put hands on it and trouble shoot.

 

Your right though, alot of guys are turning into just parts changers that I've seen. I'm in a rental and my garbage disposal goes out. I call the land lord and they send a repair man over. He looks things over and decides in about 5 min. that the disposal itself is bad. I already know what the probelm is haveing checked it. I ask him if he had checked to see if it had power at the outlet. I get the deer in the head lights look as he goes about doing this after I said something. Nothing there. Breaker is fine and its just the outlet had a old wire that grounded out. Lesson learned- these guys mark up parts usally 100 to 150%, thats were the money is at. If I hadnt of had the back ground I do I doubt I would of caught that oversite on his part and would of had a new disposal that still didnt work.

[Doombringer]

just a quick update...

so far so good, it has been running fine ever since.

i'm still going to stimulate the economy a bit with my stimulus check once i get it and have some maintenance done.

 

i was going to say that the unit hasnt had anything done to it for the 8 years that i've lived in the house but i forgot, i lost the motor to the outside unit compliments of a florida storm about 5 years ago and they cleaned everything up including the inside unit when they replaced that.

 

the unit hasnt ever had any problems other than that.

[Rodnik]

Oh, I would not recomend checking your capacitor as Rodik suggested, unless you know what your doing, this is a bad thing. Although they do go out often this is an easy fix and the motor wouldnt have restarted more than likely.

They hold a charge that needs to be removed first. I took 440 volts through my hand one time that left a nice scar when I first started, not fun. Leave stuff like that to the people that know how to do it. Also if the switch in the motor is going out your going to need a new motor anyways eventually, hitting it isnt my first choice unless an emergeny. May void warrenty as well if the damage is noticed. Sorry Rodnik, didnt mean to bust on you

 

No worries. I'm always comfortable with testing caps and such (so it's second nature to discharge them), as I was speaking from the point of an electrician (at least in another life, although I do keep my license current)---and I missed the part where they said the motor had restarted.

As for the centrifugal switch---I've tapped on several motors that ran for a number of years before they actually went bad---especially those motors that are somewhat exposed to the elements. But obviously, I would agree the best advice always comes from someone that has worked on the units, such as yourself,---so you're word *should* trump mine...I just know motors and industrial controls----I don't know much at all about hvac.

 

Regardless, the cap in the case shouldn't have a full 440 on it at max here in the states (on residential applications, that is--and this is still HIGHLY dependent on the capacitor application/size/etc.)---and they'll bleed off significantly just sitting in the circuit---these are electrolytic caps, and one "downside" is high bleed-off current. To discharge it, you simply remove it from the circuit, and use a rubber-handled screwdriver to short it to ground or from lead to lead. No real danger as long as you don't touch the leads with your bare hands---which is second nature to folks that work with 'em. If you know *anything* about electricity, I would never hire a service man at $90 hour to replace it.

 

Speaking of which...we used to toss these things to folks with a "Here, catch!"---and watch the little dance that people do...8)

[tanker22]

No problem Rodnik, I am by no means an expert having only worked in the field for acouple years before switching to boilers ( better pay ) and its been a good 4 years since I've done anything much with HVAC stuff.

 

In regards to Caps though, I have used the screwdriver to release the charge but this isnt the method of choice ( old school tech stuff ). There is a chance of damaging the internals on it (rare but does happen). You can pick up a bleed resistor that is specialy made for this now if you do this kind of thing alot and is probibly the way to go with someone elses stuff unless you want to chance putting a new one in at your cost. Just trying to give some helpfull advice on it.

 

Alot of the duel Caps on residential units do run higher voltage though, 330v/ 440v unless I'm mistaking. Thats what I was working on when I got zapped was a compressor. Still dont know exactly how I did it, the top of my hand was resting on the underside of the metal covering and I must have crossed leads with my screwdriver when I was putting it back in. Next thing I know I'm on my butt about 10ft back with a numb hand and arm

[Rodnik]

In regards to Caps though, I have used the screwdriver to release the charge but this isnt the method of choice ( old school tech stuff ).

 

I guess that speaks to my age..

 

Alot of the duel Caps on residential units do run higher voltage though, 330v/ 440v unless I'm mistaking.

 

You're absolutely correct---it's more a matter of plate spacing, cap design, circuit design than it is input voltage and such----they just have a tremendous bleed off is what I was gettin' at. As long as you don't touch them right after attempting to power the unit on, it's usually not much of a problem outside of a "little shock".....if you catch 'em shortly after they've been charged fully---like you said, it's a nice little "pow" that'll sometimes make you see stars....

 

Which leads to the next fun little exercise...wait until someone is working on one---then goose 'em with the battery drill and pull the trigger...(bit removed of course)....

[Joe Kutz]

We used to charge up caps and leave them sitting on the workbench. If a newbie was around, we would have them go grab that part... If not, someone would inevitably see stray parts sitting out and put them back in benchstock.

 

Best one. Our director was doing a VIP tour through the shop and he had a habit of picking up stuff and fiddling with it while he talked. Popped him pretty good - right in front of a couple congressmen and other senior civilian types. He stopped grabbing stuff off the benches during tours after that.