This is a great question and I get it a lot.  Of course like much in HVAC there is no straightforward answer.  It depends.  In my experience the Air conditioners and heat pumps seem to live right around the 15 year mark.  Past that and you are definitely in the money and earlier than the 15 year mark is not uncommon.

Now when I say ‘last’ I mean when a major component fails or it begins to leak.  Compressors can lock up, short a winding or just go bad at virtually any time.  Usually there is something to blame to make that compressor die an early death.  The typical AC compressor is a $1500 to $1700 replacement and with R-22 freon price going through the roof than replacing the whole unit is typically the best bet.

Also with the newly mandated R -410a mandates and it’s ‘earth friendly’ nature we are seeing many coils that are prematurely leaking.  I am talking evaporator coils on those units.  I don’t think manufacturers were up to designing a coil that would operate under twice the pressures that r-22 had to.

So when I say lifespan it means the major components.  We can change a condenser fan motor in Phoenix for relatively cheap ($300 - $400) and replace run capacitors for not much either.  But when it comes to the biggies like that compressor and indoor coil often times it can tip the scales to get a new unit.

The last thing you should take into account is the operating efficiency of the unit.  If you are running an 20 year old heat pump and upgrade event to a 13 SEER (which is the minimum now) you will enjoy a large drop in electric bills during the summer.

So if you are at the 15 year mark, then yes, start thinking about new. If you are at the 20 year mark than you have beaten the odds and you can keep coasting or look for that new higher efficiency and give us a chance to seal all of those leaky ducts and balance out those hot rooms.

You guys know I rail on the commission based ‘tech’ idea.  The conflict of interest that goes with sending out a guy who is going to be paid based on how high he can juice the bill.  Well, tune-up time is the Olympics of this sport….

First off there is no such thing as a ‘tune-up’ – your HVAC system is not a car and does not need any tweaking.  Preventative maintenance on your unit, especially in Phoenix Arizona (where we see huge loads on units in summer) is smart.  That involves running the unit under a load and checking refrigerant levels, amp draws at start up of the compressor and inspecting the contactor and testing run capacitors.  Now if you capacitor is outside the +-5 MFD range than yes I would recommend changing it but not if it just looks like crap.  Some run caps run for years and look awful. 

The bottom line is like we do in Phoenix, ask if the tech is doing preventative maintenance.  Follow them around and ask questions, get involved.  If they get cheezed off at that then kick them out.  Remember this is not rocket science and if someone cant explain what they are doing and why than maybe they don’t really know what the xxxx they are doing.

There are literally dozens of things that can go wrong with a heat pump but in this note I will touch on a couple of the most common.  In Phoenix Arizona this is the heart of heat pump country.  Heat pumps work great in our low desert regions where temperatures rarely drop below the freezing mark.

During normal operation in Phoenix your heat pump will build ice on the outdoor unit.  This outdoor unit is essentially now your evaporator coil and the indoor unit or indoor coil is the condenser coil.  

The outdoor unit of your heat pump in Phoenix will gradually accumulate ice on the coil if there is sufficient moisture in the air.  Every 30, 60 or 90 minutes (depending upon what your installer set the defrost thermostat to) your phoenix heat pump will 'look' at that outdoor coil and see if there is ice on it via a defrost thermostat.  In Phoenix your heat pump will not need to defrost often due to the low moisture content of the air.  If the unit does not go into defrost, ice will continue to form on your heat pump and in Phoenix the unit will eventually stop heating.  You can 'manually' turn the air conditioner on at the thermostat to simulate the defrost process and that will melt the ice until you get a new defrost board and/or thermostat to correct the problem.  In Phoenix air conditioning mode there is no defrost necessary because the indoor coil never gets below freezing.  The coil of the phoenix evaporator on you air conditioner is no colder than 40 degrees.  If you have frost or coil on your phoenix air conditioner evaporator coil than you are low on refrigerant or your Phoenix air conditioner has an airflow problem.

Ok you want it you got it from Merritt at thermal-medics.com

Here is the step by step methodology known as a/c troubleshooting.  How to diagnose your air conditioner or HVAC system in an ordered, methodical and proven way to get the answers you need.  If you take some time, get educated, watch the videos at http://www.thermal-medics.com/ that I have made you can save a lot of money.  Commission based A/C techs love nothing more than an ignorant consumer.  They can sell you anything from a surge protector to float switch to even up to a new unit for a simple run capacitor or burnt wire.  Read "the worst a/c story ever" if you need any more encouragement.

• Is air blowing from the registers? Yes or no

1. yes, is it warm (ambient) or a little cool or actually hot (on a demand for cool)?
2. is the condenser fan motor and compressor also operating?

• if all motors are operating and you are getting warm to ambient air than probably a refrigerant issue
• that can come in the form of low refrigerant (slow leaks) 
• big leaks
• leaking reversing valve if a heat pump
• clogged metering device (txv, fixed orifice, or capillary tube)
• duct leaks

• if air is warm at registers check condenser fan motor and compressor - if not operating check run capacitors to see if bulged or popped - follow link to photos at the image glossary
• does the condenser fan blade turn freely with a long-handled screwdriver? or is it binding up?
• binding up usually means it is seized up - freely could still be good  - test the run cap first before replacing the condenser fan motor - awesome video here on tips and tricks
• compressor may or may not start back up if run cap on fan motor is popped - it has an internal overload protection that must reset at appx 115 degrees to operate again.  I sometimes use bags of ice to cool down the compressor quickly in a pinch - or just have a cold one..

1. Is there a breath of air at the registers - it may be cool but very low airflow?

• dirty evap coil
• leak in ductwork (see the door trick article) on right side of home page
• very dirty filter (very rare)
• if this is the case the compressor and outdoor fan motor will probably trip on overload

How to clean an evap coil properly?  Call or email me at thermal-medics.com 

1. no, when you operate the thermostat does any other modes work (i.e. fan to on or heat??)
2. is there ice on the big copper pipe (suction line) when the outdoor unit (compressor, condenser fan motor) comes on? if yes than shut off the system to avoid adding a 0 to your final repair bill.

1. No no other modes work and nothing at all comes on - indoor or out - dead as a doornail:

• control problem
• change batteries in t-stat
• float switch backed up
• 5amp fuse in air handler (there is a reason it popped - gotta find out why)
• transformer blew (it happens)
• bad wiring
• main breaker for whole unit

This is just a short list to get you going the right way and keep the dirt bag salesman 'techs' from ripping you a new one on a service call.  Call or email me anytime for detailed step-by-step help to get to the root of the matter and often times fix your unit yourself.  Read the testamonials -  if you give me 10 minutes I can save you hundreds of dollars!! 

Merritt  info@thermal-medics.com

This is tough question to answer. It really depends upon the specifics of your situation.

I will say most contractors will push a new unit all of the time because that is where the biggest profit is for them. Often times a simple fix is overlooked and an estimate given that is so sky high that buying a new unit starts to make sense.

I personally think that is BS and I hear stories from you all the time on it. A simple leak fix is a $300 job but someone will price it at $2000 with a bunch of BS about government refrigerant mandates, efficiencies etc and tell you it will only be $4500 for a new unit.

There is a time when a new unit makes sense. I have babied along units that are 25 years old and they run like champs. But on one of those systems if the compressor locks-up or grounds out than yea, it makes sense to go new.

I give the average lifespan of a modern A/C or heat pump system about 15 years. In many cases that is even too generous. So much of the modern stuff is poorly made crap from overseas and you are lucky to get 10 years out of it.

For that reason if you do go new get at least a 10 year warranty on the parts and lifetime on the compressor if possible. I know Goodman does that now and it really starts to make sense.

Call or email me any questions you have. If you get an estimate and need a second opinion – let me know. Often times I can tell you how that simple fix can keep you out of the crosshairs of a commission based tech.

Ok these are some quick and dirty rules of thumb when describing A/C tonnage, BTU's and how to size a unit for a home.

One ton of cooling = 12000 BTUS and is designed to cool approximately 400 square feet of living space.
So, if you have a 2000 square foot home you might have one 5 ton unit or two units a 2 and a 3 ton.
These are rough numbers so your results may vary.  When your home was built someone (hopefully) did a calculation to determine what size unit to put on that particular home.  If the home was made of glass then obviously the unit would be sized larger, for example.  I live in a 3200 square foot home but get by with a 3 ton split and a 3.5 split system.  A little undersized but I have returns that go under the concrete slab and 2x6 framing with good insulation.  My system is sized properly.

Now why not just upgrade the unit and stick a couple of 4 ton units at my place? I mean more is better right? NOOOOOOOO!  My units run often during the summer but they turn on and stay on.  If I upped the size of the units then they would 'short cycle'.  A fancy way of saying turn on and off all the time.  If I selected 77 degrees at the thermostat and the unit kicked on at 78 it would pull down to 77 in a hurry, no doubt.  But, and here is the kicker, it would not run long enough to dehumidify the air and thus run back up to 78 in short order and the cycle repeats, over and over again.

The hardest thing for any motor, and I don't care if it is your lawn mower, car, ceiling fan or A/C unit is to turn on.  The amp draw of an electric motor is higher at start up to overcome the torque necessary to get up to speed. Example, my compressor will momentarily draw 60+ amps at start up and then run at 14 amps.  That is a lot of heat in a short amount of time and motors HATE heat.  It is their Achilles heel.

Ok, first of all I know this is not some urban legend in the HVAC world, but it easily could be.  I know this individual and I beleive his story.

Back up 15 years or so in Phoenix during a hot summer.  This fellow was just out of trade school and got his first job at a small Dad and son outfit.  Well, of course, he was nervous and wanted to make a good impression.  He rode with the dad on day one. (another story-another day) He rode with the son on day two.The first call was some routine, low freon, gas-n-go.  The next was one for the ages.

They knocked on the door and an elderly woman answers and says her A/C is blowing hot air.  Granted it is in June so things are heating up quick and she only has one unit.  During the course of the discussion the 'son' finds out she is a widow recently and she does not know much about A/C (except it dosent work).  Well the two pull the ladders and go up on the roof for a look.  Package unit, pretty straightforward.  The new guy looks in from the top and notices a lead on the compressor is burned off.  He tells the 'son' thinking, "Wow, I just proved myself."  The son grunts and says lets go on back down. He tells the new guy to go wait in the truck while he talks to the customer. When the son returns he says lets go out and get a bite to eat and get a couple of things.

By now the new guy is confused. First they stop for a burger and the son pays.  He gets a whole speech about how tough the business is, blah blah blah...Then they go get the local newspaper from the convenience store.  Next they stop by a hardware store and get two cans of black lacquer spray paint.  (Oh no, you say but yes they do).  

They return to the home, remove the top, fix the wire for .25 cents and layout the newspaper.  They spray paint the compressor a shiny new black and put it all back together.  $650 later they are out the door with a 'new compressor' installed.

You are asking does this kind of $xxt really happen? Yes it does.  Your job is to get educated, ask questions and be involved.  I got into this trade after my parents were scammed by some local dirtbags. Do I want to get even, yes.  This is why I write this stuff down and share it. 

By the way did you know if you have only one unit in your home and have small children or elderly folks living there some, reputable, companies will prioritize your call. Make sure if you know someone who is older and lives alone has that information....Anyone can contact me at http://www.thermal-medics.com/ or pick up the phone to call.  My phone number is on the website.  I don't care if you call or email from Fargo or Florida I will get back to you and I will answer your questions.  The website and this blog are FREE for anyone, DIY, homeowners, general questions or anything related to heat pumps and A/C units.

If you have one of the return air grilles pictured below in your ceiling or wall, listen up.  The fins are bent to hide those ugly filters we put there to keep our coil and air clean.  The downside to the bend in the grille is a reduction in airflow and sometimes a nasty whistle.  Do yourself a favor, go out to a big box store and get a sheetmetal hand seamer tool (or borrow from someone).  Straighten out those grill vents and you will increase your airflow 20% RIGHT NOW.  Don't worry the grille will not break just take the seamers and straighten them out in one motion.

• Change the filter (duh, every 3 to 5 months is fine)
• Check the air split, return vs. supply. It should be a 20 degree difference.  ex. 80 degrees at the filter, 60 at the register.  You will be off by a few depending upon where you are in the house relative to the air handler.
• Check that the condensate drain is dripping freely and the backup is dry.  If your horizontally mounted air handler is in the attic, go up and take a look.  The drip pan should be dry (and no rust in it). The pvc outlet somewhere around the outside of your house should be dripping freely in the summer or high humidity times of the year.  If your air handler is mounted vertically in a closet or garage, you will not have a backup pan.  The drain will run via gravity outdoors or into a small pump that will energize when water reaches a set level in it.  The water is then pumped through a line outdoors.  You will know you have a problem here when you change the filter and notice a rust stain on it or it may be wet itself.  
• A backed up condensate line is a minor plumbing problem and can be DIY'ed very easily.  Simply use a shop-vac at the outdoor pvc drain spot and suck through the obstruction.  Usually the obstruction is in the p-trap.  You may have to cut the pvc line with a hacksaw and clean the trap then simply reglue the pvc together.  Simple and you saved and easy $150!!!!!
• Clean the outdoor coil.  Pull power to the unit at the disconnect (shotgun fuses or pull fuse).  Spray (no pressure washer) between the fan blades to the outside.  Be careful not to bend the fins.  Re-establish power to the unit.
• You can pull off the electrical cover to the outdoor unit if you so desire and inspect the contactor.  Be sure to pull power to the unit before doing so.  If the contactor is burned or pitted it can be replaced easily ($25 part).  Again, be sure power is pulled before opening the electrical case.
• What about checking the freon level?  This is a great question and it relates back to #2.  If the unit is cooling properly in the summer when there is a 'load' on the unit.  I am in the camp of not believing in hooking up manifold gauges to the unit.  My thought is many techs are careless in not using proper procedures in purging their hoses or use the same gauge set with multiple refrigerants and thus will probably do more harm than good.  That is just me.  If you are getting the 20 split in the home than I would leave it be.

Ok, great question.  You can go into the large home improvement warehouses and buy chainsaws, table saws, electrical panels up to 460 volts as well as many home items that will kill you in quick order if you dont know how to use them. 

If you go in and ask for a condenser fan motor the guy/gal (if you can find one) gives a blank look and points over by the swamp cooler stuff. They are not there.  The blue home improvement store has a few duct work items including flex duct, elbows, pookie (white mastic for patching leaky vents) but thats it.

In the Phoenix Valley of the Sun area click here to get free delivery and my diagnostic help to get you the right part at the best price..

also check out our other blog at http://phxheatpump.blogspot.com/

We are here for one reason and one reason only; that’s to give you the help you need to diagnose, fix or just learn more about what the heck is going on with your A/C unit.  There are a myriad of problems that can occur when trying to diagnose a problem but I have learned over the years to stick with "Occam's Razor."  What is that?  Well, simply put it is the simplest, most common problem is probably the culprit until it is proven to be wrong. 

As a Tech out in the field, I have to be able to walk up to a unit with a problem and quickly figure out what is most likely wrong and fix it quickly.  I use a very simple and quick methodology to achieve that diagnosis.  Occam's Razor is always in my mind because there are a few problems that occur most of the time and the random, hard to track are rare.   Sooooo, how does that relate to us?  Well my Q and A session with you can cut to the chase to get us in the ballpark and then narrow down from there.

Let me give you an example: Let's say your complaint is simply the A/C is not working.  Ok, does the indoor blower motor come on when you select the thermostat fan switch to on?  Yes it does you reply.  Well we just eliminated a ton of components.  Most notably the indoor fan motor and it's associated run capacitor, the transformer (that converts 240volts to 24 volts for thermostat and control use), etc.  Now we move on from there.  It took 10 seconds and we just eliminated half of your system from suspicion.

Remember stick with the odds until they prove you wrong.  I have had a few head scratchers and trust me they are out there but they are rare.  It's not rocket science folks.

check back soon or visit us anytime here or our other HVAC DIY blog http://phxheatpump.blogspot.com/