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By charliemccraney - 13 Years Ago
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I noticed that my house ac is not working today. I checked the circuit breaker first, it was not tripped. The thermostat is on "cool". The blower is blowing. Outside, the air conditioner is doing nothing. The outside unit is just under 3 years old, still under warranty. Any simple things I can check before I call a pro?
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By MoonShadow - 13 Years Ago
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Is there air coming into the house? Sometimes the vents can freeze up. Chuck
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By charliemccraney - 13 Years Ago
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Well, I feel room temperature air is blowing at the vents.
Oh, and it has been working this Summer, or Spring, whatever season it is.
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By Ted - 13 Years Ago
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You might check that the condensate drain isn’t stopped up. My unit has a sensor that shuts down the compressor if the water level gets too high. Another thing to look for are ants within the electrical panel on the outside unit. Ants do like the relays.
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By The Doge - 13 Years Ago
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It could be your ballast resistor on the outside unit. It is about an $18 part. This connects inline between the power coming in and the compressor and fan motor. It is kinda like a jump starter to get these units going. It will be a metal canister around the size of a pack and a half of cigarettes with wires coming in and out. You can check to see if one end is pushed out. Both ends should be flat but the liquid inside can expand and pop the end out. Whatever it is should be covered under your warranty. Dan
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By miker - 13 Years Ago
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Ok, I was the town electrician, not the hvac guy, but I've been thru this at my house more than once. I can't help with the pressure/ charge side, hooking up the gauges, etc., but at 3 years that should be ok. I'm going to assume you know how to safely go in with a volt meter, or better yet a modern meter or old fashioned solenoid tester (a wiggins). Don't get hurt, even 110 on one side will kill you.
There should be a disconnect at the unit (an off on switch). Door should only open in off. Check the voltage there, 120 to ground each side, and 220 between them. Voltages are nominal, could be 110-120, and 208-240. If theres fuses, check them with an ohm meter, they should be de-energized in the off position, but the top hardware is hot, and easy to get across if you reach in to pull them.
Somewhere in the unit, typically in the air handling unit in the house if its a split system, there is a control fuse that feeds 12-24 volts to the t- stat and controls. Might be a glass fuse, but my new unit uses a modern automobile stab, plastic fuse. Some tstats give an error, or AC OFF-if this blows, but not all (or mine). It will be in an easy off access panel, in a circuit board, and hooked up with small, like 22 gauge, wire. Most of the time, thats where my problem is. Don't know why, but IMHO, they let the HVAC guy run the wires, instead of me.
After that, I call the guy who knows what he's doing, and stand around and try to learn something so I can do it next time.
Be careful, I've lost qualified friends who quit respecting the current.
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By charliemccraney - 13 Years Ago
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This morning I did a test before I left for work. When the system is on and in cool mode, I can hear a hum at the unit outside and nothing else. When I turn the system off, there is no hum.
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By Oldmics - 13 Years Ago
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Is the fan spinning on the air intake? Sometimes they stick over the winters. Use a long screwdriver to set the fan blade in motion-BUT BE CAREFUL !!!!!!!!!!!!!!!!!!! Mine did the humm routine both last year and this year.Once I got the fan to spin the A.C. was O.K. Oldmics
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By The Doge - 13 Years Ago
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Do not leave the thermostat on, turn it off until you get the unit fixed. That hum you are hearing is the compressor and it will overheat. As the previous post suggested, try spinning your fan with a long piece of something. It sounds like either the ballast resistor is bad (most common in my limited experience), the fan is bad or the compressor is bad. Dan
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By The Doge - 13 Years Ago
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Do not leave the thermostat on, turn it off until you get the unit fixed. That hum you are hearing is the compressor and it will overheat. As the previous post suggested, try spinning your fan with a long piece of something. It sounds like either the ballast resistor is bad (most common in my limited experience), the fan is bad or the compressor is bad. Dan
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By miker - 13 Years Ago
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I "think" what the above post is referring to as the ballast resistor is what I would call the starting capacitor. The failure description is correct, but they can fail without expanding the case. If a motor, fan, or compressor, is hung up, there should be an overload relay/fuses/etc, that shuts it down. A control transformer will hum, and if that's the case, at least that end of the controls should be working. But the controls at the outside unit could be separate from the controls at the air handler and the stat. No signal, no start.
I don't know what the weather is where you're at, but last time for me it was 95, and my better half didn't want to hear anything but cold air flowing. Be careful and good luck.
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By charliemccraney - 13 Years Ago
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I'm going to call someone and learn what I can while they're here.
The temperature hasn't been too bad lately. I have a lot of trees for shade.
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By The Doge - 13 Years Ago
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| I "think" what the above post is referring to as the ballast resistor is what I would call the starting capacitor. |
Your correct. I was getting the ballast resistor on my distributor confused with capacitor on the AC unit.
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By 52MERCURY - 13 Years Ago
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I have over 43 years in the HVAC field with WAY too many years doing service work.If the outside[condensing unit]is humming then it is getting low voltage[usually 24 volts].It sounds to me like either you are not getting power[220 Volts],check fuses/breaker,the unit needs a charge[has a leak somewhere]and the pressure switch is not letting the unit run,or the low voltage contactor[has two small wires that power the coil that brings in the contact points,and usually a number of larger wires] may be frozen or burned out,or a bug or bugs got in there and got fried stopping the flow of power to the compressor and fan.If the compressor was bad the fan should still run,if the fan is bad the compressor will run for a short time until the pressure switch kills it.If you have a low freon charge,DO NOT let the service tech just top it off,he[BY FEDERAL LAW] needs to find and repair the leak,Freon does NOT go bad unless you had a compressor internal burnout!! I hope this gives you some help in figuring out your problem!!! ROY.
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By Canadian Hot Rodder - 13 Years Ago
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Charlie,
I am a refrigeration mechanic, when you say the outside unit is humming? Fist thing to check is when you turn on the AC is the condenser fan running? If it is not, that is your problem (the compressor will go off on high head). This is caused by a bad fan motor or bad capacitor. If the fan is running and the compressor is just humming, this could mean that the unit has lost it's charge and possibly seized the compressor. ( usually if this happens though the breaker will trip). You can check a couple of things yourself, first as stated in the previous post, check your voltage going to the contactor. You should have a solid 208 or 230 V. If not, as stated, check wiring breaker panel and all connections. If this is good, if your meter has a capacitor checker, check to make sure the capacitor is reading the correct microfarads. ( the correct reading will be on the side of the cap and you should read within +/- 10%) If all this is OK, you can check the charge simply with your hands, the suction line going to the compressor (should be insulated) should be "beer can cold". The liquid line leaving the condenser coil should be fairly warm about 90 to 100 degrees. If not, this means your unit has either totally lost its charge or the compressor is not pumping. If the suction line is frosting up, then you have a leak and have lost a partial charge. As stated before, DO NOT allow them to top it up, they must find the leak, pump the system down, repair it and recharge the system.
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By charliemccraney - 13 Years Ago
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Ha, it was a bug smashed between the contacts of a relay.
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By The Doge - 13 Years Ago
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That was going to be the next thing I was going to suggest checking for
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By pegleg - 13 Years Ago
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So you really needed an Entomologist, not a HVAC mechanic?
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By Pete 55Tbird - 13 Years Ago
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Charlie, Glad you found the " BUG " in your system. For anyone else with an A/C home system problem a more common failure is a start capasitor. Mine was a 330 volt 145-174 MFD capacitor that failed. This gives the voltage kick to start the AC fan motor running and once it is running , then the compressor will start. A $ 20 dollar part from Grainger. Read about it on google and watch some Youtube videos AND MAKE SURE TO DISCHARGE the old capasitor before touching it. Pete
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By Frankenstein57 - 13 Years Ago
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I used to carry some diazinon crystals or some kind of insect repellent , when I would find the tiny bugs in the contactor on service calls, I'd leave some in the control box. Get familiar with the drain line and fittings coming from the evaporator coil, flush these out every season, save yourself some trouble.
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By The Master Cylinder - 13 Years Ago
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Why all this talk about HVAC on here? You planning on installing Air Conditioning on your car? This picture should give you some ideas on how to mount it and supply power to run it.
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By Y block Billy - 13 Years Ago
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Didn't know there were any HVAC guys on here but I knew there was a plumber! Keep your condenser clean also, I had an old refrigerator and when it got dusty it wouldn't cool, clean the condenser and dust out of it yearly and it would work like new again. Dust prvents cooling, I worked maintenance in a power plant for steam turbines and the ID fan bearings would get dusty and then the temp would climb up to near 200 degrees, wipe the dust off with a damp rag every couple weeks and the temp would drop 20 degrees, amazing how that dust would insulate the heat.
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By Frankenstein57 - 13 Years Ago
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I do both, hvac and a licensed plumber, mostly service. I agree with the comments on a clean system, you can sneak by with a dirty filter during heating season as the high limits take over. But few cooling systems have freeze stats, the dirty filter will cause it to freeze up.
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By HT32BSX115 - 13 Years Ago
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Y block Billy (6/27/2012)
Didn't know there were any HVAC guys on here but I knew there was a plumber!
I became one after I got a $7000 quote to install an $1800 5T on my house! It was a one day job, so I guess 8hrs of work is lessee........7000-1800=$5200.......
for 8hrs ........... ONLY $650 per HOUR!!!!!!!!!! 
MAN! I am in the WRONG BUSINESS!!!!!!!!!!
My system recently died too. It was the dual section start/run capacitor on both the compressor and fan motor.
They're cheap to replace too (unless you pay someone to do it)
Starting capacitors are common on well-pump motors or any high torque AC motor.
When they fail, the motor will hum and usually blow the breaker quickly.
I bought my replacement capacitor from a supplier on EBAY for $20 or so...... new exact replacement
I also bought my complete (brand new Goodman scroll-type) 5T R-22 system from ebay for $1600 shipped to my door!!
..... and several months ago, I bought a new sealed 30lb keg of R-22 on Craigs list for $120!!!
WOOHOO!!
Cheers,
Rick
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By MoonShadow - 13 Years Ago
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Is adding a new system to a ducted heat house difficult? It sure is cheaper to DIY. Chuck
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By HT32BSX115 - 13 Years Ago
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MoonShadow (7/3/2012)
Is adding a new system to a ducted heat house difficult? It sure is cheaper to DIY. Chuck
In my case it wasn't! I already had the "coil cabinet" in the furnace, the power/disconnect was already at the mount point for the A/C compressor.....
All the HVAC "Professional" had to do was set the compressor (on my existing "pad") , run the line-set (about 35ft of copper tubing) in a VERY easily accessible semi-crawl space , plummer-tape it up and silver solder it all in and suck it down (with a vacuum pump) !! AND run the control wiring along with the tubing.
The Compressor was pre-charged for about 18' of tubing already, so it needed maybe a lb or more of R-22 to "top" it off. (although it works as is)
It took me most of the day to get all the tubing in place and make a little 3x3 pad of concrete. But I was doing a lot of visiting with the neighbors too!
I am figuring that someone that does it for a living would have taken half as long as I took and it took me all day. But lessee......... Less than $2000.....vs.....$7000. It was a pretty easy choice for me.........
AND I already had a vacuum pump! and an oxy-acetylene torch, and I scrounged a couple sticks of silver solder!
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By Frankenstein57 - 13 Years Ago
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Not all HVAC shops are going to charge you that kind of $$$$ You just happened to call the one who did. Why did you go with R-22? The stuff is being phased out, the cheapest 30 lb jug around here is $330 + tax. Just be aware on the ebay Goodman equipment, I put in two furnace & ac combos for my friends dad and his neighbor, One of the furnaces needed to have the inducer assembly replaced on a home sale transaction. The local Goodman dealer wouldn't honor the parts warranty because they bought it on the internet. We had to buy the parts.
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