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1/25/2018 7:38:29 AM
Posted: 7/15/2002 9:04:00 AM EST
I've got a two-story house with a separate A/C unit for each floor. The upstairs A/C has gone down and it's 87 degrees upstairs with the vents blowing warm air. This started yesterday. I changed out the air filters in the blower units up in the attic, but that did nothing for the problem. I checked all the breakers and switches, and all are good to go. When I went outside to the compressor units on the side of the house, one of them turned on, ran for a while, then turned off again, and was completely quiet while it was off. The other one would seem like it was going to turn on --would start to wind up-- then just stop, but the whole time gives off a low hum or buzz. When I called for service, I was told that no one can be out here until the day after tomorrow. Any suggestions, aside from "sleep on the sofa?"
Link Posted: 7/15/2002 9:08:40 AM EST
Mine did the same a while back. Turns out the fan motor was out of oil. I dont know if newer heat pump motors have this, but mine had two little caps you could pry off to oil the bearings. Test out the blade by making sure it spins easily. If not, the bearings may be bad. -Nuke
Link Posted: 7/15/2002 9:13:23 AM EST
Sounds like the compressor motor or maybe the "starting" mechanism. I guess you had no problems until it just stopped. I would be surprised if it's more than a breaker type fix.
Link Posted: 7/15/2002 9:17:19 AM EST
Originally Posted By Jarhead_22: Any suggestions, aside from "sleep on the sofa?"
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Well, that and, PRAY you don't need a whole new two unit system like I did. Almost 5K later,and I'm all nice and cool (cept'n fer "under the collar")
Link Posted: 7/15/2002 9:20:44 AM EST
Jarhead 22 if I understand what you have written the upstairs unit is low on freon. the outside unit (condenser) has a low pressure switch so the air handler unit upstairs runs and the matching condenser runs for a minute then when the pressure gets low it shuts off for a minute. When it shuts off the pressure equalizes (low pressure side goes up and high pressure side goes down) and when the low pressure side goes up it reactivates the low pressure freon switch and the condenser comes on, runs for a minute until the low pressure goes down again and shuts off. If you bypass the low pressure switch chances are you are low enough on freon you will cause damage to the compressor ($700-$1000 to replace) On the other unit it is not uncommon for the low voltage coil on the contactor to hum. When the unit starts the compressor and the condenser fan should both run. Like NUCULAR said if the fan doesn't run, pop off the 2 yellow plugs and fill with machine oil (not WD40). If it is the fan motor sometimes you can start it with a stick or something, this will get you by until the service man can check. If the condenser fan doesn't run the compressor will get hot and cut off. I would ride to Texas today, but the other guy will probably get there before I do. If I didn't understand your post let me know and I'll try again
Link Posted: 7/15/2002 10:00:08 AM EST
JMO, the two air handlers in the attic seem to be running fine. They are Lennox units and the little green light is showing on both, and air is blowing upstairs and down. The upstairs air is warm and the downstairs is cold. The outside compressor units (also Lennox) sit side by side and it's easy to notice the difference in the two if you stand and watch and listen. One compressor sits silently until it starts up and runs normally for a few minutes. Then it shuts off and goes silent again. The other compressor emits a low buzz or hum all the time, and occasionally seems to try to start up, but just stalls and stops and goes back to humming. I'm assuming this one is the one for the upstairs. All filter, breakers and switches on everything are good to go, or seem so from an eyeball reading.
Link Posted: 7/15/2002 10:24:34 AM EST
[Last Edit: 7/15/2002 10:26:54 AM EST by JMO]
OK I misunderstood. IF the unit outside (condenser) runs for a few seconds and stops then repeats then it is the low pressure switch. What you are seeing is the 1 unit (condenser) running for a few MINUTES then shutting off (cycling off) for a few minutes and this is normal. On the non running unit POSSIBLY, POSSIBLY the points (contactor) is burnt or has ants. Take the cover off and look where the 230volt wires are connected to a relay looking device. This breaks the voltage so the unit doesn't run all the time. IF there are ants or the relay points look burnt, there are 2 smaller wires (low voltage) that send a signal to engage the relay/contactor. Set the t-stat as if you wanted the unit to run. Using insulated needle nosed pliers pull one of the SMALL wires off and rat a tat tat it on the terminal it came off of. IF you have the correct SMALL wire the relay will go full auto, but that is OK. SOMETIMES it will clear enough trash off of the points to buy you a day or two. try that and let me know IF you want to e-mail me I'll give you my phone # and you can call later and I'll walk you through it
Link Posted: 7/15/2002 11:39:39 AM EST
Turn off you downstairs air conditioner and turn the upstairs on to make sure you are looking at the right one. If the fan doesn't come on then see if it spins. Also there is a capacitor that is needed to kick off the fan and the compressor inside. That has blown on mine and just took a couple min to replace. It died on the previous owner too because it was a replacement when I took it apart. It also could just be low on freon, but I would think it would not even bother trying to start, but JMO sounds like he knows better.
Link Posted: 7/15/2002 11:51:45 AM EST
Originally Posted By Jarhead_22: The other compressor emits a low buzz or hum all the time, and occasionally seems to try to start up, but just stalls and stops and goes back to humming. I'm assuming this one is the one for the upstairs.
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JMO, I would shut off the breaker to this unit, it sounds like to me, that the compressor motor is frozen. Could possibly represent a fire hazard (If I recall correctly, the fire at Oly Arms was started by a fan that had frozen and finally overheated enough to start a fire)
Link Posted: 7/15/2002 1:48:39 PM EST
[Last Edit: 7/15/2002 1:49:51 PM EST by Arock]
With the storms we've had the last several days your compressor could be overheated. My compressor has an internal thermal protect switch. Try turning that whole system off and let it sit for 30-45 minutes then turn it back on. My upstairs unit did this last Friday and all it took was turning it off to let the compressor cool down before I turned it back on. One thing I have done before is to spray a garden hose on the compressor to cool it off. On a REALLY HOT day if you let water run slowly over the compressor you will be surprised how much cooler the outlet air is.
Link Posted: 7/15/2002 2:03:13 PM EST
Thanks for all your suggestions, gents. I have no experience in working on A/C compressor units, and don't even know how to get the case off to look at the fan and other parts. I turned off the breaker earlier today and let the offending compressor for the upstairs just sit. I tried turning it back on a few minutes ago and it just buzzed again, quietly, then louder, then quietly again, alternating. I turned it back off and will have to wait until Wednesday until I can get someone out here to look at it. Which reminds me: does anyone want to buy a kidney? In good shape, hardly used, blood type A Pos.
Link Posted: 7/15/2002 2:08:27 PM EST
Originally Posted By Jarhead_22: Any suggestions, aside from "sleep on the sofa?"
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ummm...., sleep on the sofa with a nice comforter?
Link Posted: 7/15/2002 2:25:26 PM EST
Originally Posted By redray: ummm...., sleep on the sofa with a nice comforter?
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Now, why didn't I think of that? Seriously, there are about thirty or forty hex-head screws on the outside of the compressor unit case, and I am hesitant to just start spinning them out. I guess I was hoping for some easily handled temporary problem, but it doesn't look like that's the case.
Link Posted: 7/15/2002 2:35:43 PM EST
sounds like one is cycling on high or low pressure switch and the other has a bad run capicitor , open the panel and there should be a silver oval or round cylinder , if it is swelled upb on top or the sides it is dissconnected internal , get a new one at a motor shop for around 15 bucks , the other one that is shutting off after a few min , hold the small copper line leasving the condenser and see if it is real hot if it is clean your condenser
Link Posted: 7/15/2002 2:44:20 PM EST
Originally Posted By Jarhead_22: I've got a two-story house with a separate A/C unit for each floor. The upstairs A/C has gone down and it's 87 degrees upstairs with the vents blowing warm air. This started yesterday. I changed out the air filters in the blower units up in the attic, but that did nothing for the problem. I checked all the breakers and switches, and all are good to go.
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A failure to blow cold air is always going to indicate a problem with the outside unit, and most likely involving the compressor.
When I went outside to the compressor units on the side of the house, one of them turned on, ran for a while, then turned off again, and was completely quiet while it was off. The other one would seem like it was going to turn on --would start to wind up-- then just stop, but the whole time gives off a low hum or buzz. When I called for service, I was told that no one can be out here until the day after tomorrow. Any suggestions, aside from "sleep on the sofa?"
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First thing I'd check is do a visual inspection of the wiring to and from the compressor. Check for any burnt wires and such and make sure everything is grounded properly. If those are good, I'd do a visual inspection of the capacitor used to start the compressor by looking for obvious signs of failure, specifically charring. If the capacitor has failed, you can pick up another one from most electrical supply places. It's also likely that your compressor motor may have failed. Either way, if possible, remove power from that unit. If the compressor has failed, it's possible that the freon inside could be rendered useless by the unit trying to come on. It was explained to me by the service man that works for my step-father, so I'm assuming he wasn't bs'ing me. Either way, if the compressor is screwed, you don't want it to keep trying to kick on. Also, be sure to turn off the power to the unit before taking off any panels looking for damage. Better to notice any exposed wires and such before turning power back on than to find them taking it apart with juice being supplied to the unit. Remember the Alamo, and God Bless Texas...
Link Posted: 7/15/2002 2:50:39 PM EST
Originally Posted By Jarhead_22: Seriously, there are about thirty or forty hex-head screws on the outside of the compressor unit case, and I am hesitant to just start spinning them out. I guess I was hoping for some easily handled temporary problem, but it doesn't look like that's the case.
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It's been a while since I apprenticed with my father, but what I remember of removing the appropriate screws was there should be some sort of obvious panel area that covers the compressor area, and should be secured with 6-8 screws. Removing those should give you access to all the relevant wiring you'd need without removing the whole exterior. Then again, it's been over 10 years since I worked on an A/C unit, and I was 14 at the time, so things may have changed. Remember the Alamo, and God Bless Texas...
Link Posted: 7/15/2002 3:03:38 PM EST
GodBlessTexas, You are correct, Sir. I got the electrical access panel off and can see all the electrical connections. All connections look secure, and there is no obvious damage to anything. There's something that looks a lot like an ignition coil mounted inside and a block with the power and ground connections. In this block is some type of plunger connector to connect power to the wiring that goes inside the unit. The contacts of this plunger connector look a little discolored, but I don't know how I'd burnish them if that's what is causing my trouble.
Link Posted: 7/15/2002 3:39:08 PM EST
Originally Posted By Jarhead_22: Which reminds me: does anyone want to buy a kidney? In good shape, hardly used, blood type A Pos.
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How much for the kidney? TheRedGoat
Link Posted: 7/15/2002 3:40:16 PM EST
Originally Posted By RJSMITH: sounds like one is cycling on high or low pressure switch and the other has a bad run capicitor , open the panel and there should be a silver oval or round cylinder , if it is swelled upb on top or the sides it is dissconnected internal , get a new one at a motor shop for around 15 bucks
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Found the cylinder, but it looks fine. No swelling, no burnt connectors.
the other one that is shutting off after a few min , hold the small copper line leasving the condenser and see if it is real hot if it is clean your condenser
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I meant that the other compressor unit was running normally: off for a while, then turning on and running for a while, turned on and off by the thermostat.
Link Posted: 7/15/2002 3:41:28 PM EST
Originally Posted By TheRedGoat: How much for the kidney?
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Make me an offer.
Link Posted: 7/15/2002 3:43:50 PM EST
This sounds like diffently a bad start/run capacitor. It doesn't have to be swelled up to be bad. Look at the label on the capacitor it will says something like 35uf 5 440 They run about 10.00 bucks. I've fixed several that had the same symptoms as you have described. Turn off the main breaker and give the compressor a few hours to cool. Now very important...make sure the electric is off. now check again. I hate electricity. To discharge the capacitor take a screwdriver and touch two of the connectors together. Get the new capacitor first to make sure you hook up the same wires. The capacitors are marked on top. F = fan H = herm C = commom If the unit is not freezing up its brobably not low on freon. The larger cooper line will freeze. Any other questions just ask. Rick
Link Posted: 7/15/2002 3:48:16 PM EST
Check your starter capacitor, it is a small silver can with a couple of terminals on the top and will be in line with one of the power connections to the motor. This helps the motor kick over and when it goes out it will seem like the motor can't quite get up enough steam to run. If you have access to an ohmmeter you can check it, you should max out the meter and then it will gradually drop down as the capacitor charges up. The last time my AC went I was at work and the wife called in a service man, he told her we needed a new motor ($540) but recommended an entire new unit($3600). Needless to say after replacing the cap($4.65) the thing took off and has run fine for the past year. Kind of makes you wonder how many of the new units the neighbors have put in were really necessary.
Link Posted: 7/15/2002 3:55:35 PM EST
Originally Posted By Jarhead_22:
Originally Posted By TheRedGoat: How much for the kidney?
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Make me an offer.
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I've got 37.50 in cash in my hand. How close are we? BTW, I have A/C at my place, if you need a nice, cool place to sleep, feel free. TheRedGoat
Link Posted: 7/15/2002 4:01:00 PM EST
Okay, I loosened the bracket and turned the cap around so I could read what's printed on the side. Among a bunch of long meaningless numbers are the following: York: a brand name? 40/7.5MFD: Is MFD some kind of different way to say Microfarads? 370VAC 50-60HZ And I did find the "fan" "herm" and "com" connections labeled. Does that sound like a commonly available cap?
Link Posted: 7/15/2002 4:04:17 PM EST
Originally Posted By TheRedGoat: I've got 37.50 in cash in my hand. How close are we?
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Throw in a couple hundred rounds of recent vintage Lake City .223 and we're getting there.
BTW, I have A/C at my place, if you need a nice, cool place to sleep, feel free. TheRedGoat
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Thanks for the offer. We're "camping out" downstairs.
Link Posted: 7/15/2002 4:10:09 PM EST
40/7.5MFD: Is MFD some kind of different way to say Microfarads? 370VAC 50-60HZ And I did find the "fan" "herm" and "com" connections labeled. Does that sound like a commonly available cap?
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What you need is called a split capacitor. Basically two capacitors in one unit. Its a standard size. If you find one thats marked 40/7.5 440 it will still work just fine. You just can't go under the 370v BTW...how old is the condensing unit? Rick
Link Posted: 7/15/2002 4:15:00 PM EST
Originally Posted By ARs4EVER: What you need is called a split capacitor. Basically two capacitors in one unit. Its a standard size. If you find one thats marked 40/7.5 440 it will still work just fine. You just can't go under the 370v
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Kickass. Thanks.
BTW...how old is the condensing unit?
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The house is two and a half years old.
Link Posted: 7/15/2002 4:44:59 PM EST
A suggestion - you mentioned that you had two outside units. The consensus seems to be that the capacitor might be bad. If the outdoor units are identical (check specs on the capacitors themselves too), you could try swapping the cap from the assumed good unit to the bad one to see if that's what's causing the problem. I don't know anything about A/C, but would imagine that the downside would be the possibility of somehow damaging the working cap, resulting in zero A/C. Sounds like replacements are relatively cheap, however. Someone else will have to address any other potential technical issues (someone mentioned possibly nuking the freon, etc.). Anyway remember that this advice is worth what ya' paid for it (in other words, if you blow both compressors, better get ready to part with the other kidney).
Link Posted: 7/15/2002 8:35:10 PM EST
[Last Edit: 7/15/2002 8:38:42 PM EST by bobbyjack]
That funny looking box with the plunger looking thingy is your contacter points. they are feed from your external diconect box (the one with the fuses in it) through a wire pig pigtail straight to your contactors. The contacters have a plastic tee shaped handle that you can push in with a peice of wood or something that will not conduct elec,the unit will come on,but if the run-capacitor is bad it will kick it right back out again. If the contactor points are black,or burnt out then the contactor is bad. These are not real expensive,but the service tech will put it to you! Edited to say if you are going to mess with the unit with the side cover off,and your hands on anything you are changing out pull the outside disconnect! Killing the juice to the unit. Bob
Link Posted: 7/15/2002 9:06:01 PM EST
I see from re-reading your posts that the contactor points were blueish in color,this is nornal as there is 220 coming through them. Probably just a #357 run capaciter,usally if the filter is realy dirty the unit will just run really long times with out getting very cool,as there is not enough air flow across the evaporator. Usually it will freeze up and you will see ice on the suction line where it feeds the evaporator coil. Generaly speaking if you are low on freion the freezing will be on the other end,down by your condensing unit,your suction line(the bigger of the two lines coming out of your compressor)will have iced up. Good luck Bob [8D]
Link Posted: 7/15/2002 10:04:09 PM EST
Link Posted: 7/16/2002 4:21:36 AM EST
Well, the unit in question kept the upstairs nice and cool until two days ago when it suddenly went TU, so that indicates to me that the freon is fine, unless it all leaked out at once. Does that sound logical? Should I call electrical supply places to find the run capacitor, or should I go to an A/C supply place for it? There's a place that sells A/C stuff not too far from me. It's where I got the frickin' high dollar filters I need for my blower units.
Link Posted: 7/16/2002 5:11:14 AM EST
That is pretty much what I did. I called the A/C shop that normally services my type of A/C unit and the guys were nice enough not only to tell me what I was looking at, but how to wire it properly when I was done. One guy even sat down with me on a break and drew out wiring diagrams to explain what was going on and why it was wired like it was when I found it. The dual caps were a little more expensive, instead of 10 bucks they were like 35 or so.I forget the name of the place, but they were the only carrier fixer in Mckinney.
Link Posted: 7/16/2002 5:20:52 AM EST
If all this doesn't work, just take the AR and blow several holes in your roof and walls- instant fresh air! It could get expensive though, depending on how much ammo you have to use. Good luck with the repairs and don't fry your ass!
Link Posted: 7/16/2002 5:38:47 AM EST
What about discharging the old cap before I swap it out? Do I disconnect the leads (after labeling them, of course [:D]), then short two contacts together with a screwdriver blade? Which two contacts of the three, or doesn't it matter? I'm heading out now to the A/C supply joint in Plano. Back in a few.
Link Posted: 7/16/2002 6:43:52 AM EST
If it's anything like the movies, it's always the white wire...
Link Posted: 7/16/2002 6:50:43 AM EST
I got the cap, or at least I think I do. They acted like they had never seen what I was asking for before, but they dug out a 440/40/7.5 cap for me instead of the 370. I'm just hoping that the larger 440 will fit inside the case. Oh, and it was $67.83 before tax.
Link Posted: 7/16/2002 7:01:24 AM EST
REMEMBER TO SECURE THE POWER!!!
Link Posted: 7/16/2002 7:01:50 AM EST
Does it matter which two contacts I short together on the old capacitor?
Link Posted: 7/16/2002 7:03:45 AM EST
Originally Posted By LWilde: REMEMBER TO SECURE THE POWER!!!
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Absolutely, but thanks for the reminder. The thermostat is off. The circuit breaker in the garage is off. The breaker in the box mounted on the wall above the compressor unit is off.
Link Posted: 7/16/2002 11:15:43 AM EST
[b][size=6][red]S[/red][green]U[/green][blue]C[/blue][yellow]C[/yellow][red]E[/red][green]S[/green][blue]S[/blue][yellow]!!!![/yellow][/size=6][/b] Nice chilly air is coming out of my upstairs vents, thanks to you gents! I had to fabricate a new capacitor bracket out of some sheet metal since the 440 is fatter than the 370, but we are in there like swimwear, kiddies!!
Link Posted: 7/16/2002 12:55:44 PM EST
Link Posted: 7/16/2002 5:38:03 PM EST
Glad it worked out OK. Not to rain on the p-rade, but is the blown cap a symptom of a bigger problem, or just an isolated issue? In other words, is something else wrong with the A/C that caused the original cap to die (and will have the same result on the new one)?
Link Posted: 7/16/2002 6:03:33 PM EST
Originally Posted By bjg: Glad it worked out OK. Not to rain on the p-rade, but is the blown cap a symptom of a bigger problem, or just an isolated issue? In other words, is something else wrong with the A/C that caused the original cap to die (and will have the same result on the new one)?
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Not really..capacitors are really sensative to voltage spikes, lightning, possible a loose wire somewhere. 68.00 for a capacitor??? where did you buy that? They should run 10 to 25.00. Besides the servive call would have been 65.00 and they would charged you 75.00 for the capacitor. Anyway I'm glad its working for you. Rick
Link Posted: 7/16/2002 6:31:24 PM EST
With the storms we've had the last few days a lightning strike is a good possibility. Hit on a service line or just a rising ground potential can fry a cap. Any other electrical anomalies in the house this week??
Link Posted: 7/16/2002 6:48:03 PM EST
Run capacitor failures fall into the "Shit happens" category mostly. Lightning CAN fry almost anything. No unit defect is likely to do this. Price is not that far off for a dual cap and a 440volt. Add a little because you are not a contractor so I think that is close. Don't forget to call and cancel your service call. Polite thing to do and many companies will charge you (me included!!) if you fail to cancel.
Link Posted: 7/16/2002 9:52:18 PM EST
Link Posted: 7/17/2002 2:35:30 AM EST
Hey doc, I really like that sig line!! That arrow story is a good one!! I do boiler work. Every winter, callers either have new baby or "gramps" just came home from the resthome. One gets me up about midnite cause they are freezing. Ask if they have any aux heat - no. When I get to the place and they open door the heat is like a wall - from the woodstove! I just spun around and went home. Let somebody else fix that one!
Link Posted: 7/17/2002 4:16:43 AM EST
The service call was cancelled when the chillinator came back in service, but thanks for the heads up.
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