Calling all HVAC guys...

russ0943

russ0943

yehaw x10
Joined
Mar 28, 2007
Location
Valdese, NC
The HVAC pump outside my house is new (as in 3 years old) and recently when I cut the AC on it will run for awhile and then make a buzzing sound. The buzzing sound lasts about a second and happens about every minute or so. My lights inside dim when this happens. The air coming out of the vents is not cold either.

I plan to go out and check the motor with a meter. Between windings and winding to ground. I'm not sure what else to check because I don't know whats in there.

Anybody heard of this before? Know what it is? I'll pay somebody to come out here and fix it if it needs charging or something that requires other equipment.

Any help is appreciated.
 
Mine did that too at about 3 years old. Pretty much sounds the same symptoms. To me, it sounded more like a chattering solenoid. It was a bad circuit board.

If it were me, I'd maybe cut it off until you can get it checked out...hate to turn a maybe cheap repair into a major expense.

Bad news for me, that board was out of warranty...they helped out with cost, didn't charge labor, but I was still out about three hundred bucks.
 
Sounds like either the fan motor or the compressor trying to start up then going off on overload. Could be any number of things causing that. Fan could be going bad and compressor getting to hot, compressor contactor, or like was said before, the board. I`ve only assisted with commercial HVAC so I don`t have real experience. Like was said, don`t let it continue doing that.
 
jjwestbrook said:
probably a blown capaciter. i pm'ed you my cell number call me and i can walk you through it.
Click to expand...

x2.. I've been through 2 of those overpriced POS's in the 6 years I've been in my house..
 
I kept my 'bad' board...went over it, nothing bad...figured one of the chips got zapped, we had bad storms the night before.
 
Yep my eats start and run cap 1 each / summer.
I go direct to Trane and buy them over the counter for ~$25 and unplug/plug myself.

Pretty easy to check they will either pop and jizz grease everywhere or get pregnat.
If you look in the control panel you should know if its a cap. pretty easy
 
^^^ yup, when my capacity popped last summer... I was really confused. In that case it just wouldn't get the fan running, I coudl hear the compressor trying to run, buzz, would then overheat, hit it's thremo limit, and shut down.
After about an hour w/ the circuit tester, I called a buddy. He was like, look at the capacitor. Doh! Right there stairing me in the face, the thing looked like Quasi Moto w/ a huge bulge. Massive blindsight to not see that.
Of course mine was a real oddball and couldn't find a local place that would sell me one, so had to call the HVAC guys to source it for me for 2x the price. Grrrr. I know they have to make a living and it's justified, I just like the satisfaction of fixing it myself.
 
I have been doing HVAC for about 10 years. Seen this a thousand times, its the capacitor. Easy to change yourself if you can get a new one(CC Dickson). Just make SURE you disconnect the power first. Sounds like theres a bunch of knowledgeable people on here about this type of thing.
 
Wow. Didn't expect this many posts. Here's an update.

- The start/run capacitor (one single cap on my unit) was not bulging or leaking. Did have a burn/rust mark on the side though. Went to Grainger and got another $15.
- Installed it, wire for wire and when I powered it on it was doing the same exact thing. Then I hear a sizzle and notice a smell coming from the breaker box that is right next to the unit, mounted on the side of my house.
-Cut all the power.
-Opened it up and the connection on the house side of the breaker had burnt up. The wires were fine. This is a 60A box. Went to Lowes, got another. Installed. After installing I noticed that the tag on the outside of the box says "Max Ckt Brk Size 40A".
-Put the old capacitor back in to rule out the fact that the new cap had caused this.
-Powered up, it was doing the same as before. Fan running fine. Compressor buzzing every 20 seconds or so.
-Installed new capacitor back in. Doing the same thing...buzzing.
-Checked voltage at the contactor leads, 120V.
-Powered down. Measured resistance from each lead to ground. No connection/very high resistance. Measured resistance across each lead, they were around 4-8 ohms.
-Powered it back up with fan wire unplugged from control board. Compressor still buzzing.

It is a Weather King 10PJB36A01 made in 12/2004 so hopefully it still has some warranty left on it.

I'm at a loss right now. I'll do everything I can before I have someone come and charge me an arm/leg.
 
Another thought:

The original capacitor in there read 40 +3UF +/-6% 440VAC

The capacitor I got is 40/5 MFD 440VAC

Just double checking that these are the same thing.
 
im a hvac guy when im not wheeling. this should help. if the compressor was running for up to a minuite before shutting down, i would lean toward being low on refrigerant. many a/c units have low pressure switches that cut out when low. at rest, your pressures are equal, but when compressor starts pumping, the low side gets low, while the high side raises. if low side gets too low, switch will cut off the unit. then as the pressures equalize, it will let it come on again. this is a saftey to protect your equipment.
howeavor, since i think you said the compressor wont even come on, just trys, hums, and quits, let me point you in a differant direction. since you know its the compressor, not the fan, double check some stuff and verify. you said your reading 120 volts- most a/c units are 240 volts. make sure youve got a full 240( plus or minus 20%) to the contactor. then make sure you get the same voltage on the other side of the contactor when its pulled in. somtimes ants will get in there and cover the contacts. you should be able to physically see the contacts. if this is the case, or if you dont have but one leg(120 v) sometimes the fan will run but the compressor will try and fail. make sure you have both legs(240v) make sure your getting 240 from the house. thats the easy fix.
if that dosent help, heres the bad news. one of the purposes of the capacitor is to
"jump start " the compressor, because ,like any motor, starting it takes the most effort, and draws the most amps. which is why your lights in the house dim upon startup. if youve got the correct voltage, and a good capacitor, that tells me that the copmpressor is hving trouble getting started. when hvac compressors try and fail, their internal overload- built inside the shell- will trip. these will auto reset when it cools down. thats why you hear it try to start every so often. try a super boost capacitor- a special one to give it a kick in the pants to start.parts houe, ask for a malco superboost #spp6. if it still wont, your compressor is shot, locked up. not repairable. if its under warranty, dont tell the company that you worked on it. even though youve done nothing wrong, some will say youve voided their warranty. heck, if under warranty, let them work on it 4 you.
ps: you have a double capacitor- 40 mfd for the compressor, 3 for the fan. you should be ok there. they just share, instead of having 2 seperate.
 
I guess I just had a brain fart on the voltage measuring thing. I'm getting 240V to the motor when the contactor is pulled in. Just went and double checked.

I'm gonna call a tech out here. I think I've given it a good attempt. Hopefully its under warranty.

Thanks for all your help. If you have any more suggestions before tomorrow, lemme hear them because I'll give anything a shot.
 
Bigjeeprob can verify this if I`m correct.
Turn power off.
There are 3 prongs for the compressor. Run, start, and common. If I remember correctly you should have continuity between all 3 combinations. (this checks the windings of the compressor) If you don`t have continuity between all 3 then you have a bad compressor. You can also check each prong to ground to see if it`s shorted.
Just remember, I`ve only assisted in stuff like this. I`m not a tech by any means. :cool:
 
yeah, 1 -if no continuity between windings, means windingd are open(bad). usually wont even try to start. 2-continuity from any comp terminal to ground= shorted to ground(bad). with this, the fuses blow as soon as compressor trys to start. and 3- good continuity between windings, none to ground, but the compressor trys to start but hums, and then goes off on overload= compressor locked up(bad). sometimes fuses will blow here, too.sometimes you can bump it with a boost capacitor, but the odds are ussually against you.

well, no shame in calling in the contractor, as i think youve made a valiant effort. wish my customers were as sharp as you. then i wouldent go on a million "no a/c" calls just to find dirty filters or the stat turned to "off". good try, man.
 
if you need a good local guy, my associate pastor is an hvac guy. (allstate mechanical) give me a shout if you want his number.
 
bigjeeprob said:
3- good continuity between windings, none to ground, but the compressor trys to start but hums, and then goes off on overload= compressor locked up(bad). sometimes fuses will blow here, too.sometimes you can bump it with a boost capacitor, but the odds are ussually against you.
Click to expand...

I called a reputable guy referred to me by some of the industrial service guys at work. He told me to get a hard start cap and to try that. If that doesn't work he said he'd come out and take care of it for me.

I tried the hard start cap and it just buzzes louder...ha. No start. So the compressor is locked up. He said it was more than likely under warranty. Standard warranty is 5yrs on Weather Kings.

Thanks for all your help. I'll update once I get it up and going. Its hot as crap in the house. Crack'n the windows tonight again. :kaioken:
 
96tacolx said:
Bigjeeprob can verify this if I`m correct.
Turn power off.
There are 3 prongs for the compressor. Run, start, and common. If I remember correctly you should have continuity between all 3 combinations. (this checks the windings of the compressor) If you don`t have continuity between all 3 then you have a bad compressor. You can also check each prong to ground to see if it`s shorted.
Just remember, I`ve only assisted in stuff like this. I`m not a tech by any means. :cool:
Click to expand...

I posted this earlier:
-Powered down. Measured resistance from each lead to ground. No connection/very high resistance. Measured resistance across each lead, they were around 4-8 ohms.

Shows good, probably just locked up
 
Had a guy come look at it. The compressor is locked. Its under warranty but is still going to cost me $600 to get it replaced. This sound about right? Know anyone who will do it cheaper?
 
thats not totally unreasonable considering the time of the year. everybody is busy , they dont have to cut prices right now . i assume he is picking up the comp. and returning the old one for credit. my company charges $75 just for handling the warranty paperwork and returning the part. it would prob. be around 1200-1400 if it wasnt under warranty.
 
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