Noisy condenser motor
#1
08-02-15, 02:56 PM
Join Date: Aug 2015
Posts: 7
Upvotes: 0
Received 0 Upvotes
on
0 Posts
Noisy condenser motor
So back in June my wife had a local hvac contractor come out to look at our unit, which wasn't blowing cold air(turned out to be a bad capacitor). The contractor replaced the original cap (370v 45uf 5uf) with a 440v 40uf 5uf. About three weeks later the condenser motor started making strange noises (mostly at startup, sometimes randomly) that almost sound like an electric short alternating from high to low pitch.
We called out a different contractor to take a look at it and he's telling us the first guy should've never replaced the capacitor with the lower mfd rating and he can't say whether or not it caused the noise problem but there is definitely something wrong. So there are actually two questions that I have, first is that a legitimate practice to replace caps with lower mfd rating and second is the theory on what may be causing the noise (below).
The second guy says he believes the noise may be coming from either low or high freon. If it's low he says we'll need a new coil, a $2500 repair, if it's high than it's a bad txv, a $600 repair.
Any insight from anyone is appreciated
We called out a different contractor to take a look at it and he's telling us the first guy should've never replaced the capacitor with the lower mfd rating and he can't say whether or not it caused the noise problem but there is definitely something wrong. So there are actually two questions that I have, first is that a legitimate practice to replace caps with lower mfd rating and second is the theory on what may be causing the noise (below).
The second guy says he believes the noise may be coming from either low or high freon. If it's low he says we'll need a new coil, a $2500 repair, if it's high than it's a bad txv, a $600 repair.
Any insight from anyone is appreciated
#2
08-02-15, 03:03 PM
Member
I agree that the first tech shouldn't have replaced the capacitor with one of a different value (higher voltage rating is OK, but capacitance value should be the same). Are you sure the noise is coming from the condenser fan? The reason I ask, is because although the capacitor is the incorrect size, it's the compressor side that's wrong. You have what is called a dual capacitor, two capacitors in one housing. The 45uf side is for the compressor, while the 5uf side is for the condenser fan. I'm not an HVAC tech, so I can't comment on the refrigerant charge. I would suggest that you replace the capacitor with the correct value. I would hate to see you possibly damage your compressor because of the capacitor being the wrong value. You can change the cap yourself, and it's relatively inexpensive.
#3
08-02-15, 03:26 PM
Join Date: Aug 2015
Posts: 7
Upvotes: 0
Received 0 Upvotes
on
0 Posts
I'm no hvac tech myself so forgive my ignorance on the matter. The second tech replaced the cap with the correct one so that should be good although the unit was running for 5 or 6 weeks with the incorrect one. I believe you're right though, the larger motor inside the unit is where the noise is coming from what I can tell anyway.
#4
08-02-15, 04:00 PM
The onfo the second tech told you is a lot of BS. Did he even take pressure reading's on the unit?
#5
08-02-15, 04:19 PM
Join Date: Aug 2015
Posts: 7
Upvotes: 0
Received 0 Upvotes
on
0 Posts
No he didn't take any pressure readings. He said he was going to coming back Wednesday morning and drain/weigh all the freon to determine what the problem may be.
#6
08-02-15, 04:21 PM
Group Moderator
The second guy says he believes the noise may be coming from either low or high freon. If it's low he says we'll need a new coil, a $2500 repair, if it's high than it's a bad txv, a $600 repair.
It sounds to me like you need a condensor fan motor. Did the tech disconnect it to see if the compressor was noisy ?
How old is this unit ?
#7
08-02-15, 04:26 PM
I hope you cancel that appointment. Don't let him do that. That is not the way to figure out if the unit has enough Freon. Obviously he doesn't know what subcooling is.
Last edited by skaggsje; 08-02-15 at 04:28 PM. Reason: correction
#8
08-02-15, 04:31 PM
Join Date: Aug 2015
Posts: 7
Upvotes: 0
Received 0 Upvotes
on
0 Posts
No he didn't disconnect anything that I'm aware of other than when he swapped out the capacitor. The entire system is 2009
#9
08-02-15, 04:36 PM
Join Date: Aug 2015
Posts: 7
Upvotes: 0
Received 0 Upvotes
on
0 Posts
It's starting to look like I will be. He said if the txv was bad you wouldn't be able to get an accurate reading that was the reason for him to drain everything. And that if he was going to drain everything he wanted us to commit to fixing whatever the problem was the same day...
#10
08-02-15, 04:44 PM
I have a feeling he setting you up for a very large bill. You don't need to remove the freon to determine if the TXV is working. Just put gage's on and read the pressure and get the temperture of the pipe. About 10 mins. What he's doing could take 2-3 hours.
#11
08-02-15, 05:22 PM
Join Date: Aug 2015
Posts: 7
Upvotes: 0
Received 0 Upvotes
on
0 Posts
So I disconnected the condensor fan motor and it's definitely coming from the compressor motor. Is there a chance that having the wrong capacitor in there created this problem?
#12
08-02-15, 06:02 PM
Don't never let this guy touch your AC. What a big BS. It is shame that we have this type AC tech around, If I were you I double check to see if the capacitor he installed for you has the right size. At this time, the compressor may be bad already(whatever the reason), but since it is only 6 years old, do you have warranty for the unit? Anyway, Cancel Wednesday's appointment, call another tech.
#13
08-02-15, 06:11 PM
Join Date: Aug 2015
Posts: 7
Upvotes: 0
Received 0 Upvotes
on
0 Posts
I did take a look at them. Previously there was only one, now there are two - a 40 5 that he said he could wire to make a 45 and a separate 5.
We did cancel Wednesdays appoitment and it's really a bummer that between the two of these guys I've spent over $500 and still no fix.
We did cancel Wednesdays appoitment and it's really a bummer that between the two of these guys I've spent over $500 and still no fix.
#14
08-02-15, 09:13 PM
I have never heard people wire a 40 to 45 capacitor. Did he really replace the capacitor for you ? A capacitor is only cost $20-30, should just put a 45 in there and be done with it. You need to put a 45 in there and let's hope that is all the problem.
