Whats your opinion - http://www.hvacmechanic.com/ Forums
Original message
| unkyjoe
 |  "Whats your opinion"
, posted Fri 23 May 19:14  
OK here goes.
Ten year old Goodman 4 ton ac with Intertherm air handler.
Compressor blew 6 years ago and was replaced under warranty.
Last year condensor motor blew and was replaced with 1/3hp instead of 1/4hp motor same RPM's, goodman says this is ok?
This year, I had the evap coil which is exposed and sitting on top of air handler removed and acid washed and clean by a licensed A/C tech. Placed the coil back into the unit, replaced the piston on the metering device.
Freon was captured into the condensor while this work was performed, acid washed the outdoor condensing unit as well.
Tech pulled a vacumn for about 30 minutes then setup his gauges and charged via superheat method.
This is the problem, suction side is ok, within norms, high side climbs to 300psi and stays there.
Evap coil temps top of coil 77 middle of coil 58 bottom of coil 44.
Where the high side meets the metering device the temp is 130, the temp of the air out of the vents is 62, outside temp is 97 with humidity around 50%.
A/C Tech is a trusted family friend, he is telling me he thinks there is an obstruction inside of the evap and recommends replacing the evap coil.
What do you guys think, If I do replace it I am going to replace the entire air handler with a new 13 seer coil to prepare for 2010 freon switch and new condensor.
I need your expert opinions as to what else this might be.
Thanks in advance.
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Replies:
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| theduke03
| "Re(1):Whats your opinion" , posted Fri 23 May 19:24:
Your tech is mistaken. There is no obstruction, that would not cause these temps. I believe your problem is (assuming outdoor coil is clean) Non condensibles in system. Did he use a micron gage when he pulled the vaccum? If not then there is no way to verify the absence of non condensibles. I think he got water in the coil.
Unless... Did unit work well after the condenser fan was replaced? Are fan blades rotating in correct direction?
I would also like to know what the low side pressure and suction line temp was. I can gather from your coil temps that the low side pressure is about 74 psi, suction line temp 77? If so then that's about 30-35 degrees of superheat which would be too high on a 97 degree day.
If outdoor unit is a Trane or American standard it is possible that it was very dirty and cleaned incorrectly which would have minimal or no effect that a cleaning is supposed to have. So what is the make and model of your outdoor unit?
"My dad was the most feared furnace fighter in Northern Indiana."
[this message was edited by theduke03 on Fri 23 May 19:44] |
| | unkyjoe
| "Re(2):Whats your opinion" , posted Fri 23 May 19:37
Duke, its a Goodman 4 ton CK49-18 and no, the fan motor was replaced with a 1/3 instead of a 1/4hp motor, and I noticed immediatley that the air coming out of the top was less than before, it was coming more out the side of the coil.
The guy working on this unit now kind of inherted this issue as I was not happy with the previous companies work, and since the fan motor was replaced the unit has never cooled properly. Could this be the issue? I mean this is a simple and less costly repair. I just dont buy the coil obstruction answer, I think it is grasping at straws.
Let me say again this unit has not cooled properly since the motor was replaced.
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| | theduke03
| "Re(3):Whats your opinion" , posted Fri 23 May 20:05
That's the info I needed. The size of that motor may be OK, but it's rotating backwards. Air should discharge out the top. How did your techs not notice this? Stop running the unit, this needs to be corrected. Look at new motor for 2 wires(usually purple and yellow but not always) that are connected with a plug in the middle. If it has this plug (most do not have it) you can reverse the plug and reverse the rotation. I think it doesn't have this cuz if it did the original installer would have set this properly but it's worth a look. If possible I will post a picture soon.
"My dad was the most feared furnace fighter in Northern Indiana."
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| | unkyjoe
| "Re(4):Whats your opinion" , posted Fri 23 May 20:12
My AC guy checked it and said it is turning the proper direction, but who can I beleive at this point, I know it does have the purple and yellow wires in addition to two other wires, so post the pic if you can and I will check to make sure.
I know it moved air better than this before it was replaced, always trust your gut feeling on something, I am no AC tech, I did use to work on auto ac years ago and the principal is the same. But if the pressures are off this bad it stands to reason the condensor may be spilling hot air back into the box if the fan speed and rotation are not correct yes?
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| | theduke03
| "Re(5):Whats your opinion" , posted Fri 23 May 20:27:
Ok then. If rotation is correct then it is possible that the fan blades are too low on the shaft causing air to recirculate inside the unit.
Could fan blades be upside down? Should be cup side up.
I,m having problems uploading my pics but I will update this post with the pic in a bit.
"My dad was the most feared furnace fighter in Northern Indiana."
[this message was edited by theduke03 on Fri 23 May 20:30] |
| | unkyjoe
| "Re(6):Whats your opinion" , posted Fri 23 May 20:38
Do you know where I could find information on the distance of the blade on the shaft. If you can please let me know and I will check this out as well. I have a feeling this is the major part of the problem.
Thanks
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| | theduke03
| "Re(7):Whats your opinion" , posted Fri 23 May 21:55
I can't find info on the blades but you can look at your neighbors unit or another one and get an Idea of what the blade height should be in relation to the shroud.
"My dad was the most feared furnace fighter in Northern Indiana."
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| | unkyjoe
| "Re(6):Whats your opinion" , posted Fri 23 May 20:37
Once you post your pics I will have a look.
I am going to pull the lid on this in the AM and take some pics, I can feel air coming out the top of this unit, but like I said, not much and not like before, it is also spilling air out the sides of the unit. On the top edge of the coil and the high side is running about 130 degrees inside, way too hot.
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| | theduke03
| "Re(7):Whats your opinion" , posted Fri 23 May 20:52:
If rotation is incorrect, just pull this plug apart, reverse it, and plug it back together.
Your problem is definately with the airflow thru unit. Will be difficult to pinpoint from here but still possible. Pics will help. Upload them to photobucket.com, then click on img code to copy it, then paste it in your post. These are the most likely causes of your problem:
Incorrect rotation
Fan blades too low/below the shroud
Incorrect rpm
Bad/incorrect capacitor
Fan blades loose on shaft
"My dad was the most feared furnace fighter in Northern Indiana."
[this message was edited by theduke03 on Sat 24 May 07:13] |
| | unkyjoe
| "Re(8):Whats your opinion" , posted Sun 25 May 13:37
Duke, when you say shroud, you mean the top cover of the unit?
This particular model has a one piece top cover with the fan motor mounted via 4 bolts. We did verify the 1/3 hp motor is longer than the 1/4hp and that is what is preventing the fan blades from being mounted far enough up the shaft to move the air effectivly.
However I am concered after replacing the blade back on as to where it should be positioned? I also dont have the old motor from when it was orig replaced to measure this nor to see the proper fan rotation direction. I suppose I can have my tech contact Goodman and find this information out.
Back to the shroud, I was thinking you were refeering to some baffle inside of the unit that would create kind of a venturi effect to route the air up and out of the unit but there is no such thing on this model. Goodman CK49-1B
Thanks again for the help.
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| | theduke03
| "Re(9):Whats your opinion" , posted Mon 26 May 10:28
The shroud is a round collar, usually attached to the underside of the cover. The fan blade sits somewhere within this shroud. I can't say how your blades should be in relation to the shroud but usually the bottom of the shroud opening is about level with the center of the fan blades. If fan blades are under the shroud too far then air will blow around the shroud and recirculate inside the unit instead of blowing up and out. If blades are too low and can't be moved up then you will need a new motor, preferably the correct one.
"My dad was the most feared furnace fighter in Northern Indiana."
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| | yuri
| "Re(3):Whats your opinion" , posted Fri 23 May 19:53
Fan is probably going backwards. Some are reversible if it is a 4 wire type. Apparently some 3 wire type will go backwards and just need the 2 wires reversed on the capacitor. Never seen that myself but a few guys posted that here last Summer.
Yuri
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| | Houston204
| "Re(4):Whats your opinion" , posted Mon 26 May 00:31
Universal motors on 10 seer condensers will create this high head pressure with our Texas heat.
"Tip of the Day" Remember to remove power first.
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| | unkyjoe
| "Re(5):Whats your opinion" , posted Tue 27 May 18:17
Update: Fan motor replaced with 1/4hp motor which was a full 1 inch shorter, as soon as he fired up the system I heard the old familiar sound that it made when it was working properly and it proceeded to push much more air out the top.
Come to find out his temp probe was showing 10 degrees hotter than mine was, so it was hard to do a superheat subcooling, he did add more freon and the evap coil is now sweating all the way to the accumulator on the suction line near the compressor.
Pressures are still off, he got the high side down to about 275 psi, low side around 75psi. The unit is cooling very well, but I still think there is air-moisture in the lineset but could not convince him to pump the system down, I will give it a few days and see how it does. What would you do at this point?
Thanks again for all your help, couldnt have done it without you.
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| | unkyjoe
| "Re(5):Whats your opinion" , posted Tue 27 May 08:56
I am also considering replacing the orrifice tube with a TXV valve on this system to get better performance.
Should I also "remind" the service guy to replace or install a filter-dryer after opening the system, I want to try and get this done right and all at the same time.
Thanks
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| | theduke03
| "Re(6):Whats your opinion" , posted Wed 28 May 00:38
Your tech probably did not get moisture in the system, that was an early guess I made before learning all the facts. He should have replaced/added a filter drier as a matter of standard procedure but you should be ok without it. As for the txv idea I don't see a reason to change to a txv, for the cost and the hassle you will never feel the difference plus you may need starting components added to your compressor. I would like to know why you don't like those pressures? Was it 95 dgrees outside? If so I would run fast and never look back.
"My dad was the most feared furnace fighter in Northern Indiana."
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| | unkyjoe
| "Re(7):Whats your opinion" , posted Wed 28 May 14:27
Do those pressures sound right to you?
I know this, I used to keep the temp at 75 to feel cool, now we are keeping it at 78 and it seems to be very comfortable in the house, I assume this is because it is effectivly removing the humidity from the air.
So far so good, another 95 degree day and the temp in the house is holding at 78 very well.
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| | theduke03
| "Re(8):Whats your opinion" , posted Wed 28 May 18:54
Like I said, If it is 95 degrees out when those pressures were taken I would run fast and never ever look back.
"My dad was the most feared furnace fighter in Northern Indiana."
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