Air Conditioning - Carrier AC problem - fan stops, compressor doesn't
Doityourself.com community forum was created to provide answers to all questions related to home improvement and home repair. Doityourself community can help you find information about how-to topics on small fixes to large remodeling projects. With comprehensive how-to content and expertly moderated community forums DoItYourself.com makes it easy to tackle even the most complex home improvement projects.View Full Version : Carrier AC problem - fan stops, compressor doesn't
MikeArcher
09-05-05, 06:50 PM
I am brand new here, but in looking at some of the questions, it seems like there is some good advice being handed out. That said, here is my problem that hopefully someone can point in the right direction on.
Approximately 10 year old Carrier unit was not cooling properly about a month and a half ago. Tech came out, diagnosis was small freon leak. Tech added freon, system seemed to work fine, though he did not attempt to find the actual leak. A week ago, unit wasn't cooling well again. A friend of mine that works on ACs on the side took a look, and noticed the compressor fan was not running while the compressor was on. After some additional diagnosis, we have replaced the contactor, the capacitor, and the compressor fan motor. Here are the problems/symptoms. If anyone cares to point me in a direction, I'll happily start down that trail.
1) There still seems to be a freon leak somewhere, as we had to add additional freon after fully charging the system less than a week ago.
2) Even with full freon, the temperature differential does not seem to be great enough between the ambient temperature in the house, and the air coming out of the AC. The air temperature at the vent was measured at around 61-62 degrees, and the temperature in the hourse per the thermostat was 78-79 degrees - giving only a 17 degree differential best case.
3) The low pressure gauge showed 68 psi, which I believe is dead on, but the high side showed 250 when we expected 260 or so.
4) This is the strangest part of all, at least to me since I know nothing about AC equipment. After the system has been on for a couple of hours straight (which makes me question its ability to cool the house in general), it kicks off once the sun starts to go down and the temperatures drop, and it finally makes the goal temperature inside. When it kicks back on again, the compressor fan does not kick on. The compressor is definitely on, as I can hear it kick on, and the whole unit very quickly gets exteremely hot. If I shut the whole thing off, let it sit for probably 5-15 minutes, I can restart it and everything seems to be fine.
So I am somewhat at a loss here as to which of the above information snippets are symptoms, causes, or whatever. I know that without the fan, the compressor will burn up pretty quickly. I just don't understand why the fan won't turn on when it essentially has a direct connection to the power. My only guess is that perhaps the compressor is sucking up all the power due to some other problem, and therefore the fan motor can't get enough juice to power up.
Hopefully some of this made sense to someone who knows a lot more about this than I do, and you can give me some idea what the root cause is for all this, or at least where to look. I would hate to just replace the whole outside unit only to find out the condensor up in the attic had a freon leak, or something along those lines.
Thanks,
Mike
Approximately 10 year old Carrier unit was not cooling properly about a month and a half ago. Tech came out, diagnosis was small freon leak. Tech added freon, system seemed to work fine, though he did not attempt to find the actual leak. A week ago, unit wasn't cooling well again. A friend of mine that works on ACs on the side took a look, and noticed the compressor fan was not running while the compressor was on. After some additional diagnosis, we have replaced the contactor, the capacitor, and the compressor fan motor. Here are the problems/symptoms. If anyone cares to point me in a direction, I'll happily start down that trail.
1) There still seems to be a freon leak somewhere, as we had to add additional freon after fully charging the system less than a week ago.
2) Even with full freon, the temperature differential does not seem to be great enough between the ambient temperature in the house, and the air coming out of the AC. The air temperature at the vent was measured at around 61-62 degrees, and the temperature in the hourse per the thermostat was 78-79 degrees - giving only a 17 degree differential best case.
3) The low pressure gauge showed 68 psi, which I believe is dead on, but the high side showed 250 when we expected 260 or so.
4) This is the strangest part of all, at least to me since I know nothing about AC equipment. After the system has been on for a couple of hours straight (which makes me question its ability to cool the house in general), it kicks off once the sun starts to go down and the temperatures drop, and it finally makes the goal temperature inside. When it kicks back on again, the compressor fan does not kick on. The compressor is definitely on, as I can hear it kick on, and the whole unit very quickly gets exteremely hot. If I shut the whole thing off, let it sit for probably 5-15 minutes, I can restart it and everything seems to be fine.
So I am somewhat at a loss here as to which of the above information snippets are symptoms, causes, or whatever. I know that without the fan, the compressor will burn up pretty quickly. I just don't understand why the fan won't turn on when it essentially has a direct connection to the power. My only guess is that perhaps the compressor is sucking up all the power due to some other problem, and therefore the fan motor can't get enough juice to power up.
Hopefully some of this made sense to someone who knows a lot more about this than I do, and you can give me some idea what the root cause is for all this, or at least where to look. I would hate to just replace the whole outside unit only to find out the condensor up in the attic had a freon leak, or something along those lines.
Thanks,
Mike
Jay11J
09-05-05, 08:48 PM
How old is the new fan?
Is the capacitor a matching rating to the fan motor?
If the fan is trying to run, did you take a stick and try to give it a push to start?
As for temp drop, 17 sounds good.. Take a temp reading before the blower, and just after the coil.. Ideal drop should be around 17 to 20 degree.
Is the capacitor a matching rating to the fan motor?
If the fan is trying to run, did you take a stick and try to give it a push to start?
As for temp drop, 17 sounds good.. Take a temp reading before the blower, and just after the coil.. Ideal drop should be around 17 to 20 degree.
MikeArcher
09-05-05, 09:49 PM
How old is the new fan? Is the capacitor a matching rating to the fan motor?
We just replaced the fan motor a few days ago. We took in the old motor and capacitor to get matches from the local Carrier supply store.
If the fan is trying to run, did you take a stick and try to give it a push to start?
I don't think it is really trying to run, though I did give it a push and nothing happened. Again, after cutting power to the unit for a little bit and turning it back on, it works like a champ every time. There is just some threshold after it cuts off that if it trys to turn back on again, it doesn't work. I have very limited knowledge in the area, but it would seem reasonable to me that the compressor would have to be taking all the juice out of the system, since the fan and the compressor are essentially competing for the same energy, correct? This is just my uneducated guess.
Mike
We just replaced the fan motor a few days ago. We took in the old motor and capacitor to get matches from the local Carrier supply store.
If the fan is trying to run, did you take a stick and try to give it a push to start?
I don't think it is really trying to run, though I did give it a push and nothing happened. Again, after cutting power to the unit for a little bit and turning it back on, it works like a champ every time. There is just some threshold after it cuts off that if it trys to turn back on again, it doesn't work. I have very limited knowledge in the area, but it would seem reasonable to me that the compressor would have to be taking all the juice out of the system, since the fan and the compressor are essentially competing for the same energy, correct? This is just my uneducated guess.
Mike
DNT1
09-08-05, 07:10 PM
Go back and double check your wiring connections on the new fan motor and capacitor I suspect a loose connection, if all is Ok there you simply bought either a bad fan motor or capacitor, replace them. If you have access to a amp probe check the amp draw on the new motor and if you have access to a capacitor tester (like a Fluke 16) test the new capacitor I have seen brand new capacitors way out of range of the stated capacity. Check the simple stuff first (I would check rotation/part numbers and for correct wiring on the replacement motor) it is not unusual to find a wire connector end nearly burned off on older units, you may just need a new electrical connector! Note: I have seen motors installed and rotation was not checked the motor will overheat if turning in the wrong direction!!! and may not restart unless given plenty of time to cool off and of course will have a very short life LOL Good Luck