My carrier weathermaker quit working. It is about 14 years old. I went outside and there is a loud hum and the fan is not running. I spun the fan with a screwdriver and it came on, but still barely spun. It did not spin like normal. I pulled the power disconnect and still heard the buzzing. I turned off the thermostat and the buzzing finally stopped. I took the cover off and turned the thermostat back on, the buzzing was coming from a relay. Honeywell DP204DA5003 coil 24v 50 hz
24 v 60 hz.
Am I to assume this relay is bad? I appreciate any help. My family is sweating and tomorrow is a holiday so I am not sure what I am going to do.
I have a small unit to my bonus room. It is a different brand unit. I am not sure if the relay out of there would work or not.
I pulled the power disconnect and still heard the buzzing. I turned off the thermostat and the buzzing finally stopped. I took the cover off and turned the thermostat back on, the buzzing was coming from a relay. Honeywell DP204DA5003 coil 24v 50 hz
24 v 60 hz.
CY: That's normal, to hear the contactor relay buzz.
Am I to assume this relay is bad? I appreciate any help. My family is sweating and tomorrow is a holiday so I am not sure what I am going to do.
CY: More likely that the fan motor dried out. You may be able to pump in some non detergent 20 or 30 weight oil, where the motor shaft comes out, and buy some time. But, it really ought to have that fan replaced. Please don't run the unit with the fan idle, it will over heat and burn out the compressor.
I have a small unit to my bonus room. It is a different brand unit. I am not sure if the relay out of there would work or not.
CY: It's probably not the relay. It's more likely dried fan bearings.
The relay is probably fine, although I don't know how loud this buzzing is. It probably normally is covered up by the hum of the compressor. A likely cause of the failure is the run cap for the fan motor has failed. The compressor has probably shut down either due to a Klixon switch which should reset when it cools, or a high side overpressure switch, which may require a manual reset.
Most units have only a start cap - I replaced mine last week when it died . My unit is about 12-13 yrs old , this is the first service it's needed since the second year of operation . The leak was so small it took a year for enough refrigerant to leak out to be a problem ...
The overwhelming majority of residential AC amd heat pump condensor fan motors are the "PSC" type which have no start capacitor but instead need to have a run capacitor connected at all times.
Perhaps where you live ... I've never seen a PSC motor used for condenser fan duty here , every one I've ever worked on was a cap start induction run motor . Furnace blower motors are often 3 speed units , and they too only have a start cap . Your article also suggests that the PSC motor is speed-variable , and I can see no reason why one would want to vary the speed of a condenser fan ...
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MOST of the high-end, high-efficiency AC units today have variable speed indoor unit fans AND variable speed condensor fans. It's part of the way they manage power use, by varying speed depending upon O.A.T. and load.
But those with truly variable speed aren't usually PSC motors, but 3- phase inverter-driven types. Some of the older ones on the outdoor units, after they started adding the variable speed thing, were multi- winding PSC types.
Either you are confused or you live on a different planet.
To be clear, the 'condensor' is the outside unit.
3 wires, a capacitor and no centrifugal switch =PSC
Here again you are wrong, except in the case of some ancient belt drive furnace units.
. Your article also suggests that the PSC motor is
Where multi speed PSC motors are used for evaporator fans, it is because it is often desirable to run at a higher cfm; for instance whenever auxillary heat is being used.
But I was discussing condensor fans above, which in the vast majority of cases will be the PSC type the exceptions being ultra-high efficiency units and those manufactured after the phase-out of R22
Duh , I dint know that !! You really think I'm stupid ?
And you're *WRONG* . 3 wires and a cap is CSIR - cap start inductive run . My bench mill has 2 caps , a start and a run . My condenser unit has a 5/40 MfD START cap . 5 for the fan , 40 for the compressor unit .
Bullshit again , my 13 year old frnace has the squirrel cage fan mounted on the motor shaft . It has only a start cap ...
Here's one where you might be right - I have no experience with electric aux heaters , always had a gas furnace .
And again I say - I've never seen anything except a single--cap fan motor in a condenser unit . Lloyd S's response made some sense , in that varying speed according to heat/cool load can be a "good thing" .
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Snag,
A motor with a start capacitor also requires a start switch and a start winding (most usually integral in the motor, although hermetic compressors usually have the start switch externally mounted). Most condensor motors aren't so-equipped, because they don't _need_ the starting torque a start winding and capacitor provide.
Most motors that can undergo extreme "slip" on starting are PSC capacitor RUN motors, not cap-start.
Capacitor-start is used (almost solely) when a motor must start under heavy load. A free-wheeling fan nowhere near meets that criterion.
Hmmm , sounds like we might be hung up on terminology , I was taught that was a start cap .OK , poked around a bit , and looks like the only major differences between CSIR's and PSC's is the size of the cap and lack of a centrif switch . So technically he's correct , and I never knew or cared about the difference - hey if the cap goes bad neither one is gonna spin on it's own .
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It is terminology, sure, but there's a _distinct_ difference in the whole philosophy of how a cap-run motor operates from that of cap-start.
In capacitor-start, a separate winding that draws so much current it _may_not_ remain connected for more than a couple of seconds provides very heavy phase-shift relative to the run winding, so the motor starts in a particular direction, and does so very rapidly, with a lot of torque. As soon as it comes up to semi-synchronous speed, the centrifugal switch cuts out the start winding so it doesn't over heat.
In a capacitor-run circuit, there is also a separate winding, but it's sized and has an inductance such that it can remain powered indefinitely. It provides just a _slight_ "kick" in the phase difference between the run and "start" windings, so that the motor starts in the right direction, then SLOWLY spins up to semi-synchronous speed. At that point, the run winding does the heavy lifting, but the "start" winding continues to provide a small impetus; it's effect diminishes as speed increases.
Schematically (as you note), there's very little difference in the circuits, except for the starting switch in the capacitor-start motor. In terms of inductance, power factor and consumption, phase shift in the windings, and starting torque, there is a lot of difference.
Despite this being "just semantics", there's a huge difference in the application range for the two types of motors (and the capacitors are vastly different values between the two types).
True, but a CSIR motor will continue to run just fine if you give it a spin to get it started. A spun-up PSC motor will run poorly without its run cap.
Glad you learned something--I was really beginning to wonder...
Main difference from a user standpoint is that a capacitor start induction run motor ( which has a centrifugal switch ) can start under quite a bit more load as compared to a PSC motor, and a PSC motor is more electrically efficient.
The best of both worlds lies with the capacitor start /capacitor run motor which, in addition to a centrifugal switch, has 2 capacitors--it's fairly common to see this type of motor on air compressors, drill presses and such, the presence of two capacitor "humps" usually being their most distinctive visual feature.
I'm in Virginia, fairly near Washington DC, and my unit (about a fifteen year old Carrier) has a PSC motor. There is no click of a centrifugal switch, and if you try a clamp-on ammeter, you will find current through all three leads some time after it has spun up, and when a cap start would have disconnected it. I believe that the OP stated that his was a Carrier unit too.
The cap is an oil-filled cap (a combination one in a single package, with the other one (much higher capacitance) used to run the motor in the compressor. Cap start motors look similar (though usually have the cap mounted in a bump on the outside of the motor, while the run cap for this PSC is mounted elsewhere on the frame of the system, where it sees less vibration -- especially since it needs to power both motors -- the fan and the compressor.
Mine is three speed, has an oil filled cap, not a standard start cap, and I've had the motor form mine apart -- there is no centrifugal switch. IIRC, the cap connects to one of three input leads, while power and return connect to two others, for five wires total, or sometimes six, if the motor is a four speed one, which works fine even though my system only uses three speeds.
It controls speed by adjusting the torque (which would be the starting torque in a cap start motor), but balancing that torque against the air resistance of running the blower. If it were a cap start, it would keep going up to centrifugal switch speed, losing the extra torque, and dropping back down in speed until the centrifugal switch closed again, repeating the cycle until the start cap gives up (fairly quickly -- I blew one on my lathe with too many starts and stops in a fairly short period. :-)
Perhaps a tradeoff between heat exchange rate and noise level, if people like to sit out on the deck or have a window open while it is running? But it certainly is used to good effect in the furnace/AC blower indoors.
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