Air Conditioning - Condenser Fan Problems

Hello,
I need some expert opinion on the way my condenser fan has been acting up. I have a 14 year old Heil High efficiency 5000 condenser unit. 3 ton. Lately as the unit starts up the fan starts O.K then ubruptly stops. It sounds as if something has manually stopped the fan with a hand. It grumbles. Then it starts to run again. It does this at least three times during the begining of the cooling process. The stopping of the fan coincides with a clicking sound in the unit. Like a contact is being made. Then it seems to run fine, for the rest of the cooling cycle. The house stays cool no problem. the a/c seems to be working fine. It will be 95-100 outside and a cool 71 indoors. I know that the fan is not supposed to be making the noise, and the starting and stopping like it has been doing. Please any suggestions as what is about to go south with this unit? Any help would be welcome.
Thanks.
B

The bearings are worn and the stator has shifted so that the magnetic fields are no longer aligned inside your fan motor. ITS WORN OUT Replace the fan motor and capacitor ASAP

Hello Saturn,
Thanks for the info . I will change out motor and capacitor as soon as possible.

B

Hello again,
Needing some more help. I replaced fan motor,and capacitors.
I have a Heil distributor in town and everything is O.E.M.
Still having the same problem.
Unit starts fine then after about 3 - 5 second The fan ubrubtly stops. makes a sound like BRRRRRRNNNNTTT. Then starts going again. It does this about 4 times at the beginning of the cooling cycle. The A/C cools house fine. The stopping of the fan is not normal. This is the first season that it started making the sound.
Any idea's as what might be causing this?
Compressor?
Swithiches?
Contacts?
Any help would be appreciated Thanks.
B

Is this a heat pump?
Pls post the MFR & M/N of that outdoor unit.

Hello,
No not a heat pump. It is an outside condenser unit, Heil High efficiency 5000. 3 ton unit. 10.5 SEER. 14 years old.
B

High efficiency 5000 is "not" a model number but rather a "marketing name".

There should be a nameplate attached to the outdoor unit with the m/n printed there.

Sorry,
The model # is CA5536VKA1.
Thanks,
B

Sorry about not replying yesterday night. Teaching a couple of kids to ride their bikes (and running behind them for what seemed like an eternity) plus family time later just wiped me out. :p

I think I know what's happening here.

I believe your unit comes loaded with a control called the "Low Ambient Switch (LA)", Heil part # 1059429.

Some of these LA switches have a temperature sensor, some others a pressure sensor. What temperature? what pressure? the one of the refrigerant in the condenser.
For what purpose? to cycle the condenser fan motor ON and OFF, as needed, in order to prevent the P or T from getting too low (which is not good for the system).

On steamy-hot days, a LA switch that is working fine should maintain its contacts "closed", hence the fan will run non-stop. But on those lukewarm or cold days, or during the first few minutes after a call for cooling (when the condensing unit is not yet too hot) the switch's contacts will take turn opening and closing, causing the fan motor to cycle ON and OFF.

How would you know for sure if this is what's happening with your unit?
Well, I believe that condenser fan motor should have "3" wires coming off of it; likely one black, one red and one brown. The brown goes to the capacitor; the red to one of the two hot lines coming off the contactor power leads, and a black wire which prior to going to the other hot line in the contactor, connects to the LA switch.

How can you test if this switch is what is causing the cycling of the fan that is bothering you?
Easy, place a jumper across the black wires that are connected to the two terminals of this switch...the blower should now run non-stop.

But you want this switch there without any jumpers, doing its job, unless it has become defective and just keeps on switching ON and OFF the blower for no good reason (in which case it should be replaced).

If what I've written above is what you have (and you'll tell me later if it is or not), you did not have to buy yourself that new motor. :( Maybe you can return it...but with this unit having been running for 14 years, is good to have a spare.

No problem,
Same here got tied up with the family. I'll try to jump the L.A. switch as soon as I can.(Probably will not be until Monday) The wife and kids got more plans for me tommorow.
I might just replace it and elimate that possibility and take it from there.
Thanks!!!
I really appreciate all your help and ideas. I'll let you know what happens.
B

Agree with p man, it did not hurt anything to replace the 14 year old motor and capacitor it was on its last leg anyway. That low ambient switch is a interesting hypothesis, could be your problem.

It is raining, raining, raining. And it looks like I am going to get rained on all week week.
As soon as the rain stops I am going to look for and change out the L.A. switch.
B

It's me wondering what is going on with this unit. The unit is not equipped with a low ambient switch. Red wire to power on contactor. brown wire to capacitor. black directly from fan motor to contactor. Nothing in between.
The unit powers on. The fan starts. Contacter clicks, fan motor stops ubruptly. Then starts running again. It does this at the beginning of the cooling cycle several times. Everytime the fan moter slows to a crawl there is a definate power drain. All the lights in the house dim. I replaced the fan motor and both capacitors. It's still doing it. This is the first time this unit has started doing this. It's driving me crazy. The unit cools the house fine. I know something is not right in the condenser unit. It's going to fry something if I don't fix it. Maybe got a bad capacitor? Maybe I need to change the contactor out? Any suggestion? Help me please.
Thank you all.
B

Is the compressor trying to start when the condenser blower problem happens?

I'm thinking that if the compressor's starting is delayed, the high amperage drawn by it is pushing the voltage down which may be the reason for the blower slow down. A compressor delayed start-up is know to cause the light dimming you mention. Check this and give feedback

Hello pflor,
I believe you are correct. The compressor does not kick in until later in the cycle. The fan still is dimming the light and slowing to a stop before the compressor kicks in. Several times. The fan does this until the compressor kicks in then the fan stays on until the house cools to the thermostat set temp.

Bingo!!!
Though it may seem so, it is not the fan that is dimming the lights; it is the compressor. The fan slow down is, just like the dimming you reports, another consequence of the difficulty the compressor is having when starting up.

Here's what I think is happening:
-the thermostat calls for cooling
-the contactor contacts pull in
-compressor and condenser fan attempt to start
-compressor can't do it right away, so it pulls a very high starting current for a bit too long in trying to do so (start)...all the while, since amps and volts move in opposite direction, as amps rise in the circuit, voltage drops...low voltage slows down the fan to a halt
-likely you may even hear a snapping sound, meaning the compressor overload tripped (if it has an overload switch), giving the compressor a break...lights brightnen-up again, compressor takes a break, fan speed picks-up
-compressor tries again, likely starts (else goes thru one or two more tries, each time the blower will slow down...before the compressor finally starts, and the fan goes up to its normal speed)


You've got to help the compressor by buying a hard-start-kit...make sure you tell them is a 3-ton unit, just so you get the right size.

It sounds like just what is happening.
I'll get a hard start kit and see what happens.
Thanks

Big B you may want to make sure that your unit has a delay system installed on it. This is to keep the system from trying to restart too soon after it has kicked off (typically five minutes) if the unit kicks off and trys to restart before the system has completely equalized you will see this problem occur, due to the compressor trying to start against a high head pressure, just a thought there.

I am going to install a hard start kit tomorrow afternoon.
The compressor is a copeland scroll compressor.
Before I do this, is any other recomendations I should try?
Is the compressor false starting problem indicating that it is in need of replacing soon?
I am greatful for all the good info so far received.
Thanks.
B

Former Member's recommendation of a time-delay feature is a sound one. If you have at home a digital thermostat, those t-stats come with such feature already built-in.

It's hard to tell if your compressor will soon need replacement. Being online is not the same as being in front of the unit. But keep in mind that average life expectancy for these units is 15-to-20 years (up to 25 with luck and a solid history of maintenance and good upkeeping), so you have an aging unit there, and if maintenance has been lacking all these years, yeah, the compressor could very well be on its way to compressor heaven...so the pacemaker (hard-start kit) you're installing will help that aging dude continue giving you the comfort it has been giving you for some time (maybe even a few seasons) still to come.