Check your voltage drop to contactor. Check conductor size.
Can anyone help with this one? I have this 12 ton carrier package unit that has a call for cooling but compressors arent running or outdoor fans. I got voltage but contactors are not engaging. I was told to just hit the disconnect and give it five minutes and turn it back on and it will run. I took a look at it and and found the contactors wont pull in, with a little nudge they suck right in. any ideals what i can look for. model number 48 HJF 012 571HQ thank you for any help.
Sounds like a bad contactor coil to me.
i have high voltage and good low voltage to contactor and its not just one contactor its both compressors and outdoor fan contactor
I am not the greatest trouble shooter for sure - but if you have good control voltage, and the coil is not engaging enough to close them, I would think either something wrong with contactor coil -- or more probable as you said someone suggested in your previous post Loose connection somewhere-- possibly the board has a setting of higher than 5 minutes before it can be turned back on ???
I have 3 contactors and all of them are not fully engaging. I did ohm out the contactor coils and they tested good. I am getting good voltage at the relay. I didnt ohm out its coil. Today it ran fine. Seems like every other day and up to three times a day i have to pull the disconnect or just push in the coils. i will check out the line voltage at the disconnect and see if i am gettin a full 440. I am not sure where to go from there. thank you for your help so far.
Most Carrier unit there is Compressor lock out circuit board for each compressor sometimes unit wont come on when its call for cooling your circuit is open check that first. good luck
Wait, What? Is this a question, or are you teaching us something??
EDIT: Sorry, my browser popped up with thread #7 first sorry 'bout that.
Last edited by DavyB; 05-08-2010 at 12:04 PM.
Not tryin to teach anything dave. I will recheck the components mentioned. Thank you for everyones help. It almost seems like weak magnets but on all three contactors? And the issue is not constant. I am just out of school and starting to see how much I dont know lol. again thanks for everyones time. glad i found the site.
Sounds like a low voltage problem. One contactor, maybe contactor problem. All three, possible voltage problem. Could be Clo problem also, they act up alot on Carriers.
Just so I have this right. With a call for cooling you have good low voltage at the contactors but they are not pulled in. If this is the case, I would replace one of the contactors and see if it works.
Are you sure you didn't check the voltage at the contactor while it was pulled in?
First this is a 10 ton unit.
Second fallow the advice of Davy post #9.
i am thinking its your transformer. u may have 24 Volts but the VA may have dropped..Enough voltage to do the job just just not enough ass behind it.
define good low voltage, at around 22 you will have trouble pulling in contactors.possibly transformer tapped wrong?
This could be more than one issue. The behavior of pushing in the contactors and they hold is the classic reset of the CLO, compressor lockout board. Your unit has two of these little boards, with a power wire passing through a metal sensing loop.
When you look at the unit, and you have a call for cooling at Y1, make sure you have the same voltage coming back from the economizer, if you have one.
Then BEFORE pushing in the contactor, look for the control voltage at the coil terminals. If it is not there, and then, if you push in the contactor and it holds, you have a lockout issue.
If that is the case, start checking everything else. Pressures, superheat, subcooling, condenser and evap delta T, fan operation, etc.
I have seen low suction pressure as the number one cause of compressor lockout on these Carrier units.
If you have voltage at the compressor contactor and it does not pull in, measure the current. Does the current change if you:
a) jump R to Y1 at the terminal strip?
b) eliminate the Y1 circuit from the economizer? (use the economizer plug or jump the terminals on the economizer logic module)
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Did you check the contactor voltage at the coil before or after pushing them in? Have you checked the voltage with the wires off of the coil? My first guess would be the CLO because when you reset the unit ,it works. check all while it is running and hopefully you will find why it is locking out.
Does this unit use semi-hermetic compressors? Also I had a carrier about the size you describe doing the same thing after I rinsed the condenser on a cold day. Somehow when the low pressure switch opens it keeps the contactor from pulling in on it's own. But if you push in the contactor it stays in. Another tech told me that is how carrier locks out some of their gaspacks (CLO board). Check your pressure switches or put tattle tales across them and come back later. I agree with timebuilder and pdrake65.
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