contactor wont pull in?

[pony]

i ran into something got me scrach my head,i am little green on electrical,maybe some hvac tech can give me a tip or two,got 28v(dont think little high matter) from controlboard to contactor when it call for heat,but contactor wont pullin,and change contactor,still same thing wont pullin,i jump wire stright from R and C to contactor,and it pull in,if board is bad it shoulndt send 28 v to contactor,if contactor is bad,i jump R and C to it,it shouldnt pull in?what ur think i need to look,check loss wire it all fine,got 240 v L1 and L2,good ground,need help,thanks

[2sac]

Phantom voltage.

[2old2rock]

Look at the schematic. There is something else in the circuit.

[Sleuth]

.
Maybe board, maybe lps. Is this HP etc....?
..

[GorillaTight]

I would agree with Sleuth and say there's probably a pressure switch holding you up. If you check "R" to any ground, you'll get 24v. But the pressure switch may be breaking the "Common" side of the circuit; although unconventional, it's possible. Slap those gauges on it!

[pony]

all wiring check out correct,and try start it again,again have24 volt to contactor,but contactor wont pull in,this time i didt mess with it,and guess what it fire up after about 8 mins?must be the board have safty delay,cause thermostat already stop flashing,thermostat go solid heat on,dont it should start it when thermostat go solid heat on?but this unit dont do that?guess new things everyday,what u think it might be?control board delay?

[pony]

i already check the pressure switch,it stay close,thanks for the tips.but if the pressure switch is open,it shouldnt have 24 v to the contactor,correct?thing i dont understand is why it have voltage to the contactor,but it wont pull in?it is new contacotr,and jump R and C direct to contactor and it will pull in,???scratch my head?lol,any input?

[Sleuth]

.
If you have R going to a board on the HP(?) "outdoor unit" you'll have a delay.

And every time you break it'll start your delay over.
It sounds as if you're looking a defrost control board. I can't see it from here.
..

[pony]

it is 2005 tempstar 1.5 tons heat pump,board number is 1069364 made by ranco,thanks,just never see thermostat heat on go solid unit fire up after 3-4mins instaed right away,,dont it should be comeon right away afterneat heat on turn solid?

[Saturatedpsi]

all wiring check out correct,and try start it again,again have24 volt to contactor,but contactor wont pull in,this time i didt mess with it,and guess what it fire up after about 8 mins?must be the board have safty delay,cause thermostat already stop flashing,thermostat go solid heat on,dont it should start it when thermostat go solid heat on?but this unit dont do that?guess new things everyday,what u think it might be?control board delay?

Time delays are generally 5 minutes or less...and sometimes designed into the common circuit. And sometimes they get flaky/inconsistent or fail to "turn on" altogether. Seen it a lot with Carrier boards.

[timebuilder]

Model and serial..............

[stephy]

I'm sorta confused...which happens often..:D

You should have 24 volts between Y and common at the contactor.............

It appears your common is broke some where....go out to the van and get something else that has a 24 v coil, see what it does......

Been there.........:putergreet:

[gravity]

had this happen over the summer.

take a jumper from where C(common) comes into board and put it to the common side of the contactor.

make sure your safetys in the circuit dont break common.

if this jumper works then you have a failed circuit in the board and u need to replace it.

[OhioTech]

Did you put your meter across the coil to check voltage or one on contactor and to ground? Must have the 24v on coil..meter leads on each side.

[ductductgoose]

Did you put your meter across the coil to check voltage or one on contactor and to ground? Must have the 24v on coil..meter leads on each side.


common mistake made by new techs (false readings:gah:)

:cheers:

[Kevin Weaver]

do you read 24volts at contactor with the wires connected to contactor or wires in the air NOT connected to contactor??? This will help resolve what your talking about. Be sure to put your meter leads on the terminals of the contactor and no where else with the wires connected.