# Carierr Condenser Not Starting Unless Contactor is pushed in



## steve987 (Aug 28, 2009)

I thought I had a faulty contactor relay so replaced it. With the new one now in I can only get the fan and motor to work if I push in the contactor button (in the middle of the contactor relay). Its exactly the same piece as the other one - I havent checked the 24v piece.

Any ideas on what it may be. I get no noise or humming and when I push the button in manual with a screwdriver it works fine but the contactor will not hold the button in on its own.


----------



## manhunter (Aug 28, 2009)

Could be bad out of the box.

The easiest way to check is check voltage to contactor, It should be at least 24 volts, if you do than take back old part to be exchanged.

Silly thing to ask but you did adjust the thermostat for the ac to come on I hope.

Putting that aside, when you switch to ac does the indoor blower come on?

If that is functional then follow the 24 volt (not the hi-voltage)wiring from the 

ac back to furnace check for breaks or frays. Make sure connection at furnace (R-Y and C terminals).

If theses check good turn off power to furnace and jumper the wires in thermostat. Terminals R and Y should be used,

If ac turns on the thermostat is bad.


----------



## steve987 (Aug 28, 2009)

Thermostat was set to come on. Inside blower and inside unit (piece in the garage) comes on when I set the thermostat to come on so I think all that piece is good. 

Thanks - will check the other wiring pieces.


----------



## hennyh (Nov 14, 2006)

How old is the system?

Most systems have a control board that energizes the contactor when there's a call from the thermostat AND the system is normal as defined by pressures. (ie too low or too high will lock out the system regardless of what the thermostat is asking for).

Measure voltage of the incoming control signals but you also need to look at the input directly to the contactor from the control board. 

If the thermostat says "turn on" but the control board says "no way" then you either have a bad control board or other conditions haven't been met such as pressure lockouts or delays. By manually engaging the contactor, you're potentially overriding any condition trying to protect the system.

Try and get the complete wiring diagram. Don't forget to pull the disconnect when doing all this testing. You don't need (or want) 220V until you're sure the contactor is engaging. Then you can do final checkout with 220V. Be safe!! 

P.S. You might also have weak 24v from the LV transformer or thermostat. Use the good relay you just replaced and see if it will get energized directly by Y-C when there's a call for the HP to come on. (temporarily disconnect Y-C from HP to do this test)


----------



## steve987 (Aug 28, 2009)

The house is 5 years old; so I assume the AC unit is five years old too.

I dont know the model number until I get home later today. 

Thanks anyhow


----------



## SKIP4661 (Dec 3, 2008)

Since you replaced the contactor, it is safe to assume the unit had already stopped working. If you have high and/or low pressure switches to monitor the refrigerant pressures you probably have a freon issue.


----------



## steve987 (Aug 28, 2009)

*Skip was right*

Yes was a freon issue -- saw oil on the copper pipe -- 10lbs of Freon needed though so not cheap -- thanks


----------

