air handler electrical problem

Empire_2

Condenser 220vac 1 phz... check unloaded, should have 220vac and 110vac on each leg to ground. If the contactor is pulled in then if you are reading 110, and considerably less on the other leg, you are reading thru the loads. RESRT the breaker and check the Cond with the unit off on line side of contactor. 220 should be there. Beware of 2 pole single throw contactors and the possibility of crap getting underneath the contactor armature.

Blower.....Without HP/ Amps, cannot be determined. although the start up amps will be considerably higher for about .5 sec....

Example: 1/3 hp @ 115vac fla=7.2 amps
1/2 hp @ 115 vac fla = 9.8

ddenny

airhandler electrical problem

hello carol
I've been getting a nusiance call where a 110 volt air handler trips a 15 amp breaker every few weeks. I checked the amp draw on the motor and it goes up to 22 amps on start up then settles down to 10 amps. the blower wheel seems to move freely with the unit off when I turn it by hand. it's an old air handler and I can't find any model number on it. can't read the name plate on the blower without removing it. do you think the ampeage sounds way too high and might that be an indication of the motor going bad?
also another question. when you go to a 220 volt single phase condensing unit and you get 110 voltage measurement to groung at each leg but nothing between line one and line two, but you get 220 at the breaker panel on the load side of the breaker is that an indication of an open somewhere? thankyou

carol_3

Hang on--I'm having a really busy day trying to get work done in time for the weekend. I'll be back with you.

LarryC

strange 220 Volt readings

"when you go to a 220 volt single phase condensing unit and you get 110 voltage measurement to groung at each leg but nothing between line one and line two, but you get 220 at the breaker panel on the load side of the breaker is that an indication of an open somewhere?"

Yes. One of the phases feeding the unit is open between the breaker and the unit.

Larry

Charles G.

Air handler

Check the Mfd output @ your capacitor and make sure it's the correct cap for the motor. Or it's a bad motor.

As far as your condensing unit voltage--disconnect the wire @ contactor BEFORE you take your voltage readings. Sounds like you're reading the SAME 110 VOLTS on each leg each time you go to ground. Why? Because you're running the voltage through the motors.

EBEBRATT-Ed

As far as the condensing unit the other posters are correct.

Air Handler--You need to get at the motor nameplate. The motor is drawing 10 amps. We have no way of knowing if this correct or not. The 22 amps is probably ok on start up IF the motor comes up to speed quickly. Make sure covers are on the AHU when you test as the fan will overload when the covers are off.

If this motor has internal overload protection it could be tripping on that if not starting properly. Does the motor run hot??

Need motor nameplate info and check all wiring connections between the panel to the motor. That's the first step.


ED

rucomfy_2

Transformer Load

I am afraid to ask but the only dumb question is one that is not asked........ How do I determine the max load on a 40VA transformer?? is it 40 divided by 24 or is it a function of ohms law and the pie chart? thanks

EBEBRATT-Ed

Yes you have it correct. 40va devided by 24 volts =1.66 amps. However their are other things to consider like inrush and voltage drop etc. You probably don't want to load it to 100%. Not a dumb question at all. I always need a review of the basics.


Ed