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Bob2007 · Sep 8, 2007, 01:29 PM

Hello,

I have an older version of Carrier Central A/C high efficiency system in which the relay has gone bad. The relay part number on the older part is: BL10SA made by GE (and made in the great US of A).

All the repair people wants me to change the whole unit. Is there a way to buy a similar relay switch?

Please advise and your help is appreciated.

Thanks,
Bob.

letmetellu · Sep 8, 2007, 01:57 PM

What does this relay control? If it is a contactor relay or a fan relay, I would think that you could find a relay of the same type or one that can be adapted to do what you want it to do.
I don't recognize the relay by the part number you gave. So instead of a number tell us what this relay does.

Bob2007 · Sep 8, 2007, 02:32 PM

Originally Posted by letmetellu

What does this relay control? If it is a contactor relay or a fan relay, I would think that you could find a relay of the same type or one that can be adapted to do what you want it to do.
I don't recognize the relay by the part number you gave. So instead of a number tell us what this relay does.

Okay.. this relay seems to be turning on the fan for the central A/C. How do I know it's this? Well, the fan is not running when the thermostat turns it on; I don't hear any buzzing sound from the motor; the furnace fan which distributes the air is on but the outside fan isn't on so I think that the relay isn't turning ON the motor.

I measured the voltages across few terminals to be about 21V-23V but what I don't understand is that the voltage only gets measured when I put the meter on AC can this be true?

The electrical terminals are all corroded so I am thinking of either replacing or cleaning them.

Hope this helps. I will post the photos soon.

Thanks,

Bob

letmetellu · Sep 8, 2007, 02:43 PM

OK now I think I understand that it is your outdoor unit that the fan is not running. So here is what I suggest, have someone to help you, you stand out side with the unit and let them turn the thermostat t the cool position and turn the temp down to about 60. Now you should hear a loud click in the outdoor unit. After the loud click you should hear the compressor start to run, at the same time the fan should start to blowing air. So it the contactor clicks and the compressor runs but the fan does not start here is what you do. If you have a cut off switch on the wall by the unit, turn it off. Now get a long screw driver or something similar that will reach the fan blades. Now turn the wall switch back on and as the compressor starts stick the screw driver into the fan and give it a turn in the direction it is suppose to turn, if it then continues to turn your problem is that you need a new condenser for the motor. If it did not turn on its own after you tried to make it turn it is probably a bad motor. There is a way to check this also but unless you know a lot about electricity I am not sure you should try it.

T-Top · Sep 8, 2007, 02:49 PM

Check your breakers first. Inside at your main breaker box and out side at the A/C unit. You may have a thrown breaker.

acetc · Sep 8, 2007, 03:54 PM

Letmetellu is correct in his advise but there is a type-o , he's referring to the capacitor , not the condenser. A person should always check the capacitors first because they are inexpensive and prone to failure. Mike

Bob2007 · Sep 9, 2007, 11:31 AM

Originally Posted by letmetellu

OK now I think I understand that it is your outdoor unit that the fan is not running. So here is what I suggest, have someone to help you, you stand out side with the unit and let them turn the thermostat t the cool position and turn the temp down to about 60. Now you should hear a loud click in the outdoor unit. After the loud click you should hear the compressor start to run, at the same time the fan should start to blowing air. So it the contactor clicks and the compressor runs but the fan does not start here is what you do. If you have a cut off switch on the wall by the unit, turn it off. now get a long screw driver or something similar that will reach the fan blades. Now turn the wall switch back on and as the compressor starts stick the screw driver into the fan and give it a turn in the direction it is suppose to turn, if it then continues to turn your problem is that you need a new condenser for the motor. If it did not turn on its own after you tried to make it turn it is probably a bad motor. There is a way to check this also but unless you know a lot about electricity I am not sure you should try it.

Sorry.. that's correct, the fan is not working. I checked the fuses near the outdoor unit and they are okay. Also checked with a meter and it's conducting (not an open ckt). Also checked the circuit breakers, they are okay. When I turned on the thermostat ON, no clicking sound happened but I turned the fan any way and nothing happened. The electrical contacts have corrosion on it. Can I clean it?

Thx. Bob

letmetellu · Sep 9, 2007, 07:01 PM

You can clean the contacts but it is a very tricky thing to do. They have a very small spring that makes them open when the power to the 24 volt coil is off and they are very prone to jump out of place and go off to small spring heaven. So be very careful and watch the springs.

hvac1000 · Sep 10, 2007, 01:50 AM

Replace the part. Once the contacts have been burnt from age and use filing them down or dressing them as they used to say is only a temporary repair. The part is available and can be replaced by you.

Bob2007 · Sep 16, 2007, 06:50 PM

Originally Posted by Bob2007

Hello,

I have an older version of Carrier Central A/C high efficiency system in which the relay has gone bad. The relay part number on the older part is: BL10SA made by GE (and made in the great US of A).

All the repair people wants me to change the whole unit. Is there a way to buy a similar relay switch?

Please advise and your help is appreciated.

Thanks,
Bob.

Hello,

I wanted to post pictures so that we can get better idea of what I am dealing with.

I am trying to understand, that other than relay (I think I have two of them), one is the GE relay and the other one is on the Potter & Brumfield Circuit board, which are the other parts and how does the system really works, i.e. the thermostat probes capacitor which in turn, turns on something else, etc. I need to id the parts so that I can go to the local a/c/ store to get the parts.

Hope the pics help.

Thanks so much,

Bob

hvac1000 · Sep 16, 2007, 07:03 PM

Originally Posted by Bob2007

Hello,

I wanted to post pictures so that we can get better idea of what I am dealing with.

I am trying to understand, that other than relay (I think I have two of them), one is the GE relay and the other one is on the Potter & Brumfield Circuit board, which are the other parts and how does the system really works, i.e. the thermostat probes capacitor which in turn, turns on something else, etc. I need to id the parts so that I can go to the local a/c/ store to get the parts.

Hope the pics help.

Thanks so much,

Bob

Where are the pictures?

hvac1000 · Sep 16, 2007, 08:56 PM

The PB board is a very old time delay setup. The upper relay as you call it is a GE/Mars product but the actual term used for this device is a potential relay. It is for a start kit that is for your compressor.(notice the large black round item laying on the bottom of the unit. That is the start capacitor that the relay puts in the circuit for a very short period to assist the compressor with starting. There are many different potential relays as they all have different settings as to voltage drop out. The other item is the start contactor that starts the compressor. It is the item in the picture that has the two small exposed screws on the front. Those are rated by amps.

The best way to fix this baby would be to replace the items but some are probably not available. The PB time delay board can be replaces with any 24 volt delay on break unit and those are available at all supply houses. The start/potential relay has to be specific to the compressor. It can be replaced with a unit that is close to the drop voltage listed on the relay itself.

The start capacitor is also available by MFD and volt rating as listed on the black round capacitor. The same can be said for the run capacitor. The run cap is used for both the compressor and the fan in the unit.

To bad I live far away. I could have it up and running in no time but with the new style parts it could be difficult for you to do the same. I used to service these units 30 years ago.

Now if you think you can get by with just the potential relay copy all the numbers off it. There will be more information on it that just the carrier number you listed in your first post. Be accurate with the numbers. In the picture they are red if this is the relay you are saying is bad.

Post that information and I will see if I can cross reference and get you the new part number. WARNING If you have to remove any wire label them well and the number on the relay from wence they came.

Bob2007 · Sep 21, 2007, 04:07 PM

Originally Posted by hvac1000

The PB board is a very old time delay setup. The upper relay as you call it is a GE/Mars product but the actual term used for this device is a potential relay. It is for a start kit that is for your compressor.(notice the large black round item laying on the bottom of the unit. That is the start capacitor that the relay puts in the circuit for a very short period of time to assist the compressor with starting. There are many different potential relays as they all have different settings as to voltage drop out. The other item is the start contactor that starts the compressor. It is the item in the picture that has the two small exposed screws on the front. Those are rated by amps.

The best way to fix this baby would be to replace the items but some are probably not available. The PB time delay board can be replaces with any 24 volt delay on break unit and those are available at all supply houses. The start/potential relay has to be specific to the compressor. It can be replaced with a unit that is close to the drop voltage listed on the relay itself.

The start capacitor is also available by MFD and volt rating as listed on the black round capacitor. The same can be said for the run capacitor. The run cap is used for both the compressor and the fan in the unit.

To bad I live far away. I could have it up and running in no time but with the new style parts it could be difficult for you to do the same. I used to service these units 30 years ago.

Now if you think you can get by with just the potential relay copy all the numbers off of it. There will be more information on it that just the carrier number you listed in your first post. Be accurate with the numbers. In the picture they are red in color if this is the relay you are saying is bad.

Post that information and I will see if I can cross reference and get you the new part number. WARNING If you have to remove any wire label them well and the number on the relay from wence they came.

I will post the numbers over the weekend (Sun). I did go to the supply store but too many relays there so I came home empty!:(

Thx. Bob

T-Top · Sep 21, 2007, 04:29 PM

The board with T1,T2,T3 is just a time delay board. The relay is your start relay that wires in with the start capacitor and in turn wires in with the run capacitor to help the compressor start. If any of the above go bad it will not work. The start relay and start capacitor can be changed out with a TO-5 kick start kit(cheapest way to go) and the time delay is not needed at all for the system to work.