air-conditioningelectricalhvac
I need to replace my A/C contactor, but I'm not sure what exact model I need for the new part. I took two photos showing the Brand and model number of it but when I search it on Amazon, I cant seem to find the exact one. I was wondering if I can use different brands instead of the one I have put in right now, I'm just not sure. Can someone maybe give me a link to a one which is compatible with this model or explain what other ones I can use.
Brand: Honeywell
Model: R8243A 1031
24V 50/60HZ
You should check the wiring in the furnace. There are no standards for thermostat wire colors, so you can't always trust the color of the wires. Seeing how the wires connect to the furnace, is a sure fire way to figure out what's what.
The O (cool mode) and B (heat mode) terminals are usually used for a reversing valve, in heat pump systems. I'm not familiar with oil systems, so I can't say for sure what they would be used for.
Some thermostats have separate O and B terminals, like this.
Others have an O/B terminal, and use a jumper to select which should be used.
Since you have a multi-meter, you can check the voltage of the wires at the thermostat. Make sure the meter is set to AC (Alternating Current) in this case, and if there are ranges, something safe for 24v. Probe the Red and Blue wires and see if there is 24v. You can also check the voltage between the red and any other wire.
If there is no voltage, the low-voltage power supply for the furnace is bad or not getting any power. There is probably a breaker in the main cabinet for the furnace, but there will probably be a breaker located on the furnace/air handler as well. Make sure they are both on and recheck the voltage.
The power supply will typically look like this and should have two 120v wires and two 24v wires coming off of it.
If you can find it, check the voltage going to it to see if 120v is present. Troubleshooting will move on from here if there is not 120v.
Thermostat information
Assuming the wire colors you have are standard...
To turn on the fan, the thermostat makes a connection between the red and green wires. If you place a jumper between these wires, the fan should run.
To turn on the heat a connection is made between the red and white wires. The call for heat will always be accompanied by the call for fan.
The blue wire doesn't signal anything - it just supplies voltage to the thermostat in conjunction with the red wire. To draw a parallel with your house wiring, the red wire is like the black "hot" wire, and blue is like the white "common" wire.
Best Answer
I searched R8243 and came up with a Honeywell cross R4243b1012.
Part numbers change all the time but this should be a compatible part 24v coil and a double pole contact set without knowing your compressor size it would be hard to guess at the right size because Honeywell did not provide the specs for the original.
It’s not a big deal as long as the control voltage 24v is the same It’s a double pole motor contactor the last part would be the HP rating. Well and it fits. It won’t hurt to get a larger one as long as it fits. I put larger ones in all the time the contacts actually last longer.