Hi All,

We are trying to replace a 3-wire fan (GE S325) in a Rudd (Model UAMB-036JAZ), with a new 4-wire AO Smith ORM5458.

Going through some of the posts over here it seems that the Brown and Brown/White on the new fan will go to a fan capacitor. So we bought a matching 7.5 mfd cap to go with the fan.
I now need help hooking up to the old Honeywell R8242A contactor.
The following are from the old wiring diagram with the old motor:
RUDD Photos by knpnj | Photobucket

I have so far understood that:
1. the Yellow and brown 24V pair will go the "front" of the contactor.
2. The original black pair (L1 and L2) will go to the "bottom" or "right" terminals of the contactor when the label is facing you.

This leaves me with five wires to care for:
1. The black and white pair from the new fan - goes to T1/T2 on the "top" (screw-in) or "left" of the contactor with label facing you (?).
2. The black and Red leads coming from the condenser.
3. The orange lead from the old 3 terminal capacitor.

Per the diagram posted by Houston in this post and others, all five of these should be sitting on this top/left side of the contactor?
Or does the Red from the condenser go and sit on the same terminal as the Orange on the old capacitor and then the other end of the Orange come to the contactor to T2?

Lastly, the Green cap on the old capacitor is now left empty? This was holding the Brown from the old fan. I have the Purple from the condenser to the old capacitor as-is.
Please let me know if I have this all wrong

As always, appreciate all the help.
TIA

 

The attached diagram should point you in the right direction. Of course, the wire colors from your compressor may be different. Don't forget to remove the drain plug from the bottom side of the motor. If you require any assistance just post back.

Don't forget to make sure the fan is turning in the right direction. The wiring diagram on the fan will show you how to reverse direction, if necessary.

Compressor connections to Run Capacitor (as shown in second diagram)

(C) Common winding--goes to T1 on contactor (black wire in diagram)
(S) Start winding--goes to Herm on contactor (blue wire on diagram)
(R) Run winding--goes to C terminal on run capacitor. The Run winding is also connected to T2 of the contactor. (red wire on diagram)

 

Great. Thanks for posting so quickly.
Yes, I have the drain plug out of the new fan and they have provided the wires to cross in case I need to reverse the fan direction.

Now over to the contactor.

Per my setup so far, I am Ok with the "C" and the "S".
The Common from the condenser is a Black wire and it will go to T2.
The Start from the condenser is a Purple wire and I have left it as-is on the old capacitor.

I just want to be sure before I hook up the Run "R" winding.

The Run winding from the condenser is Red and in the old hook-up it appeared to go straight onto T2 on the contactor, not the Capacitor.

But now we are saying the hookup should be:
Red from condenser --> to C Terminal on Capacitor -- (shared with) -- Orange from C Terminal on Capacitor --> to T2
(?)

Thanks!

 

Yes, red from the compressor run terminal and orange from the capacitor C terminal connect to the contactor T2.

 

OK thanks Houston204.
So for my new setup I have:
T1 = Two Black leads (Fan and Compressor)
T2 = White (from Fan), Red (Run Terminal from compressor) and Orange (C terminal from Capacitor)

Will do this tomorrow and report back.

 

Hi All,

I now have the following as mentioned earlier:

T1 = Two Black leads (Fan and Compressor)
T2 = White (from Fan), Red (Run Terminal from compressor) and Orange (C terminal from Capacitor)

The new motor was mounted with blades from the old fan, the drain plug was removed and the new capacitor added to the circuit:
Rewired with additional capacitor: New Capacitor And Wiring 0914 Photos by knpnj | Photobucket.

I am getting 239V on the two leads on L1 and L2.
However, when I turn the Thermostat to cool, it does not appear to be calling.
I do not see 24V across the two leads on the contactor (Brown and Yellow on the front).

Manually pressing down on the contactor plunger does complete the circuit, condenser kicks in and the new motor/fan works as expected.

I guess I need help troubleshooting this through the Thermostat now..

Thanks!

 

There is a very good possibility you blew a fuse at your air handler. Test for 24V at your thermostat. With system turned to OFF set meter to volts ac and place one lead on the R or RC terminal and one lead to G or Y to see if you have 24V present. If you don't have 24V there then turn power off to the air handler and look for an automotive type fuse either wired in to the transformer;s low voltage side or on the control board depending on which system you have. If that is the problem, simply replace that fuse, restore power and you should be back in business.

 

OK thanks.
I will trace the 24V from/to the Thermostat later.

Meanwhile, in case it helps, when the Thermostat was set to Cool, the Air Handler did not kick in. However, turning the Air Handler Off and then On manually did start it up (but not the Condenser at the same time). Turning the Thermostat Off would stop the Air Handler, but not bring it on again if the Thermostat was set to Cool the next time.

The Air Handler is Carrier, appears to be Model 40RS (or FS?) 160 310 - not sure which fuse at the Air Handler - I have two fuses showing on the outside: Air Handler Z1 0914 Photos by knpnj | Photobucket
However, if there is a separate control board fuse, I'll have to find where it is located.

Thanks.

 

It sounds like it may be a thermostat issue. Do you have a battery powered thermostat or is it powered through the C terminal? If it is battery powered thermostat and if the batteries are low it will cause it to act erratically. All you would need to do then is replace the battery and see what happens. If that doesn't prove to be the issue, one simple test you can do to eliminate a problematic thermostat is to turn off power to the air handler and remove the wires from the R, G and Y terminals at the thermostat. Then connect those three wires together (I like to use a small blue wire nut) and turn the power back on. If the system operates normally that points to a problem at the thermostat.

 

My previous post was incorrect - I had the Tstat Fan position on "Auto".

The Tstat is a Honeywell Chronotherm-III and this is how the current system runs with it -
1. Turn the Fan switch on Tstat to On - the Air-handler runs instantly.
2. Leave the Fan on Auto and set Cool to 5 degrees below current temperature - The Air-handler kicks in after a few minutes, sometimes longer than few minutes (previously this made me think that nothing was happening).

In either case above, the Condenser never kicks in (not getting 24V at the Contactor).

In case I still need to test the system at the Tstat, this is the current setup - Tstat Wiring
Please let me know which one to connecd together (R or Rc) with the G and Y, if needed.
If there is a 120/24V transformer somewhere on the Condenser circuit, I am thinking it has blown, but not sure. I'll have to find it if there is one.

Thanks

 

If you do not have 24V at the contactor you will need to figure out where you are losing it. It would appear the transformer is sending out 24V as you say your blower starts up. The 24V needed at the contactor starts at the transformer inside the air handler and ends up at the condenser using two wires (brown and tan) going to the contactor. You will need to locate those two wires where they exit the house and test for 24V at that point. You do that by setting your meter to volts ac and testing across those two low voltage wires.

I suggest you first test for 24VAC at your thermostat.


I reviewed the photos you linked. I noticed you did not have a jumper wire between R and RC on the thermostat. A jumper is normally installed between these two terminals unless you have a dual transformer system. On your photo I drew in the jumper to which I am referring to as absent. On some thermostats the instructions state you remover the jumper wire only if it is necessary to install a wire on R and RC.

Can you post photos of the air handler where the low voltage wires are connected?

Edit: I just reviewed the photos of your condenser. It appears you may have your yellow wire that should go to the contactor located on the wrong terminal or it goes to a time delay control (probably the case). On your photo I circled the hole where the tan and yellow wires enter. Your tan wire is routed properly. That yellow wire should normally go to the terminal where the heavier gauge yellow wire is on the contactor.

With power off follow that yellow wire (with added red dashes) coming through the hole and see where it is going. It is probably going to a time delay device and the heavier gauge yellow wire is from the time delay. If you do have a time delay control installed you will need to trace the 24V from the thermostat up to that point. That time delay control could be the problem by not allowing the 24V to pass through. You can bypass the time delay device for testing purposes to see if that is the case. I have attached a photo of one type of time delay control. Just follow the yellow wire off the contactor and you will locate it.

 

Good catch Firedawg.

It is probably a pressure switch that requires resetting.
Newer Rheem/ Ruuds have it just below that control box but older models may the reset button outside of the condenser.

 

Hi All,

I finally had another chance to look at the layout today.

1. I believe we do have a dual transformer system, though I have not specifically checked for the 2nd transformer for the air handler/cooling circuit. I did replace one a while back when we lost hot water. In any case, there has never been a jumper between the R and Rc on the 1st zone Tstat.

2. I went out and opened up the panel again to trace the yellow wire - it appears to run to the high pressure end and then to the low pressure switch that Houston204 mentioned. I took a couple pics, but they didn't come out too good.

I checked and found no presence of the TDC - it is shown in the circuit diagram on the panel as optional.

Hence, the only option I had was to reset the pressure switch. I cleaned it up and pressed it to hear a good click.

And that's it. As soon as the Tstat was set a few degrees below current room temperature, the air handler started up in a few minutes and so did the new motor and fan!

I let the system run for about 40min or so and it seemed to run fine. I have a feeling that the refrigerant level may have dropped over the years, but over all it does seem to function. The weather in NJ is already too cool for using the A/C for the rest of the season. I am guessing I am done with this for now.

A big thanks to everyone for the timely help!

 

That is great news

The high pressure switch should trip any time that a condenser fan motor fails to start so the cause has probably already been resolved. (Though the outdoor coil should be rinsed annually)