Carrier expert needed

**oldtimer2** · 10-03-2009, 10:04 AM

Carrier RTU-48tmd016511ba 0408u02577 New unit,another contractor installed. Condenser coil was damaged during install. Long story short he is out,were in. Replaced coil with no problems,go to start, call for cooling, no compresseor no cond. fans. no 24 volts to $2 on CLO. Start seaching, found at plug P1 5 wires going out to the economizer ( 3 to the damper actuator and 2 to the o/air sensor) found no economizer module. This can not be correct . According to the diagram Y1 and Y2 both come off low voltage terminal board thru economizer module and back to #2 on CLO.

I think I am missing a wire harness and economizer module.
Economizer mod. is CRECOMZRO10BOO
Called local Carrier rep. no help Can anyone tell me what I need and part numbers if possible.

**timebuilder** · 10-03-2009, 11:06 AM

Wait. You are saying there is no logic module to which the wires connect?

**timebuilder** · 10-03-2009, 12:05 PM

Check those first four diigits in the model number. 48tm comes up as an obsolete unit (manuafactured more than 5 years ago). That ID cluster should not be possible for a 2008 RTU.

**timebuilder** · 10-03-2009, 12:18 PM

I found a current unit, a 48TJ016.

Look at the CLO board on the diagram. Just to the left are the jumpers used on this model, with a reference to "note 3."

If you follow the wires down in the diagram you will see the logic module connections. The logic module attaches to the damper actuator, and has two rows of recessed male 1/4 inch connectors.

For example, the yellow Y1 wire should connect to terminal #1 on the logic module. With the enthalpy setting of "D" and the temp warm enough, the dampers should be at minimum position and a call for mechanical cooling is sent from terminal #2 on the logic module, and the blue wire is energized to terminal #2 on the CLO board.

If that logic module is missing, there can be no cooling except if the dampers are left open, and the fan is running on a cool day.

At this point, you need to:

1) verify the model number
2) find where the wires that come from the pass-through P1 connector are being terminated, or
3) make certain there is a logic module (also referred to as an enthalpy controller) installed on the damper actuator motor, and the wiring is reflective of the diagram.

**oldtimer2** · 10-03-2009, 01:10 PM

The model is what I read off the unit. There is no enthalpy module. At plug 1 I had to jump plug conns. 5 & 8 for 1st stage cooling to come on, 6 & 9 for 2nd. stage. I think there should be another wire harness going from plug #1 to the enthalpy module and then from the module to damper actuator. I called 59th st. and got no help. (friday afternoon )!!
The jumper plug is not in plug #1 It's like they pulled the jumper plug out and plugged in what was there, which in this case was the wire harness for the actuator.
Summmary: On the back side of plug #1 are 5 wires, 3 go to the damper actuator and the other 2 go to the o/air sensor!!! I don't know what the numbers are off the actuator, but it is not a honeywell with the module on the top.

**timebuilder** · 10-03-2009, 01:22 PM

I would think that only a logic module would be capable to looking at the enthalpy sensor and choosing economizer or mechanical cooling.

**timebuilder** · 10-03-2009, 01:24 PM

Send me a PM and I will give you the Carrier portal for docs.

**Dallas Duster** · 10-03-2009, 01:26 PM

Kinda sounds like someone gut the economiser section should be a honeywell controller in there somewhere. The TM series is a newer series than the HJ and TJ.

**oldtimer2** · 10-03-2009, 01:32 PM

The way I found the machine,there is no way the mech. cooling could have run. Off the lvtb at Y1 blue wire goes to plug #1, on the back side of the plug there is no wire connected. Thats why I think they just connected what was there. I think I need :
enthalpy module
enthalpy control
wire harness
I don't know part numbers and 59th st. is not helping me.

**Dallas Duster** · 10-03-2009, 01:37 PM

Check back later I will look for you , swapping a cooler barrel at the moment.

**timebuilder** · 10-03-2009, 03:00 PM

Originally Posted by thegoodlistener

Kinda sounds like someone gut the economiser section should be a honeywell controller in there somewhere. The TM series is a newer series than the HJ and TJ.

When you search the Carrier doc site with "48TM," the one doc listed says "obsolete," and shows a manufacturing range of 1992 to 2002.

This is the current 48TJ from the doc portal:

http://www.docs.hvacpartners.com/idc...it/48tj-4w.pdf

The 48 and 50 series units (48tm and 50tm) are units with a capacity code of 004 - 016.

**timebuilder** · 10-03-2009, 03:01 PM

Originally Posted by oldtimer2

The way I found the machine,there is no way the mech. cooling could have run. Off the lvtb at Y1 blue wire goes to plug #1, on the back side of the plug there is no wire connected. Thats why I think they just connected what was there. I think I need :
enthalpy module
enthalpy control
wire harness
I don't know part numbers and 59th st. is not helping me.

Try PP on Ave of the Generals in Norristown.

If nothing is there in the unit, you may need:

the harness from P1 to the actuator motor (PL1-R on the diagram)
the logic module
the Damper Motor (DM) (hopefully that is still there)
OAT (outdoor air temperature sensor)
MAT (mixed air thermostat)
CLS (not defined on the diagram, but I might call it a Cooling Lockout Switch)

See the bottom of page five, and page six of the link I posted.

Hopefully the harness from P1 has a break-off for the OAT and MAT sensor connections.

One more question: it's difficult to get to the backside of the P1 plug. Did you just wrestle it free from the hole?

**oldtimer2** · 10-03-2009, 04:24 PM

Time, I took the rain hood off looking for the parts I needed. There is a small blankoff plate behind the rain hood, once removed you can see the back side of plug#1

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