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paul_h
11-08-2010, 11:21 AM
What does it all mean?
I think I've come across similar in a goodman, but they were easy to work out.
I've got a 38YCB036903 O/U, And a 40 QCA I/U.
Someone has cut the wiring to the Enerstat SHP-1 during renovations.
I've worked out what all the W1, Y1, G, R, O, B on the enerstat mean, but need to tie them in with the carrier terminals.

Also from the outdoor unit there is a small white cable connected to C,Y, O, W2 and R. ( black, yellow, green, white and red respectively)
At the indoor unit the cable from the outdoor is a 4 core different black cable, and only red, green, yellow and brown. So there's a join somewhere, but I'm sure that the interconnecting cable wasn't tampered with, just the thermostat cable. But any ideas how that would work!? Something to do with the fan motor not connected to the outdoor control board? Is that a normal set up?

Many more questions (extra relay hooked the the enerstat thermistor terminals?- might have something to do with the fan), but I'll sort out the basics first.

Thanks.

Brian_UK
11-08-2010, 11:31 PM
Not exactly your model but has the basic Carrier wiring scheme in it, page 6..

http://eto.carrier.com/litterature/iom/013-889.pdf

paul_h
12-08-2010, 12:15 AM
Thanks, already had the wiring diagram which is useless due to showing only a 'like for like' carrier thermostat with the same terminal names and not explaining anything.
But your link had the "sequence of operation" which it explained it.

C is 24v neutral
Y is compressor
O is reversing valve
w2 is aux heat
R is 24V active
G is indoor fan

paul_h
12-08-2010, 09:32 AM
I went to another one today, feeling confident.
Confidence didn't last long :(

That system only had the i/u fan run 24v signal wire connected to the controller, and there's only one wire added to the fan relay to go to the outdoor unit to run the compressor.
No other controls! All the cabling was there at the thermostat for fan, compressor, r/v etc, just never connected.

O/u was a hitachi with the control PCB disconnected, just the one 240v wire from the indoor fan relay to run the compressor contactor whenever the enerstat switched the indoor fan on!

HVACRSA
26-11-2010, 09:28 PM
Having a problem with a APAC (Carrier) 24v Control system. I have checked transformer which has a output of 24v but at the contactor for compressor I am only getting around 14v which is not enough to energize. I have also tried a new contactor. What also confuses me is that at some points, I think it was Y and O I get 30v! Indoor fan motor starts up but that is about all that happens. I have checked relays etc and they all seem to be in working order.
Anybody have suggestions or come across something similar.

Brian_UK
26-11-2010, 11:46 PM
Low volts mean that there is/are some dirty contacts somewhere.

A wire is coming loose or a set of contacts are worn and not making properly.

Always check your volts back to the same reference point, say 0 volts at transformer.

paul_h
27-11-2010, 08:54 AM
Yeah make sure when you are checking volts, to be checking then across the 0V of the transformer.
Also I doubt the 24V from the thermostat goes straight to the compressor contactor, there would have to be some cut out switches (HP/LP, overload, defrost PCB etc)

HVACRSA
28-11-2010, 12:44 PM
Thanks. But a little confused what you mean by checking them across the 0V of the transformer. (neutral?)
Paul the thermostat does go through a HP and LP switch including delay timer.

paul_h
28-11-2010, 12:52 PM
Yeah, neutral of the transformer, not mains neutral.
You mentioned only 14V at the contactor, but what is at the thermostat output? at the LP , the HP and the delay timer inputs and outputs? Find where the voltage dips, could be the thermostat output, or anything in between that and the contactor. Maybe bridge out the delay timer?

HVACRSA
28-11-2010, 01:04 PM
I checked safety switches, delay timer etc. all to mains neutral :( Oh well guess that is how I learn. I was not sure what C, Y, O, R was either until checking online. I will be going back to site sometime in the near future.

paul_h
28-11-2010, 01:50 PM
Did the same thing myself until I worked it out.
Ever since I started this thing called life, I've never been trained by anyone. I'm self taught and had to learn from my misadventures and mistakes.
From school to fixing my own cars, to tech college in refrig, to apprenticeship (just sent out to work it out myself), to trade (just given a van and told to disappear and bring money back), to self employed (every mistake costs me money, everything from finding hard to get parts and info to working out invoicing, paperwork and taxes I've had to work out the hard way). I've never really had anyone to rely on, who knew more than me and was willing to teach it to me. That's why these forums are great. Finally some people that know more than me I can ask questions to!

But my circumstances/upbringing/education is why I'm rubbish at theory and all my info is just rough practical stuff :D


Edit: Don't forget even if there is voltage at the contactor, there may be cut out switches after the contactor to make the circuit incomplete to the transformers neutral.