Carrier ducted 380CA065-303

[paul_h]

Stuck with one of these old carrier systems right now.
Back story is thermostat cable damaged, so replaced by an electrician.
Apparently it worked OK for a while but now it will start, but once it's cycled off and won't start back up.

The contactor is buzzing away and if you press it in, it holds and runs normal, and cycles off again normally whenever the thermostat stops calling for compressor. It seems to be wired up OK, just something in the outdoor unit playing up. HP and LP switches are fine, time delay I don't know(not really good at testing the old cube, I just bridge and if it still doesn't work, look elsewhere and assume the cube is fine)

What I need to know is what type of interlock is in the circuit to hold the contactor in when manually pushed in, and what part of the control circuit is stopping it operating.

I've checked all the safetys and they're OK, but don't even have a circuit diagram that's legible anymore.

Anyone know much about these dodgey control PCB carriers?

[nassrifi]

Dear friend
Usualy, such cercuits hold them selves by aug. contacts within the same contactor.
having a contactor buzzing and not able to latch means that eather it is malfunctioning( replace contactor) or there is a leak in the control cercuit that the volts across the contactor coil is droping( witch is more likly in your case as i understand from your massage).
there for a close and deep look should take place specialy when there is no diagram available. changing wires, cleaning ,retighting contact screws, Isolating from bodey may do the trick.

best regards

[Brian_UK]

As the man said Paul, your contactor is shot or there is a control circuit fault, loose connector somewhere.

[Gibbo]

Is the new cable the same as the original cable. Sounds like voltage drop to me due to the cable.

[paul_h]

May be right, the electrician used telephone cable after finding out it was 24Vac and on a 2A fuse. There is 24Vac at the outdoor unit though and it normally turns on at least once.
I went there tried heat mode, it worked, tried cool mode it works, then wouldn't start up again after cycling off.

edit: I think there's an unused wire in the cable I'll double up on for 24V active, and I'll use the W2 wire to double up for 24V neutral since I don't think W2 is really used anyway?
If that doesn;t work, I'll see if I have a spare contactor and 24V coil.

[paul_h]

Well I doubled up the 24v like I said, and it seems to work. Crossing my fingers that it's sorted and I don't have call backs anymore based on what someone else did.