carrier 30gx oil separator heaters

[Coolie]

Hi
A colleague of mine recently condemned the oil separator heaters on both circuits on a carrier 30gx air cooled chiller.
I attended to replace the heaters and after slogging it out, removing the lagging and making it all good again I discovered that the heaters still were not working. I know that they are only energised when the discharge temp is below 40.3 degC and turn off when it goes above 43.6 degC. My colleague isolated circ b, so the crank case heater was at ambient temp when i performed my repairs. So in theory, the heater should have been energised.

The heaters are 415v fed via a contactor and overload. The coil of the contactor is wired directly to the control board, so no other fuses or safeties as far as i am aware.

I attempted to get into the controls, but the default password (11) was not working, so I can't even see if that setpoint can be altered, or if it is programmed into the strategy at manufacturer. I attempted contacting carrier for assistance on this, but was directed to their website to download the manuals...which i already have. My only other option is to get carrier to attend site, but that is my last resort...so if anyone has any suggestion, I'd appreciate it

Thanks in advance

[Coolie]

Oh, i forgot to say that i compared the actual discharge temp with that on the controller and they were within a 10% variation, but still bellow that crucial 40.3degC

[Coolie]

It's running on a pro dialogue plus control system as the comp's are screws.
Oh, and i also checked that the contactors were ok. They were not getting the 24v control voltage onto the coil from the board. The board did have a healthy 24v supply.

[chill bill]

Hi coolie, I have had the same thing recently, but found the contactor for the heater had welded closed, therefore burning out the heaters. There is a test mode in the pro-dialog controller to manually run the heaters. Check controller manual on outputs.
Did you have to replace all the heaters on the one separator? I know they are a wire type heater inclosed in foil and then stuck around the separator tank, but how many actually is there? Hope you can help me out? Also in regards to password on controller, i think it is 111. Hope this helps you too. Cheers.

[Magoo]

There is an ambient sensor that dictates the heaters for all and sundry in off cycle, including oil separators.
magoo

[james10]

you need to put a 24v supply to the contactor if the heaters come on you will have to replace the main prodialouge board it's quite a common fault on global chillers. also if you lose the oil due to low temps keep resetting the fault and the oil will come back if you need to add oil 1/2 litre max or you'll cause major problems with the unit and its a nigtmare getting the oil back out

[mikimakx]

Code 88 is not podhodet