Hey all, yes im new to thsi forum... its been about 1 year since ive done any HVAC but i can still hold my own against the Koreans here who dont even know what a P/T chart is, and no EPA to yell at them when thy dump the entire charge of refrigerent from a chiller into the air! (I couldnt beleive it!)
Anyway our barraks is cooled by a Carrier Liquid Chiller. The data plate is long gone so not much is known about capacity. Anyway it died... to make it short.
heres the prob, when the unit keeps shutting down because the "Pulldown Control In Effect" wich seems seem to trigger the high pressure shutdown. One of the EXV's is broken.. it fails the self test... HVAC is not my job in the army so i hve no gauges, or thermometers, however i shall be getting a set of gauges from the Koreans here so more info later...
The main question at this point is what is a pulldown control? Like i said it been a while so if i seem like an idiot, sorry.
BTW, its like 98degrees out here.... damn it been a while.. whay did i join up??? bah...
I would have to look up the specifics, but it limits how fast the water cools - like 1 degree a minute or something.
It helps with the spikes on the electric meter and would tend the keep the head preasure lower becomes it limits how much the machine will load up.
It can be turned off on the dip switches.
I doubt that is the cause of your shut downs.
Is this air cooled ? Is the condenser clean?
it sounds like a load limiting control so when you turn the unit on and the pumps are pushing 85F water thru the chiller barrel the unit will'nt go to full tonnage.this limiter(pulldown)will rate setting will load the unit up in relation to the water temp going out of the chiller,so as the water F drops to 75F loads up...65F loads up your setpoint is most likely 42-45 sensing chilled water out to the house.if it fully loaded at start as said above high amps,head etc. possible trips due to the max'd out call for cooling.check all your condenser fans and if the coil is clean and free of garbage...if you have it running grab the liquid line and let use know what temp guess it is or take a temp reading.
I`m thinking with one of the EXV`s known to be bad, you could be limiting on evaporator low limit or condenser high limit for that circuit until you reach the trip point.Sounds like a recip or screw?
Freaking 2 condenser fans out of 6 are inop (getting them replaced) and the condenser being clean? well it is clean, but after spending 4 hours with my gerber's knife im still only 20% finised straightennin out fins... itsa not that bad, just some really crazy smashes, and names ext... but the odd thisg is that the unit was running off of the other side (good EXV) when the fans were out.... I thought maby it was the high ambient... nope it was raining and about 67-73 degrees out and i reset the unit.. code 24 (pulldown control in effect) and 55(comp 1 faiure dure to overtemp or pressure)
I see what u say a pull down control is like a load limiter, but in this case i think not. The unit did not do this before. As a load limiter i always starts off in operating mode 1 then moves up to 4(highest tonnage) But it shuts down compressor one (low tonnage compressor) dure to the bad EXV.. I found this out, on compressor 2 the pressures seem high (lowside like 120psig) and the high is close to the retard.... On comp 1 the pressures are low... Tomorrow im going out there with a P/T chart to cram some sense into the odjashe (korean male)... so ill have some hard facts soon. I appreciate the help... Were roasting here! lol and i cant gett everyone off my back.. "My AC's out carson" argg, "course it out... EVERYONES IS OUT!" lol
hope that helps
PS: hide your knowledge! Im IMO (computer tech) and resident HVAC guy now that the DIC (people in chares of housing) know and its not even my job! I love it though.
PPPS: oh here is the model number i think, its really hard to read. 30GB-045---536-- OR 306B-045---536--
Oh and how hard would it be to replace the EXV? Im gonna have to do it myself since the koreans (our DWP) here seem shade tree... i dont theink they even have a recovery unit.
Then theres GETTING the damn part.. there is no carrier dealer here in Korea.... this sucks.
[Edited by ericcarson on 08-08-2004 at 09:45 AM]
30GB CARRIER CHILLER
here is some info out of a master catalog...check inside on the panels on the line side and low voltage section they might have mod/sn sticker withinget all your condenser fans running and at full load either circuit add 30F to your ambient air entering the condenser coil and look at the inside temp ring for that freon(suction guage)and at full charge you should be around there.the fans in line with the compressor as you stand in front of the control panel should be for that circuit and no other.if the condenser looks clean it might be packed within with stuff you will see it on the liquid line as being hot a temp back to us would help.a trick to do with all the fans running on one circuit(compressor can be off for this)cut a piece of cardboard the size of one of the condenser sections portion of it not really the whole lenght...and with the fans running that should stick up onto the coils if the air is moving,if it drops or slides down the coils are packed with stuff even though they might look clean on the surface...and again this wil be reflected on the liquid line being abnormally warm to hot,and if these guys that work on it didn't purge their lines when adding freon back when that air in the system only adds to your high heads at full load.
[Edited by maxster on 08-08-2004 at 11:43 AM]
Are you sure in of the EXV are bad and not just a sensor. I have seen one to many replaced just to find out that it still did not work and that a sensor was bad. The pc bord takes readings from two sensors to determine where the expansion valve should be. If one of the sensors is bad or out of range it will not allow the valve to operate properly. If you need I can fax check out sheet to you. Also if it comes down to a bad valve be careful when ordering it. Get the Carrier part number off the valve and order it that way not by the model number of the Flowtronic Chiller. If you do it off the model number when the valve come in the plug connection on the top will most likely be wrong.
Here is a Carrier Link for the Flowtronic Chiller, should be close to what you have:
If you have a US Government Credit Card and an address that UPS or UPPS delivers to, you can get the parts shipped to you from Distribution here in USA.
Carrier has changed almost all of the Dome Style EXVs to the "new" style, so make sure the person ordering verifies the M/N & S/n with the FACTORY to get the correct valve.
Plus order a new cable and an extra O ring kit (just in case it leaks)
Also Thermistors (sensors) do fail often in the Flowtronic Chillers instead of the EXV.
Carrier will also send you the troubleshooting manual by email (PDF file) 1800CARRIER ask for a senior representative.
well heres the thing.. it this point is a budjet issue so DWP decided to leave circut1 and it messed up EXV alone, and focus on circuit2 wicj was at least functional...
After a thoural condenser powerwashing, and the replacement of the 2 inop condenserfans, the runtime before the superheat cutout engaged increased to 1 hr. The odd thing is this. (I will not mention circut1, it stsrts first then shuts off and curcuit2 engages) The low side pressure when the circuit starts is around 30psig... something like 5deg for R22... thats great! this lasts for like 10 min whille frost forms on the EXV and the tube leading into the heat esxhanger. Then sudenly the pressure rises to 60-70 wich is like 40deg! the unit stays this way indefintly. this is not suffecient to cool a 3 floor 120 man baraks! the water has only been pulled down to 70 and the units setpoint is 35
WTF? is the unit detecting an oveheated/saturated condenser? if so why no error code, cause it has one for that. hmmm.... I feel like im in school again!
PS: the EXV is bad... when the unit is put in qiuck test it attempts to open the EXV 250 steps, immeadtly it fails and the alarm light comes on. I wish i could find a damn user/instaltion manual for the damn thing.... And as for serial numbers on the EXV's? I cant see any indication of stamping/writing anywhere on them, unless their inside...
BTW: I cannot beleive the methods they use here! i saw several pounds of R22 vented like they did not even care! He must have been trying to lower the evap pressure.. I told him (i speak english, they speak Hongul, i was using a Korean soldier as a translater) to stop... the cahrge was fine! but no avail.. I have a feeling the charge is low... I HATE HAVING NO TOOLS!
30GB-045: This is a 45 ton Carrier Flowtronic Chiller.
When pull down control is in effect, the unit will not load up anymore if the water temp is dropping more than 1 deg a minute.
You MUST get a copy of the microcontrols literature in order to work on this unit!... Call a Carrier rep and get them to Email you a PDF file.
Check to make sure the cable to the EXV has no loose connections at the motherboard. Unplug the plug and ohm out the windings. You will have 1 common and 3 or 4 hot wires to the motor windings. Those plugs are known to have loose connections because the wire pushes into a knife which pierces the insulation (like a telephone line connection).
You can pump down these units by closing the liq line service valve and running the compressor until the pressure drops to about 10 PSI...no need for a recovery unit.
Well the pulldown control does not trigger anymore.. its just sits there running at partial capacity...
And there are no carrier reps here in Korea... all the ac here is manufactuired by LG
It seems that a lcak of ventilation in the comperssor section was causing a thermosensor mis reading, especially the condenser, wich caused the exv to throttle back.... I also think its still undercharged... but i can only suggest, not act.