Original message
| Pwright
 |  "Carrier Weathermaster 48HJ series"
, posted Sun 11 May 11:44  
I am the sole HVAC/R tech at the company I work for. I have 25 carrier weathermaster package units on the roof. They are all 460v three phase. On friday night I had one of the units go down. I was unaware of this until saturday morning when I came back in to work. Upon looking at the unit I had found that the contactor for stage 1 compressor had blown off the contacts on one side. I took out and replaced all three contactors due to the fact that they all showed signs of pitting and burns. I restored power to the unit and after a few minutes the IFM came on. The T-Stat was calling for cooling, but no compressor. I then took a screwdriver and manually closed the contacts for stage one, the compressor started. The condenser fan motors did not start though. I took jumper wires and jumped R-Y2 to bring on second stage and that worked fine, except for the fact that the CFMs did not turn on still. I then took a jumper wire from R on the transformer to the coil on the condencer fan motor relay and the motors came on. I was looking on the wiring diagram and noticed that these units have a primary single phase protection. I believe that is what happened when the contactor blew up but I am unable to locate this protection device. I have an identical unit that I have taken the circut boards from to try in this unit and still nothing happens. If anyone can shed some light on this issue that would be absolutely wonderful. Thank you
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Replies:
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| theduke03
| "Re(1):Carrier Weathermaster 48HJ series" , posted Sun 11 May 12:19:
The condenser fans are powered from the Outdoor fan contactor(OFC). This contactor should be energized w/24v any time there is a call for mechanical cooling. It sounds to me like the economizer has locked out cooling either due to low ambient temps, incorrect settings, or most likely defective. You can verify this by diconnecting molex plug to economiser and jumping the blue and gray wires on system side. Some units will have a bypass plug(molex w/ blue and yellw wire) left in unit from installation that can be used to bypass economiser. Also check if dial on econ. control is set to D and if not try that.
With 25 units I've gotta believe at least one will have the plug. You can also bypass economizer by jumping Y1 to terminal 2 on CLO1. Jumper Y2 to terminal 2 on CLO2 for second stage.
"My dad was the most feared furnace fighter in Northern Indiana."
[this message was edited by theduke03 on Sun 11 May 12:26] |
| | Pwright
| "Re(2):Carrier Weathermaster 48HJ series" , posted Mon 12 May 18:47
Thanks for the info. On sunday I added a wire from Y1 to terminal 2 on CLO1. It seemed to do the trick.
Here is another good question. Today I had another unit blow a contactor. I got it fixed but I would really like to know why they are blowing up the contactors. The units did not have any service what so ever for about three years. When I was hired to do the HVAC stuff the first thing I did was a filter change, clean the coils, and check over and tighten all electrical. Now I am having problems almost every day. I was told that really the only problem they had before me was blown fuses. Any insight on to why I am having more problems now that the units are clean?
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| | mmb59
| "Re(3):Carrier Weathermaster 48HJ series" , posted Thu 5 Jun 10:24
I just stumbled on this looking for some Carrier Info - don't even know when it's from. I guarantee they had more problems before, they just didn't notice them. Keep diggin' in, keep maintainin', keep learnin', and keep the eqpt. hummin'. Real initiative is sadly, rare.
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| | theduke03
| "Re(3):Carrier Weathermaster 48HJ series" , posted Mon 12 May 19:38:
Pwright, Many thinga can cause premature contactor failure. Short cycling for any # of reasons will abuse it, high amp draw on compressor due to a dirty condenser coil may draw higher than rated amps, low supply voltage, low 24v can cause contactor to not close tightly or open and close repeatedly. coincidence is just as likely. I can tell you this for certain. A building with 25 Carrier RTU's will keep you busy all year and for many years. We just acquired a new account with 15 Carrier's all from mid 90's. I went thru them all and have a list of bad parts approximately:
2 compressors
4 heat exchangers
3 inducer assemblys
4 economizer controls
1 actuator
1 cond fan motor
3 contactors
1 CLO1
As for your question why problems now that it's clean? It's cuz you touched it or just looked at it the wrong way. No offense, the same thing happens to me. I fix what's broken and then break things that don't need fixin.
"My dad was the most feared furnace fighter in Northern Indiana."
[this message was edited by theduke03 on Mon 12 May 19:44] |
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