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  1. #1
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    Nov 2011
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    Carrier 20 ton unloader action backwards

    I know this is a long post but any help is much appreciated, Im working on this unit Name:  01.jpg
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Size:  46.6 KB We changed the compressor last week due to mechanical failure, pulled a vacuum overnight, and charged the next morning to what i thought was 10-13 SH and 0 SC (I found out today my brand new fluke meter was reading 10 degrees higher than my buddys same model brand new fluke meter with the same temp clamp, so now im not sure if i had 0 SH and 10 sC, and my infared was reading the same as his meter so hell if i know) Anyway when i charged it, the compressor was loaded and both CFMs were running. it ran for a few days as far as i know and went down saturday, we went back monday and found the control transformer blown, a 6 amp high voltage fuse for the tformer blown, and a low voltage fuse tripped. We got it all ready to go again and found the smoke detector pulling 7.5 amps, so we unwired it, then found the contactor pulling 5.4 amps (new contactor with compressor) changed the contactor and got it where it would run. When we brought the comp on it sounded like it was going to come apart, like liquid refrigerant had migrated into the compressor. we turned it off and checked some things and noticed the crankcase heater was not working( this is the second replacement compressor in this system) 3 total. so we brought it on again and it started to quiet down so we ran it for about 10 to 15 minutes when we noticed the head with the unloader was Extremely, like 300 degrees hot. we turned it off and noticed the oil sightglass was empty( yes the compressor was shipped with oil, and before we started it after we fixed the short the sight glass was full im guessing with mostly liquid refrigerant) so we got the boss involved he came out and wanted to run it, so we did it started up good but after some run time the head was getting HOt again, we decided to jump y1 and y2 to load the compressor when i did it was Bad , amp draw jump to 55 from 28 and sounded like it was going to come on out of the condenser. We turned it off immediately!! We returned today and found this when we took the head and valve plate offName:  IMG_2370.jpg
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    The gasket is obviously not in tact, not sure if it was that way from the factory or not, looking at the marking on the valve plate after we took the gasket off. anyway we took the old metal gasket off of the old head and slapped it on pulled in vac and charged. Started up and ran, good oil level in sight glass, head not getting very hot, looking good.... Well we thought the compressor was not loaded, we did not have a call to y2 and we jumped it out and suction psi went up? amp draw went down from 26 to 17? took jumper off and amp draw went back up and ext. Like the unloder is doing the opposite of what it should, i know they have diffrent types of unloaders but this was the original unloaderName:  IMG_1340.jpg
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Size:  42.6 KB Any ideas of why this would happen, and by the way we have a crankcase heater coming tomarrow
    Last edited by david912; 12-05-2012 at 11:36 PM.

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