Replyrestriction in 1 or more distributor cap tubes?
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Hopefully the picture I took of the DRSA is adequate to provide all refrigerant side data.
Problem is this:
Dual temp single deck case would NOT hold temp in LT mode. Did a 'fair' job in MT.
Tech#1 was out and condemned the powerhead and when that did nothing, replaced the whole TXV. When THAT didn't work, I was called in.
Cut in a pressure tap and SG on the liquid line to confirm quality of liquid and the pic I posted gives the results. Sightglass was perfectly solid.
So. Fire away.
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restriction in 1 or more distributor cap tubes?
Professional Member*
Seeing as how I am a former resi guy and new to the refer tech gig, I'm
going to take baby steps on this one....
Am I correct in thinking that suction PSI is too low?
(or do I need to head back to class?)
I need a new signature.....
Professional Member*
I was thinking the same. Maybe the nozzle is plugged. Or possibly a plugged external equalizer line for the txv...Originally Posted by air2spare
Last edited by dangpgt97; 12-05-2010 at 10:31 PM.
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What type of txv ? is their an EPR to tell the system if it's MED or LT? I have seen some with a solenoid by pass.
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Liquid line drier in case was partially plugged, S.G. was cut in before drier??
What are the components in each case?
Suction line solenoid with 90 degree EPR for MT operation?
Watts New, Ohm My, I been Electrically Commutated. Are U2.
Professional Member
CRO valve not set correctly or switchover solenoid not working properly
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Externally equalized Sporlan BQ type TXV. Orifice if properly sized.
Forgot to add that Tech#1 replaced case drier. SG was installed after drier anyway.
Pressures taken at coil, upstream of DT solenoid/ORIT valve.
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Even frost pattern on all tubes. Took the nozzle out and inspected. All clean and clear.
Actually, the suction pressure is a wee bit high, but not terribly so. The case MFR calls for -22 degrees SST.
I even replaced the external eq line to no effect.
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This was a tough problem.
I had to bring in factory support and he made it so simple that I felt like an idiot.
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Is the txv adjustable. If so. Open it up a few turns
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hmmmmmmmmmmmm. Is this an open air case where a heat duct or something could be disrupting the air curtain?
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Factory styrofoam peice at top behind discharge honeycomb was too big, (cut on wrong angle)blocking majority of airflow.
Found this on several Hill end bunks at same store.
Watts New, Ohm My, I been Electrically Commutated. Are U2.
Professional Member
TXV was wide open at the time this picture was taken.
All heating vents were already checked and aimed away from this case. (Yes, it is an open air single-deck type case)
Not to be a jerk, mccool, but how would low airflow contribute to this problem?
Ok. Time for another hint. It hasn't worked right in a very long time if it ever worked right. Our company didn't install it, but we got saddled with the repairs.
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What kind of defrost. If electric. Are the heaters on during cool?
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Excellent question.
The heaters weren't on.
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Ok my last guess.
Is the compressor correct for the application?
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Compressor inefficient?
Member
If the air curtain is ok and this is on a low temp rack Is it the longest run ? How is the case nexted to it ? I had two bunkers side by side and one would take ref from the case that would not maintain temp the case that was working was the problem I think I got gray hair from that job.
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There is an *assumption* being made and it is the SAME one that my tech made, that I made and that the other tech that I called for advise made.
As I said, the factory guy got it in about 5 seconds. Made me feel about 3 feet tall.
I actually think that a residential AC guy would have nailed it a lot faster than I did. From what I've read, those guys see problems like this more often than I do.
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