id say pull the gas out, replace txv, while its out blow both sides out with nitrogen. make sure your pulling a DEEP vacuum
Freezing starts at TXV and continues to the evap coil. 404ALow side is 43.2. High side is 323. SH is 20SC is -45. 5.12 amps on run wire from compressor. Do you think I have a restriction in the TXV or am I low on 404?I have evacuated this thing twice and put in 64oz as specs say. It ran fine for about 3 weeks then started freezing up. Any help is greatly appropriated. Thanks
id say pull the gas out, replace txv, while its out blow both sides out with nitrogen. make sure your pulling a DEEP vacuum
You can't kiss death without it kissing you back. Death is a passionate kisser.
I agree with the TXV. The high discharge pressure is an issue too though. You didn't mention concern over that, but check that condenser and clean it good. POE oil doesn't fare well to a high side running hot.
Post the model number of the case and we'll have a much better chance of helping you.
Where were you measuring the superheat? At the evaporator outlet or at the compressor? A 20ºF SH might be OK at the compressor but way too high at the evap outlet.
Did you say 45ºF subcooling? That's too high, but may be explainable if your evaporator SH is high as well...and there's no receiver.
The Federal cases I've seen are control temperature by a low pressure control, typically set at around 42#CO/85#CI for R404A and defrost is controlled by a mechanical timeclock. I'd start by verifying these items' operation along with proper SH before condemning the TXV.
Do you have the manual? Here's Federal's manuals page:
http://www.federalind.com/index.php?...ls-parts-lists
Yes I do have the manual thank you
Model is SC478
SC Temp is Negative 45 not positive 45
Measuring SH next to compressor so yes 20 is not bad. Measuring SC just before the condenser coil.
I am concerned about the high pressure on the high side sorry I don't mention it.
Also pressure setting are set to the manual which are 42 & 82. I was thinking maybe the pressure switch was bad because it will come on then the low side pressure will drop fast but not low enough to shut it off according to set pressure but it will shut down.
Thanks for all the help!!
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Any air diffusers located above the unit? Honeycombs clean?
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For evaporator superheat you need to measure the temperature at the outlet end of the coil where the TXV bulb is attached.
For subcooling, you need to measure the temperature at the outlet of the condenser coil.
There is no such thing as negative subcooling. It sounds like you were measuring the discharge line temperature, not the liquid line.
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Yes between the compressor and the condenser coil but closer to the coil. Am I supposed to Benin the other side of the coil, the output side?
Incase you haven't figured it out I'm new to this and I appreciate all the help. Where I work doesn't have anyone with the time to train me so I'm digging in and learning as I go. :-)
Last edited by jpsmith1cm; 03-31-2012 at 05:11 PM. Reason: brain f**t
Does this thing have a Receiver and liquid line sight glass?
If so
You can forget all about that confusing subcooling
Yes is does have a receiver but no sight glass.
Install one.
Once you put a receiver on a system, you don't need to worry about subcooling, you need to worry about a clear sightglass.
My mistake for not catching this earlier. I'm switching to AC mode and subcooling is part and parcel of that.
I'll take myself out back and whip myself 25 times with a refrigerant hose, now.
I love the smell of phosgene first thing in the morning:
To apply for professional membership click here
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I love the smell of phosgene first thing in the morning:
To apply for professional membership click here
Educational forums are open.
If you would like to submit a link or an article or other related info to the EF. click here