Replyid say pull the gas out, replace txv, while its out blow both sides out with nitrogen. make sure your pulling a DEEP vacuum
Professional Member
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
Professional Member
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.
Professional Member
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.
SDC/Educational/Membership Committee*
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
Professional Member
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!!
Educational Committee/Professional Member*
Originally Posted by mwright
You need to take sh at the evap coil as well.
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
Professional Member
So take it next to the TXV? The TXV is a bout 10" from the evap coil.
Professional Member* / ARP Committee
Any air diffusers located above the unit? Honeycombs clean?
Officially, Down for the count
YOU HAVE TO GET OFF YOUR ASS TO GET ON YOUR FEET
I know enough to know, I don't know enough
Why is it that those who complain the most contribute the least?
MONEY CAN'T BUY HAPPINESS. POVERTY CAN'T BUY ANYTHING
SDC/Educational/Membership Committee*
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.
Educational Committee/Professional Member*
Yep 6 to 8 '' from the evap coil.
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
Professional Member
Is that a typo or did you mean to say that you are measuring the temperature at the inlet to the condenser. At that point in the system, you will have superheated gas as you are supposed to, explaining your 'negative subcooling' reading.
Professional Member
How ya been, Cracker?
Professional Member
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?
Is that a typo or did you mean to say that you are measuring the temperature at the inlet to the condenser. At that point in the system, you will have superheated gas as you are supposed to, explaining your 'negative subcooling' reading.
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. :-)
Professional Member
Yes.
Measure subcooling on the outlet of the condenser, not the inlet.
What you were measuring was discharge superheat and, actually, that figure is a bit too low, IMO.
I'll be curious to see the actual subcooling.
Last edited by jpsmith1cm; 03-31-2012 at 05:11 PM. Reason: brain f**t
Professional Member
Unfortunately I won't be able to get that until Monday. I will post as soon as I do.
Professional Member
Does this thing have a Receiver and liquid line sight glass?
If so
You can forget all about that confusing subcooling
Professional Member
Yes is does have a receiver but no sight glass.
Professional Member
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.
Educational Committee/Professional Member*
Howdy jp.
How ya been, Cracker?
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
Educational Committee/Professional Member*
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'll furnish the hose.
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
Posting Permissions
