Walk in freezer
i am working on walking freezer
which was not running
faulty starting component
ran unit it trip on low pressure switch.
frost on txv and distributor tubing
h.p 350 l.p 25# amb. temp 95*-100
l.p rises when not operating. l.l solenoid faulty
Replace l.l valve and filter drier . Recover (404a) freon
flush system after disconnecting txv w/dry nitrogen lots of oil came out of distributor tubing pull vacuum, break vacuum w/dry nitrogen 5# and again pull vacuum for 4 hrs. charged unit h.p 225 l.p25# box temp after 1 hr 53* frost still building on txv outlet and distributor. i am suspecting system is contaminated any idea what is going on my next step is to replace txv valve before doing that i wanna mke sure syetem is clean. is ther a way to check the system w/out opening.
any assistance or advice will be greatly appreciated
charged unit h.p 225 l.p25# box temp after 1 hr 53* frost still building on txv outlet and distributor. i am suspecting system is contaminated any idea what is going on my next step is to replace txv valve before doing that i wanna mke sure syetem is clean. is ther a way to check the system
With the number you show, it looked pretty good to me, maybe a little under charge. Frosting is normal.
What is your sub cooling? ________ super heat? _________
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I almost gave up but next day i went back turned off the evap fan i see frost building up which gives me idea that that evap was not flashing gas because of fan running so i try looking for DTFD it was fried ireplaced DTFD unit went down to -5* so that was the problem thanks
Originally Posted by Qamar
I don't understand
None of it make any sense to me.
I think there is something you are not telling us.
Box don't get cold enough but when you replace termination fan delay
The box drop?
When u turn off the fan you had an idea?
It's not flashing gas?
Let me guess
You are working on your own equipment.
You don't want to call the tech back ( too expensive)
So you will fix it yourself.
Defrost heaters on ?
Replace enough parts and just maybe you will get lucky.
Originally Posted by shaka
it is tied to the WALKING COOLER
I came this far after 32 or 33 threads I accumulated enough info to understand operation of Walking freezer .And this acquired knowledge help me to troubleshoot in systematic fashion which help to pinpoint the problem. W/20*F box temp i Did'nt see any frost on back wall of evap. after turning off fan i see frost building across the coil which led me to check defrost t/stat which was defective i replace it turn on the unit temprature start dropping. There are people in this wrld who value ur effort this cstmr is one of them.
Will work for knowledge
Why do you think it's contaminated when you tell us you pulled the charge and vacuumed everything? Assuming you charged as a liquid.... Without any temps other than your pressures it would seem to me you have a restriction. Would be helpful to have a superheat number to know what the expansion valve is doing. If you have a receiver then I wouldn't worry about subcooling. Superheat would be anywhere from 6-10 for my taste but maintaining your 20 degree compressor superheat. Taking a superheat reading I bet will point you the right direction.
Not a lot to go on here, but I would pump it down and check and clean the tx screen... Could have a weak power head too.
check txv screen it's clean turn off avap.fan to see flow of refrigerant , frost was building all across evap coil follow sporlan instructions to adjust SH left unit running all night chk next morning box temp went down to 20*F. 1/4 turn stem to chk if it goes down further. I am debating if there is a mismatch. I have collected all the info.will do a serious anylisis.
Obviously I'm a little behind the curve on replying here, but if you adjusted SH via Sporlan instructions - what did your final superheat reading come in at?
Originally Posted by Qamar
Furthermore, when you started working on the unit the outside ambient was ~100F and head pressure was 350 psig - giving you an almost 30F condenser TD......which ain't right.
After changing the LL solenoid valve, you stated the head pressure was reading 225 psig. What was the outside ambient?
A guy shouldn't be horkin' around with the TXV until he's darn sure he has enough gas in the system....
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If what you are describing is what I think you are. 1-very low suction pressure yet head pressure is normal or maybe a bit high? It sounds like you've done a good job cleaning up the system. Evacuating and putting the proper charge in. You've replaced the drier and the liquid line solenoid, correct?
I would suspect that possibility that the power head assembly has lost it's charge which would shut off the expansion valve. Just a thought. I've had many powerhead's lose their bulb charge and it has some of the symptoms you've described. Also you can have a wax build-up that can plug up the txv. But again, you've cleaned up the system which should have taken care of that possible problem.
Hope this might help.
Thanks all of you guys for advice iam going there today I wil remember 3. things for sure They must be fit for it. They must not do too much of it. And they must have a sense of success in it