I just want a cold beer!

tmk · May 24, 2005

I've been looking at a Cooler for a friend.
It's a Knight. MO:d6ost SE:39140.

This was a R12 to MP39 conversion. I repaired a leak in this system by a flare nut at the Expansion valve. When I charged the system It's almost impsible to get correct or consistant readings. no matter my charge the suction stays to low. I'm thinking the Exp. valve is bad.
Condenser Outlet Temp is 84, Head press it is 230. Sudt. press is 25, evap outlet temp is 39. My sub cooling stays pretty much the same no matter the charge.

Warm beer just isn't good!

Thanks in advance for your help.

[Edited by tmk on 05-24-2005 at 07:21 AM]

newbie223 · May 24, 2005

Looks like you over charged the unit. The head pressure is a bit high. Bring it down to around 180 and check the subcooling and the superheat again.

Wild Leg · May 24, 2005

What do you think the suction pressure should be?

len · May 24, 2005

i just want a cold beer

dump the mp 39.put frdge 12(r416a) get your back press.about 12-15lbs psi,
.head press.with this refrigerant will run a little lower

newbie223 · May 25, 2005

The unit has a TXV. You should charge by subcooling. For air-cool condensing, set the subcooling about 30 deg. I would charge it to about 185 psig and check the subcooling and then the superheat. The superheat should stay the same unless the TXV is bad. I used MP39 before, but I am using 409A now. Some units do crawl like a snail while others cool the cabinet in a short time.

tmk · May 25, 2005

Thats the thing, I can remove some ref. how ever it's like the txv doesn't compensate. My sub cooling changes by a degree or five. the suction gets to low and then starts bouncing off of low press. cont.

newbie223 · May 25, 2005

If you were suspecting the TXV is bad, recover the refrigerant and check the screen on the TXV. Replace the TXV if neccessary. Vacuum and then charge it up.

tmk · May 25, 2005

that is what I'm leaning towards, I thought I would toss my situation out there just to see if I'm looking in the right direction or if there was something else.

Thanks alot New B.

R12rules · May 26, 2005

Most TXvalves that are replaced are done so by mistake.

Inlet screen is usually clogged or power head is bad. Rarely has a valve gone totally bad to where it needs replacement.

It is just rare, not unheard of, just rare. Check other things FIRST!

Check your PT chart for what you low side should be pulling down to.

I just want a cold beer!

tmk

newbie223

Wild Leg

len

newbie223

tmk

newbie223

tmk

R12rules

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