sounds like nocondensables in the system. could also be if there is a txv with a schrader port for the bypass the schrader core was not removed.
sorry did not see the piston part
I have been to this call three times in ten days and cannot for the life of me figure out what the problem is, I have a three ton ruud condenser with a 100K ruud 80% furnace 1200 CFM, The complaint is not enough cooling, the house looks about the right size for a three ton unit. Filter clean, retuns not retricted, plenty of air out of vents.Gages read normal after a couple minutes of starting unit, then about ten minutes into the cycle the superheat drops like a rock along with the suction and head pressures, then after another minute or two the suction comes up fast along with the superheat and they continue to rise till the superheat reaches 60 degrees , it stays there for about two minutes and then all the readings return to normal for about ten minutes and the cycle starts again, The head also follows this cycle, I do not understand what could cause this scenario but it is causing the space to have insuffuceint cooling.
Any ideas ? Anything else I should be checking ? It is a piston system/
sounds like nocondensables in the system. could also be if there is a txv with a schrader port for the bypass the schrader core was not removed.
sorry did not see the piston part
I had a simular problem with a york. I found it to have non-
condensable in it . Removed all the charge evacuated and recharged. It ran fine. Good luck! Hopes this helps.
I thought it may have been noncondensables also , on my second call there I did dump the charge and start fresh with virgin, the same cycle repeated itself, I give up I don't know what the hell it could it be, everything looks fine, then drops, then goes sky high, then returns to normal then does the whole cyle again like clockwork.
dumping the charge wont remove non condensibles, you need to recover it, triple evacuate and recharge (virgin).
could it be an airflow issue? ifm running continuously? loose insulation in the ductwork? i'm grasping here, sounds like a strange one.
i'm assuming you did evacuate the system?
Yeah when I say Dump the charge and startwith new, I do mean all the steps. Evac properly an drecharge, I did not triple evac though, I did let it opump for almost two hours.
A couple of things with that. The Nitrogen break will help clear the system and then its not how long, but how effective the evacuation is. I would get a good read on the actual micron thing.
Superheat at 60?? I would try to measure and compare the temperatures at the in and out of the filter drier. Maybe an intermitten partial restriction.
Mr. freeze, I've seen that too.Had one with carbon crap from lots of brazing without nitro and several system openings with no filter/drier changes [did you change the drier titeless?]
Some people swear by me and some at me
It sounds like the furnace is starting during your cooling cycle. Fan shuts off, superheat down, suction p down, then suction p up with high superheat as the fan starts blowing hot air. Can't think of anything else that would cause low superheat and low suction pressure together except fan going off, then high suction with high superheat too.
Originally posted by titleless
then about ten minutes into the cycle the superheat drops like a rock along with the suction and head pressures, then after another minute or two the suction comes up fast along with the superheat and they continue to rise till the superheat reaches 60 degrees
What does the subcooling do when the pressure,s go wild ? Does your static pressure stay the same when the readings go up and down ?
Ross Kious
Speed.
Thats what it was.
Brilant, Speedracer. Now, why is the heat comming on?
Electronic thermostat? Had one this summer like that.
Beware of advice given by some guy on the Internet.
That Speed racer is one sharp tech!!!! Good call.
r404a
Thanks for the kind words guys.
What could cause the heat to cycle on every ten minutes or so while cooling is in progress, and uninterupted?
SWAG is two stats with conflicting settings, maybe cold air blowing on the heat stat.
go speedracer go!!!!!
Havin'a good time is what life is all about.
Sounds like there is something restricting the service port between the compressor discharge and the service valve, Much like pumping down the system efect?
Great call Speed,check the obvious first.Brilliant.