ReplyI have seen lower seer units run higher head pressures in extreme heat due to smaller coil surface area. I always charge using superheat if I have a piston system. IMO you need to add gas.
Professional Member
Call started off a bad compacitor then i noticed they hadnt changed there spacegaurd for a while. Got unit up and runnning and told them to leave off till i got filter next day. Replaced filter unit was running hot
Amana Rcb30c2b 10/11 seer 2.5 ton furn and a/c installed in 2004
Suc;85 @90 outside temp
Dis; 350
I Cleaned condenser which didnt seem dirty and pressures didnt change from it, also pressues and temps were fluctuating. I then reclaimed refrigerant and left nitrogen overnite
Today i was there and i took apart piston(correct size pistion) and blew everything out evacuated and recharged unit to be sure there wasnt air in the system.
95 outside
79 R/A temp 67 WB
68 supply air temp Keep in mind i didnt want to charge anymore with high head pressure fluxuating from 295-325
At 310psi 135st 115 line temp at condenser
70psi 42st 71 line temp at condenser
keep in mind my pressure and tempature readings were fluxuating as i was taking them.
Pressures should be @250 and 80 from the data sheet from unit
Regular Guest
I have seen lower seer units run higher head pressures in extreme heat due to smaller coil surface area. I always charge using superheat if I have a piston system. IMO you need to add gas.
Professional Member
What about the pressures fluctuating?
the pressures both are going up and down along with my line temps ?
Professional Member
Anyone know a list of things that would cause the fluctuating of pressures and temps
I thought non condesables,air, moisture
condenser recirculation?
condenser fan not functioning 100% (how to know)
also is a 2-3 degree difference ok on a liquid line drier?
Professional Member*
High subcool
High superheat
You have restriction.
2-3 diff is not ok on drier
Is that a new drier?
Professional Member*
Brad did you happen to add refrigerant
When you got there?
Because it look like it was low ?
A restricted drier will simulate the system being low
Did you add gas to reach 85 psi?
Restricted drier can make it fluctuate
That also mean that your system is already overcharge.
A drier should not have any temp diff across it.
Check drier by pressure drop
No more than 2 psi across.
Also u ask how would you know if the motor is functioning 100?
If the motor is not functioning 100 percent, it will probably be
Over amping and overheat
Good luck and let us know
Professional Member
I get why you wouldn't want a temp or pressure difference across a drier but how do you check pressure drop across a drier?
Professional Member
when i got there i didnt add any refrigerant It was running at 85/350 then i cleaned condenser and no difference. Although both pressures and line temps were fluctuating.
My superheat and subcooling were moving around. (fixed md). I figured air in system and let sit overnite with nitrogen. Next day i evacuated and recharched but my pressures and tempatures were moving around still. The liquid line drier is inside the condenser my temp across was 2.5 although the two probes tend to differ within a degree. I wanted to change the drier but i dint have one at the time. Pressure are fluctuating about 30psi on high side and about 10 psi on the low side so hard to say what my sh and sc reading are
Professional Member
I just checked the tempature across not sure aboout the psi unless you have a port there to check it
Professional Member*
Brad I would start by changing drier.
Bad news is you have to recover again
Install new drier outside of condenser instead
Professional Member*
Brad gall- Was your pressure temperature true, even though it may have been high. The fluctuation your may be seeing is hydraulic action through your liquid line drier. I would pump it down or remove the charge and change out he drier, go to the next size larger drier in cubic inch capacity. Verify there is no drier inside the condensing unit as most manufacturers put a bullet drier inside the unit. What I meant by true was did you pressure temperature match or was it way out of wack, this would mean non-condensibles. If pressure and temps were fairly close you are overcharged with a restriction, your drier.-GEO
Once in a while everything falls into place and I am able to move forward, most of the time it just falls all over the place and I can't go anywhere-GEO
Professional Member
Im going to and already should have Thanks so much ill let you know how it goesOriginally Posted by shaka
Professional Member
ga1279 Im going to change the drier out and yes my pressures were moving around alot which intern was changing my temp. reading as they moved around so did my temps
Thanks alot i really appreciate all the help on here since im newer to the sercive end of the business
Regular Guest
Stupid question but were you the first person there?
I live in New Jersey and have been going on call-backs from other companies and much to my dismay I have had to remove all refrigerant and TXV if applicable I am starting to really believe guys are putting the wrong refrigerants in.
I have been on two in this past week.
Sucks for the customer but when I leave the systems are running beautifully
They seem to be adding very minimal amounts but thats all it takes
Last edited by Jickracer007; 07-07-2012 at 12:05 PM. Reason: want to add
Professional Member
changed filter drier and weigh charge in still same problem any ideas?
Professional Member
ive already put new 22 in but my pressures continue to fluctuate like theres non condesables. not sur what else would cause this
Professional Member*
Brad.
Are you reusing same refrigerant from original problem
Or you change it out after u pressurize it with nitrogen
Professional Member*
What's ur pressures this time
Professional Member
new 22 I charged by weight and pressure the same as the first day I was there 85suc 350liq both fluctuating @70/85 315/350
Professional Member*
How much did u weigh in and what does name plate say?
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