home a/c trips out on pressure switch, when outside temps are >80

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  #1  
Old 08-21-17, 05:29 PM
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home a/c trips out on pressure switch, when outside temps are >80

hi!


this site is great!


my home a/c stopped cooling. i figured it was low on freon. i was able to get some in; it took a long time, as the pressure switch would cause the compressor to stop working within a minute or two. the inside fan and the outside condenser fan never stop. And the compressor won’t restart unless I shut off the system from the inside t-stat. now, it runs ok, but only when the temps are below 80. (and even when running, the air coming out the vents still doesn't seem to get all that chilly.) not much good that it stops working when it's actually hot outside. what should i be looking for as the problem? i have some of that a/c sealer, in case there's a tiny leak somewhere, but don't want to add it unless/until i actually figure out what the problem is with the system.


or, is it just possible that, after not running for several hours, like when i turned it on last night, that something is changing within the system somewhere, that allows it to run for 10 hours, before it shuts off? it ran for about 12 hours, before it shut down today about 2pm, when the outside temp went over 80f. then it went into the same behavior as prior - compressor shut off; outside and inside fans continue to run; compressor won’t restart until the t-stat is turned off; then back

could it still be low on freon? seems it took >5 lbs. or, could i have over-charged it? yesterday, when charging, my gages indicated ~130lbs low side and ~150 high side. seems that is way too close in pressure.



Model is 3 ton Bryant 598A; series D info on line:User manual -


dms.hvacpartners.com/docs/1009/Public/08/PDS598A.36.6.pdf


(Freon capacity should be 5.61kg, not lb; per what’s on the actual unit. And the amount listed as lbs in the pdf - 5.61 - is shown as 5.61kg on the unit, w/12.25lbs also on the unit.)


Install manual -


dms.hvacpartners.com/docs/1009/Public/04/II598A-36-7.pdf


thanks!


doug s.
 

Last edited by doug s.; 08-21-17 at 06:21 PM. Reason: correct spacing
  #2  
Old 08-22-17, 11:02 AM
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How did you determine how much refrigerant to put in ?

12 lbs. in a 3 ton unit, that can't be right.
 

Last edited by skaggsje; 08-22-17 at 11:16 AM. Reason: correction
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Old 08-22-17, 11:51 AM
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hi skaggsje,



thanks for your reply.



first off, i was reading the gauges wrong, as i had them both open. i thought i was getting pressure transfer, and another tech elsewhere said that's the case; both gauges cannot be open at the same time. either close both, or leave only one open. when i do that, i am getting 80psi low-side, 200psi high side. (today, the unit is still running and it's 87f outside at the moment.)



re: determining how much to put in. i based it on the fact that i know this unit hasn't been serviced in years, (i recently moved back in to this house after buying out my ex, and if it had been serviced, i would have seen the bill!), and its cooling has been marginal all summer, until it stopped recently altogether. so, looking up the data on the unit, which does say 12.25lbs, i used a scale to weigh the coolant, putting a little in at a time. i figured my temp/gauge readings would go to where they should be when i was getting close to the right amount. as it turns out, because i was initially trying to get readings w/the handles both gauges open, i was obviously getting bad data. :>/



but, now, as stated before, the unit is running w/80psi low side and 200psi high side at 87f. and it's cycling on-off as it should, w/t-stat set to 74f. i know the low side should be lower, and the high side should be higher; so, assuming everything else is ok, did i add too much r22 or not enough? and if the r22 amount is ok, what else could be attributing to my too-high low-side pressure, and my too-low high side pressure?



thanks!



doug s.
 
  #4  
Old 08-22-17, 03:19 PM
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Hi doug, I found the specs and it calls for 5.64 Lbs.
 
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Old 08-22-17, 04:51 PM
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Welcome to the forums.

Unfortunately the DIY admins have declared that discussing charging methods and pressures not be discussed on the DIY board as only licensed HVAC techs are allowed to charge those system. Sorry.

http://www.doityourself.com/forum/ai...ng-your-c.html

There are other sites on the web where those particulars can be discussed.
 
 

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