Tempstar, TXV, R-410a,compressor, etc problem

Sooo I went out to the Tempstar N4A360 condenser with the Internal pressure relief opening problem today. By the way, this unit is a one speed condenser motor and has NO low pressure or high pressure switch, no high temp switch or anything else. :-) Owner said it had been opening and making noise several times a day now. I unload my tools from the truck and after about 10 mins the A/C still hasnt cycled on, on its own. I went in and turned the stat down. It was set on 76 and it was 76 in the home. The unit came on and immediately I heard it running with the relief valve opened. I already had gauges on it and it was showing about 175 on the suction and about 275 on the head. I pulled the disconnect, waited about 5 secs and turned it back on. Unit ran just perfect and quietly. I checked the 11 degree subcooling and it was right on. For shits and giggles I pulled the condenser fan wire and watched the head pressure climb. About 25 seconds later with me stepping slowly backward I watched it climb to 750 psi before the relief opened. (So now you all know what they open up at). Cant quite say I want to stand near a unit that does that again. Anyways, word is that a certain batch of units may need to have the factory installed R-410a refrigerant charge removed and recharged with new virgin refrigerant. I pulled the crap out and saved it so I can do a press/temp check on it to see if it jives with the R-410a chart. (Yes, I pulled a vacuum on the tank and my recovery machine before I dumped the crap in the tank). Pulled a 500 micron vac on the system. While waiting, I found the sensing bulb on the Aspen coil was mounted horizontal at the 6 oclock position with no insulation on it. Not sure if it came that way or we mounted the bulb but that was our fuquer up. (I did the outside unit. Employee did the inside unit.) Corrected that and put it at the 4 oclock/8 oclock position and insulated it. Measured the 22 ft lineset and recharged the unit. Works fine now but time will tell if that does the trick or not?? Bubba
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If that's it... remember what I said about factory fuck-ups? :-)
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Did they say what they thought was wrong with the gas that came in it?
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Tony was at the factory and they had run out of R-410a... so, Tony told them it'd be ok to use R-22 for the time being. I guess they found out Tony was full of shit.
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It is really wierd that it would do that immediately upon startup. FWIW, I have seen factory installed TXVs with the bulb mounted in about every position you can imagine, some insulated and some not. I doubt if that is going to make much difference. With insulation the valve should actually close down a little more and give slightly higher superheat than if it was not insulated. One more thing-- we have made it standard on all 410 systems to install a sight glass-- not so much for the charge itself, but for the moisture indicator. So far all have stayed clean and green. Did you replace the drier when you recharged the unit? Well, I guess if you got it to 500 microns and it held, moisture wasn't the problem anyway. Larry
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Sight glass for R410a?? I didn't know they had them on the street yet for the higher pressures. What make/part number are you using??
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On Thu, 26 Jun 2008 00:07:50 -0500, snipped-for-privacy@webtv.net (lp13-30) wrote:

They didnt say why to change the charge but Im guessing that means there was a bad batch of factory charged units. (Thats my guess). I dont use sight glasses except on commercial stuff. Supposedly, the sight glass is not a good indicator of charge anymore on the high efficiency stuff? I didnt change the drier on the change-out of the refrigerant. Just recovered it, evacuated to 500 (which took over 2 hrs) and then recharged it. I have the old stuff and just checked it at 78 degrees. It should register 233 psi and it shows 231 psi so I think even the slightest gauge error puts that batch in the good category. I havent a clue now but I havent heard from the customer.............yet. :-) Bubba
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Is it possible the RV is intermittently sticking half way? That could create the same symptoms especially the fact that shutting off the power & back on solved it. That would be more likely if it were a 240v coil on the RV but I thought they all were 24v on the newer units. Anyways the fact that it went right into by-pass immediately makes me wonder about the RV. Either that or there's got to be a blockage in the system which pretty much goes back to the TXV. Hopefully doing what you did solved the problem by getting whatever trash was in the system. Good luck
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My bad, I forgot it was a straight air.
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