I've posted many messages here over the years about this problem, and its been so strange I haven't been able to get it fixed. But I've confirmed that it is an intermittent problem.
24ANA7 Carrier, with a Bristol reciprocating two stage. Lo stage works great. Hi stage: almost always, supply air temp goes up 5F, hi side pressure drops about 10psig, compressor amp draw goes up about 80% (usually not quite 100%). Its been like this for years, possible since I had it installed 6 years ago.
Now, sometimes it decides to work in hi stage. Hi side pressure goes up 50+ psig , supply air temp goes down a little, compressor amp draw goes up about 100%. (not a real big difference on compressor amp draw). When I say it sometimes works - the first time I noticed it working properly this summer was Monday evening, and oddly enough its been working for 2 days. But I'm sure it will go back to its old behavior.
Last summer Carrier paid for a new TXV, 4” spacer between the blower and evap, and a new blower motor, but I’ve lost Carrier’s “interest” because their local rep moved on. (long story there)
Here is the question – does anyone know enough about those Bristol two stage compressors to render an opinion on how that could mechanically work one minute and not work the next (only hi stage). Its almost as of that 2nd cylinder doesn’t engage when it reverses direction, but then sometime does engage.
I know I really have to get a local HVAC contractor and Carrier involved, and I know about the Bristol compressor dealer service bulletin, but so far I’m not getting much traction there.