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2 Nd stage of t stats failure
I recently went to do a service call on a install on a 7.5 ton carrier pac ,unknown to myself the call was for not enough cooling in the after noon .i arrived all seemed well stat satisfied .check unit had to adjust indoor fan motor mount and belt tension ,cycled unit on and lowered stat to bring on second stage after waiting nothing went through normal bs and finally jump3d 2 Nd stage all good ,being I was just filling in advised by buddy of the issue and he stated that like every year the second stage on the stats fails. Now please take in mind that the stat wires where crap so years ago we ran new 18 gauge stat wire but the issue keeps happening every year or so ,and it’s indifferent to weather it’s a white Rodger or Honeywell stat .he also stated that it only seems to be this unit since we installed about 5 other units at the same building and not a issue but there trane roof tops . On another note we had issues w the older 30 year old carrier. I checked all I could chk and will suggest re ohming wires for possible short but I find it funny that it will work correctly for up to 9 months then go south .manual economize so that’s out of the pic ,my parter blames it on crap mim t stats .has anyone else had issues like this ,unit was replaced about 2 years ago .peace and good luck clammy
R.A. Calmbacher L.L.C. HVACNJ Master HVAC Lic.
Mahwah, NJ
Specializing in steam and hydronic heating
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Comments
I had this happen but the unit I was working on had (1) 2 speed Bristol compressor with high speed, low speed and tie contactors. I would work fine on low speed but on high it pulled in high speed and tie contactors and the stat wire couldn't handle both. Put relays in the unit so the only voltage /current going to the stat and back was rib relay coil