Does the transformer power run thru the limit circuit before it gets to terminal strip?? If limit circuit fault (code 33) then u must have an open switch somewhere. That's where I would start anyway.
I had a call last week where I found a Carrier 8000 furnance with error code 33 Limit circuit fault. The Carrier t-stat had no display. I checked for power on terminal strip on board and no 24v on any terminals. I assumed the board was faulty and I replaced today, just to end up with the same result. Should there not be power off my terminal strip to at least power t-stat? I have no power from r,g,c etc to ground, but the blower runs. I checked the fuse and it checks out.
Does the transformer power run thru the limit circuit before it gets to terminal strip?? If limit circuit fault (code 33) then u must have an open switch somewhere. That's where I would start anyway.
Transformer 24V goes straight to board, If even say a high limit was open would that break power to t-stat?
I'm not familiar with that particular board, just asking if the power did in fact get interrupted by the limit?? Its not normally the case, but wasn't sure on that 2 stage board. Its clearly something exterior of the board, unless u got a bad new one. Are you getting the same error code with new board installed??
Says 33 is limit circuit fault. And blower runs. I think u have an open limit somewhere, like the code said. Did u check all the limits and rollouts for continuity. ?? I think u may have replaced a good board
No I didnt check all the limits for contintuity, I suppose you guys may be right it is possible I replaced a board that was working. What I dont understand is that if the transformer sends 24v straight to the board and not through the safeties first why would I not have power at my terminal strip and power at t-stat. It seems odd that for example during normal operation a limit opens why would as a part of this safety circuit power is disabled on my terminal strip on board and take the t-stat out of play, or maybe for all I know this is normal?
Are you saying that you have voltage at the T-stat, but not at the control board?
No power at t-stat, power on control board, but no power at terminal strip that is on control board. By the way an error 33 is an limit circuit fault which indicates a limit or rollout open and if open switch does not remake within 3 minutes than code changes to errror 13(which i did see occur)
Well i guess I screwed this one up, checked my safeties and the high limit was open, for some odd reason the stat is wired in series with the safeties and when any open you lose power to stat.
Good u got it going. Odd stat pwr is run thru limits. State powered thru furnace, no battery backup. ??
No battery back up, stat powered by common thans for the help