Heating, Air Conditioning, Fridge, HVAC/High Pressure Switch


Hello,I have a carrier infinity 2 ton unit 48Xl model and when I have the thermostat set for heat at 80 degrees,I get a 31-high pressure switch fault code.It seems to call for heat every 5 minutes but can not as the switch won't close properly
Sometimes it will take up to 3 days before it closes if i get lucky and heat will slowly rise over a 24 hr periodthen restarts all over again next few days.I wake up to cold 65 degree mornings and think now is time to call a repairman.Its a 2 stage system and now is set to bypass the high heat mode only operating on low but can't keep up when temps are 30 and below.when I got my gas bill it surely fluctuated running it like this with the switch open and my bill was $50 higher.My question to you is,can it be an outdated thermostat with a glitch as I have a (bryant evolution) thermostat and not the original carrier infinity but both are identical in function? The unit has seen only 2 seasons.If a thermostat can't cause this would it be something in the board? I venture to guess it can't be both as I don't know much about the things just some good advice would help me tremendously. Thank You

The high pressure switch is suppose to remain open.  When it closes, that means there is some sort of issue.  The problem can be any number of things.  Please follow the link and turn to page 22.  Granted I know it is not the same model, but this troubleshooting is the same regardless.



Heating, Air Conditioning, Fridge, HVAC

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Craig HVAC Expert


I have been in the HVAC field for the past 18 years. I can help with most HVAC questions. I work on commerical buildings for the most part, and have yet to find anything I could not troubleshoot and repair, when repairable. I work on small 1 ton units to a 2500 ton chiller. Troubleshoot air flow, elect, and control problems. I attend regular classes to keep up with the latest and greatest.


I work on commerical sites, hospitals, gov't buildings. I can troubleshoot just about anything in the HVAC business.

5 years trade school, VFD training classes, Liebert factory training, some York and Trane factory training.

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