carrier fault code 33 on 58mvc
have fault code 33 on carrier mvc, works fine in high fire, ran fine for 10 minutes each in low and medium fire through the check out in infinity controller. brand new infinity air purifier filter installed in november and is clean, all gas pressures are in range when tested and temperature rises in all 3 stages are good. anyone with a possible solution or something i missed would be appreciated. i am in the business and have installed many of these furnaces without trouble.