I have a Carrier 58MVP120 that was installed in 2000. The unit fails to function when the outside temperature drops into the teens or lower. The inducer motor will spin up, but no ignition will occur and the unit will spin back down, followed by a 42 error code. When the temps come up above the teens the problem does not exist. The unit is located in a crawl space. I have placed a temperature sensor there and the temps stay above 50 degrees at all times. The unit is under warranty and an authorized Carrier tech has spent about 6 hours testing the unit (3 hours on two different occasions). He did observe the problem. The thermostat is not at issue, apparently when isolated all of the components are fine. The tech has been as helpful as possible, but is as stumped as I am. I have on a few occasions placed a portable heater in the crawl space and heated it into the
60's The problem does not occur as frequently when I do this, even when the temperatures drop into the single digits outside. This would seem to indicate that somewhere there is a freezing problem, but it is unclear to me how that could occur when the temps have always been at least in the 50s in the crawl space. If the pump dealing with the condensate was malfunctioning, could this be causing the problems? Any thoughts on ways to tackle the problem would be appreciated.John