Fan not working when put on heater

Hi,

When you say the fan stops working, I assume you are talking about the blower motor or fan for the HVAC system, not the engine fan, correct?

When the air conditioning is on the fan motor blows on high as soon as you switch it over to heat it quit the fan motor inside the car and stops blowing heat. but you put the blower down to medium and the heat will start again but it it's not enough to clean the ice in the winter time when the winter comes this year.

Okay, unless one of the in car temperature sensors is giving the control module bad information then I suspect the control module is the issue.

There are no resistors (technically this is the resistor) or other controls of the fan other than then control module. It does not seem likely that the sensor reading improperly would cause only high heat to be offline. This seems more likely to be a control issue.

Clearly not something we need to guess on because they are not the cheapest components. Looks like they range from $50.00 to $200.00. so we need to monitor its output with a scan tool. We need to see if it is commanding it off or not. I suspect it is not which would tell me that the driver in the module has failed. Hopefully you have access to a scan tool and we can go from there. Also, there could be a code in the system for this so we need to check that as well.

As usual thank you very very much you've been a great help.