1998 BMW 740 no hot air.

Is there any air at all? No air from the vents could mean a fan failure, no hot air could be a failed heater valve. Does the IHKA work normally other than the fan? (IHKA is BMW speak for heating/air conditioning)

Dr. Hagerty, Dr. Loot here:
I have the same problem with one of my patients a 1998 BMW 740I with 98,000 miles,
I get hot air out of the driver side, but cold air out of the passenger side, my wife is freezing her *@#! off, any suggestions?

Indeed, check the heater valve. Also there is a possibility that there is a stuck blend door or a failed actuator for said door. The IHKA is connected to a communication BUS and if there is a fault set, then it will be recorded as such. A GT-1 is almost a necessity for this job, if you dont have access to one, this could become a very long repair process. Also, dont forget to check the basics, I dont know how many times I got stung on a poor ground or a blown fuse, do you know what I am saying?

I am not sure what a "A GT-1" is, I do have a snap on scanner, but only with the genetic cards, the car hit a fire hydrant in the front right, I will check the grounds and get back to you thanks, and thanks for your support!

The GT-1 is the proprietary diagnostic device used at the dealer and is available in a cloned form so it will run on a laptop. It can report on status of the IHKA sensors and parameter percentages. It can also perform component activation. If you work on BMW's you need one and training on how to use it.