Bmw 523i se heater blows hot and cold. Sounds like a thermostat sticking. Some things to do. First check coolant level is up and moving. Second (most likely), change thermostat. Very easy fix for backyard mechanic. Make sure to put thermostat in so water flow is correct direction. BamaF10. 40 posts · Joined 2016. #5 · Jul 23, 2016. your blower motor is likely going bad. If the noise stops when you turn the fan off, then it's 99% chance something is wrong with blower motor or the wiring harness that connects it. I had an issue with corrosion on both my front and back blower motor harnesses (I have 4 zone HVAC) and it 2001 bmw x5: 4.1 sport my front blower does not blow any air i have a 2001 bmw x5 4.1 sport my front blower does not blow any air out of the front vents the rear vent is ok … read more Need a few more of those details. If when you manually set only one zone (top, middle, bottom) to on, the rest do not blow any air, then it would seem your flaps are functioning correctly. If this isn't the case then it warrants a closer look. You can use INPA, Carly, or similar to scan for codes on the KLIMA module. 1. Heater doesn’t work. One of the first symptoms of a faulty heater control valve is a heater that fails to produce warm air. If the heater control valve breaks or gets stuck, the coolant flow to the heater core may be restricted or stopped completely. Without coolant flow to the heater core, the heater will not be able to produce warm air Reasons a Cadillac Escalade AC Isn't Working. Cadillac Escalade. The most common reasons a Cadillac Escalade ac isn't working are a refrigerant leak, an electrical climate control issue, or a problem with the air conditioning compressor. 0 %. The most common causes for AC blowing hot air in BMW X5 are low or overcharged refrigerant, compressor malfunction, dirty condenser or evaporator coils, faulty blend door actuator, defective evaporator temperature sensor, bad AC pressure sensor, and bad fuse or relay. Less common causes are clogged expansion valve or orifice tube, overcharged FlyingAMT. 21 posts · Joined 2016. #9 · Jul 23, 2021. I'm having the Same issue, Warm on the Drivers side only, the Passengers and back seat are plenty cold. The same compressor services everything, so it has to be a blend door or something else allowing warm air to mix on the driver's side. Jerandlaur and Nail Grease. VjBnp5.