Hvac blower problem

[Helloball]

My 95’ 525i manual hvac control is getting on my last nerve. My fan only worked on high #4 so I replaced the resistor. Now it acts even dumber. No fan at all through the ascension scale on knob. No fan until #3 and 4 speed. When descending it sometimes works on #3,2,1 but there is about a 10 second delay before it starts running. Rarely does it work on #1 wether ascending or descending and never runs when in the ramping part of the dial. Could it be a bad resistor or someone other unGodly expensive stupid problem. I hate to gripe but bmw hvac systems suck. I feel I have the right to say this bc i also own an 89’750il so I have experience with bmw and their shitty electronically controlled everything. I know someone’s going to jump my ass for this but any bmw owner knows I’m justified in what I’m venting about. Anyway changing out the resistor didn’t fix it but thicken the plot. Thnx for your help in advance.

[E34 Lives]

You sound like you are mechanically inclined and we can all agree, it is a pain to do HVAC. This can probably be done over a weekend.

Rebuilding the HVAC in your situation sounds more like the blower motor is on its way out. There are many options for parts and even FCP has a reasonably priced OE part option.

The resistor is a very simple part, bunch of coils of various thickness to vary the current to motor. The old resistor being worn out might have contributed to the fan motor strange operation and damage over time, setting 4 is the max and bypasses the resistor, if that fails then a new blower is need for replacement, given the electrical part is 27 years old, replacement might be a wise choice given its age since the blower has been exhibiting the in ability to move at lower resistance, which mean the motor can not spin or register the lower current resistance or sensitivity.

Going from 4 to lower modes work because it is spinning from the higher setting and the momentum allow for 3 or 2 setting to continue the spin, until it comes to complete standstill when it is shut off, then it needs another kick start from setting 4. That motor is exhibiting overheating characteristics and is going to overheat if left in low setting without spinning, so potential fire hazard if there is leaf and kindling debris mixed in with hot or over heating motor.

Time to replace blower motor. If your AC is running cold then you are ahead of the game. I have a 1995 540i with over 210K miles and the original AC is still cold, resistor and motor still works, but I will pick up a resistor and motor as it is just a matter of time before they will require replacement either for functionality or safety ….. maintenance is needed.

Keep in mind, inside engine are the Heater Control Valve 64118391417 and Auxiliary Water Pump 64118390063 and their respective hoses that is part of the heater system. I have replace both with new units and upgraded silicon hoses. So doing a little at a time will chip away at the maintenance, DYI is a must, as I can’t phantom paying someone to do this, it would not be cost justifiable with added labor cost.

Happy Wrenching, Best of Luck on this project!

[Helloball]

So how hard is it to get to and replace the fan? I know it’s going to be loads of fun!

[Helloball]

I found a video on it. Looks like 6.5-7 out of 10 on scale of difficulty. So much fun.��

[moroza]

With IHKR at least, the blower is a purely analog system, no electronic control whatsoever. E34 Lives' diagnosis is likely correct, but another possibility is bad contacts. Based on your location in the Rust Belt, I'm going to guess the contacts at the blower motor itself are corroded, fixing which involves the same labor as replacing the motor, which I would at least remove and inspect if not replace outright. The problem with outright replacement is that AFAIK, all aftermarket fans are mainland Chinese, with everything that comes with. If yours passes inspection, I'd leave it alone or just replace the brushes. It's not a bad job, perhaps two hours if you can turn a wrench and haven't done it before. On a scale of difficulty I'd put it at a 3 or so. Beware of brittle plastic when releasing the straps holding the blower motor cover, and the motor itself.

If you're willing to do more involved work for long-term benefit, consider upgrading the fan wiring WIT.

I generally agree with the complaints about too many electronics, but when it comes to the E34, I find its climate controls (if not their execution) perfect - individual sliders for all vents, two-zone temperature control, optional stratified temperature, analog fan. Compared to a temperamental button-fest like most newer BMW, it's refreshingly straightforward.

[shogun]

this might help, how to access the blower motor http://www.nmia.com/~dgnrg/page_15.htm

[Helloball]

Thnx guys