Climate Control Fans Fluctuating

[legobumb]

Hello all,

I am brand spanking new to the world of BMW, as I have recently purchased myself a fully loaded 2002 BMW 325xi from a private party. I knew going into it, it would need some TLC since it had ~203,000 miles on it.

Aside from interior upholstery needing to be tidied up (some of it's hanging loose or small bits of it are missing) and cleaned, I noticed the climate control fans fluctuate at all levels of power, from maximum heat to maximum A/C cold. To put it more simply, the fans are constantly going up and down in speed as if they aren't getting a steady stream of electricity going to them for some reason. I'd like to know if anyone is familiar with this problem, and how they fixed it. If no one is, I'd like to know what the best steps are to take at diagnosing the issue. Please note: I am not a professional mechanic, but I do a lot of mechanical work myself as much as possible as problems show themselves.

For those who want a short history of what I did to the car shortly after purchasing it...
1) Transmission fluid change (Castrol Transmax Dexron VI)
2) Front differential fluid change (Valvoline 75W-90)
3) Oil change (Mobile 1 High Mileage Synthetic 5W-30)
4) New lifetime warranty water pump (? Duralast ?)
-> Car has Prestone 50/50 Coolant already in it, so I replaced what came out with that
5) New brake pads on all 4 wheels
6) New front brake rotors

Things still to get done
1) Rear differential fluid change
2) Swap out these stupid-ass coil-over stiff-as-fuck slammed-to-the-ground shocks (trade for OEM shocks with someone? )
3) New tires
4) Fix upholstery (somehow)
5) Fix fan fluctuation issue mentioned above
6) Replace front driver-side CV Axle since the rubber boot on the transmission side of the axle is completely torn off and I don't trust it (I noticed when I did the brake pads/rotors on that area)
7) Replace rear brake rotors
8) Replace rear brake calipers and pistons (those things are rusted/rotted to all sorts of shit; FAR worse than the front brake calipers; worse than my 1999 Cavalier)
9) Get a new splash guard for the engine compartment (it's missing completely from what I can tell; I don't think it should be exposed on this car)
10) Fix these god-forsaken halo lights and HID headlights/high-beams the previous owner installed because they don't sit still whatsoever (and need to be aligned)
11) And lastly, clean the leather! I kind of started this, but this shit's so old and worn, I might have to get it professionally restored or some shit.

Apart from that lovely to-do list, everything engine-wise functions like it's only got 50,000 miles on it. The head gasket was already replaced at about 199,000 miles. The car feels smooth when I'm not dodging every little fucking pothole in the road. Going from ~120HP Cavalier to a ~190-200HP BMW is a huge difference for me. But as of right now, I need to save a little money for the more important things like the CV axle ASAP, the rear differential fluid change, and some new tires. I figured I could at least get the climate control fan fluctuation at least diagnosed while I'm at it.

Thanks for reading!

[All2kool]

I figured I could at least get the climate control fan fluctuation at least diagnosed while I'm at it.

Final Stage Resistor (FSR) needs replacing. Not an expensive part (Behr/Hella brand). I just did this job myself. Not technically challenging but it is an ergonomic challenge. If you're a big fat guy with large hands, it will be even more of a challenge. Several YouTube videos show the replacement procedure.

[legobumb]

Cheers, mate. I greatly appreciate the information. It seems like a really quick fix, too.

Autozone: $71.99 Santech https://www.autozone.com/cooling-hea...58825_193023_0
Advance Auto Parts: $51.23 Metrix https://shop.advanceautoparts.com/p/...019%7CL3*15900
O'Reilly Auto Parts: $128.99 BWD 5 Bullet https://www.oreillyauto.com/detail/b...q=blower+motor
CarID: $35.42 URO (with shipping) https://www.carid.com/uro-parts/hvac...leid=327998007
CarID: $39.84 Behr (with shipping) https://www.carid.com/behr/blower-re...leid=892314895

I definitely cannot afford the O'Reilly price-gouging on a seemingly simple part. With CarID offering the lowest of them all with those 2 specific brands (your suggestion included), is there any reason to NOT get the URO branded FSR? I know there's only a $4.42 difference, but I'd like to get as many facts as possible before throwing money down on electrical parts.

As a side note - who would really buy this part for well over $100? O'Reilly even had one for over $300. That shit better make me a damn good cup of hot chocolate, or at least pour me a shot of whiskey for that much money.

[MarcoZandrini]

Please do not put cheeep aftermarket cooling system parts in the car. Why? They’ll fail very quickly and leave you with an overheated engine. Modern BMW engines are made of aluminum and do not tolerate overheating. As a result, the only way to fix an overheated engine is to replace it with a used engine. At that mileage the entire cooling system needs to be overhauled. That includes:
- all hoses
- water pump
- thermostat
- expansion tank & cap
- expansion tank bracket
- radiator
- lower radiator temperature sensor o-ring
- fan clutch (automatic transmission only)

Buy these parts from a reputable vendor such as fcpeuro or ECS Tuning. I personally prefer fcpeuro as the company provides s lifetime warranty on all parts. Now, fcpeuro will show you 3 or more parts for each of the above. Go with the parts that are made by the suppliers to BMW. But don’t buy BMW branded parts as they are over the top expensive.

Also, the only oil you want to put in that engine is oil that has BMW LL01 on the label. The 5W-30 is too thin. The only Mobil 1 oil that used to meet BMW standards was 0W-40. The only brands if filters that you should by are Mann, Mahle or Hengst. Why? Aftermarket oil filters have a tendency of falling apart.

off the soapbox.

[All2kool]

As a side note - who would really buy this part for well over $100?.

The FSR is one of those parts that isn't rocket science and will last for over 100K miles. I spent $20 for a new one.

https://www.ebay.com/itm/BMW-Blower-...Namu3h&vxp=mtr

[legobumb]

Please do not put cheeep aftermarket cooling system parts in the car. Why? They’ll fail very quickly and leave you with an overheated engine. Modern BMW engines are made of aluminum and do not tolerate overheating. As a result, the only way to fix an overheated engine is to replace it with a used engine. At that mileage the entire cooling system needs to be overhauled. That includes:
- all hoses
- water pump
- thermostat
- expansion tank & cap
- expansion tank bracket
- radiator
- lower radiator temperature sensor o-ring
- fan clutch (automatic transmission only)

Buy these parts from a reputable vendor such as fcpeuro or ECS Tuning. I personally prefer fcpeuro as the company provides s lifetime warranty on all parts. Now, fcpeuro will show you 3 or more parts for each of the above. Go with the parts that are made by the suppliers to BMW. But don’t buy BMW branded parts as they are over the top expensive.

Good news! No fan clutch! 5-speed manual <3

I used a high quality Water Pump from what I can tell. Came with it's own O-ring and has a lifetime warranty and everything. I inspected the inside and outside of the expansion tank and found no dirt/grime/sludge or anything. It looked fairly brand new. And when I did the water pump and bled the system, none of the coolant that came out was dirty or discolored or anything. I haven't gotten a chance to glance over the radiator all that well (I could have when I did the water pump, but I didn't think about it). I remember taking off the upper hose (the one going from engine to expansion tank) and cleaning it out because I broke off the bleeder screw in there by accident (Don't worry! I got it all out before turning on the engine!). Neat design BMW has there, with the clips and everything. I'm used to those horrible clamps.

I'll look into getting a new o-ring for the sensor on the lower line a bit later. The engine has done no overheating since I did the water pump and bled the system. So it's not a PRESSING matter at this point in time. I'm moreso concerned with replacing the front driver side CV axle and trying to get some OEM shocks/struts all around so I don't have to worry about a single pothole possible rattling my new BMW to pieces, popping the tires, or slamming my nuts on the seat. Either way, thanks for all the info!

I'm getting a CV axle and differential seal from Autozone tomorrow. Then I'll get that Behr FSR off eBay recommended by All2kool.

Also, the only oil you want to put in that engine is oil that has BMW LL01 on the label. The 5W-30 is too thin. The only Mobil 1 oil that used to meet BMW standards was 0W-40. The only brands if filters that you should by are Mann, Mahle or Hengst. Why? Aftermarket oil filters have a tendency of falling apart.

off the soapbox.

Literally, the owner's manual says to use either 5W-30 or 5W-40 dependant on the temperature range in my region. New England doesn't get so extreme to warrant a need for 5W-40. In terms of what kind of oil to use, I looked at the bottle and it says it "meets or exceeds the requirements of API SN/SM" which I remember reading somewhere is what E46's like. I did not find a single oil bottle saying anything with "LL01" on the front/back anywhere (Autozone, Advance Auto, Walmart, etc). I'd probably have to order that online or go directly to BMW (who is actually right down the road from me, coincidentally lol).

[Jackson42]

Good news! No fan clutch! 5-speed manual <3

I used a high quality Water Pump from what I can tell. Came with it's own O-ring and has a lifetime warranty and everything. I inspected the inside and outside of the expansion tank and found no dirt/grime/sludge or anything. It looked fairly brand new. And when I did the water pump and bled the system, none of the coolant that came out was dirty or discolored or anything. I haven't gotten a chance to glance over the radiator all that well (I could have when I did the water pump, but I didn't think about it). I remember taking off the upper hose (the one going from engine to expansion tank) and cleaning it out because I broke off the bleeder screw in there by accident (Don't worry! I got it all out before turning on the engine!). Neat design BMW has there, with the clips and everything. I'm used to those horrible clamps.

I'll look into getting a new o-ring for the sensor on the lower line a bit later. The engine has done no overheating since I did the water pump and bled the system. So it's not a PRESSING matter at this point in time. I'm moreso concerned with replacing the front driver side CV axle and trying to get some OEM shocks/struts all around so I don't have to worry about a single pothole possible rattling my new BMW to pieces, popping the tires, or slamming my nuts on the seat. Either way, thanks for all the info!

I'm getting a CV axle and differential seal from Autozone tomorrow. Then I'll get that Behr FSR off eBay recommended by All2kool.



Literally, the owner's manual says to use either 5W-30 or 5W-40 dependant on the temperature range in my region. New England doesn't get so extreme to warrant a need for 5W-40. In terms of what kind of oil to use, I looked at the bottle and it says it "meets or exceeds the requirements of API SN/SM" which I remember reading somewhere is what E46's like. I did not find a single oil bottle saying anything with "LL01" on the front/back anywhere (Autozone, Advance Auto, Walmart, etc). I'd probably have to order that online or go directly to BMW (who is actually right down the road from me, coincidentally lol).

Motor oil becomes like religion in certain BMW circles because of rod and/or main bearing problems in the early S54s and the S85s. I live in SoCal and run Mobil1 15W40 in all my cars, including an M5 and an M3, and have never had an oil-related problem. My E30 has over 510,000 miles on it, and its original engine went 409,000 before I rebuilt it.

So pick a good synthetic, match its weight to your climate, and don't worry about it.

[legobumb]

Motor oil becomes like religion in certain BMW circles because of rod and/or main bearing problems in the early S54s and the S85s. I live in SoCal and run Mobil1 15W40 in all my cars, including an M5 and an M3, and have never had an oil-related problem. My E30 has over 510,000 miles on it, and its original engine went 409,000 before I rebuilt it.

So pick a good synthetic, match its weight to your climate, and don't worry about it.

That's exactly what I did, pretty much. Manual said to use either/or, and I chose one from the options that best suits my climate, and made sure it was synthetic. I grabbed high mileage simply because 200k+ miles lol.

EDIT
Unfortunately, ebay doesn't want to accept my debit card information for whatever reason, so I guess I'm stuck with going to carID for a FSR. Oh well. I knew there was a reason I stopped using ebay a while back.

[MarcoZandrini]

Yes, I am a bit “religious” about what oil goes in my engine. That Mobil 1 oil is too thin. Disregard that it never has met the BMW LL01 spec. The only M1 oil that used to meet the spec was the 0w40. Mobil changed its formula and not even that oil doesn’t meet the spec. You need to look harder for the “BMW LL01” logo on the label.

Did you flush the block when you installed the new pump? There’s a block drain under the exhaust manifold between cylinders 1 & 2. To change all of the coolant you need to remove this drain plug. You’ll need a new crush washer or else it’ll leak. Ask me how I know.

[legobumb]

Yes, I am a bit “religious” about what oil goes in my engine. That Mobil 1 oil is too thin. Disregard that it never has met the BMW LL01 spec. The only M1 oil that used to meet the spec was the 0w40. Mobil changed its formula and not even that oil doesn’t meet the spec. You need to look harder for the “BMW LL01” logo on the label.

Did you flush the block when you installed the new pump? There’s a block drain under the exhaust manifold between cylinders 1 & 2. To change all of the coolant you need to remove this drain plug. You’ll need a new crush washer or else it’ll leak. Ask me how I know.

No, I did not know about this drain plug. And no, I did not perform a coolant flush. I simply replaced what was already in there when I received the vehicle, which was Prestone 50/50. However, I have not had any leaks since doing the water pump and bleeding the system. I've even driven well over 1,000 miles since doing it. No leaks or overheating. The expansion tank is still full, so the system hasn't pulled any more from it since then, which I had kept a close eye on for a full week after doing the water pump in the first place. But this doesn't mean your information is useless! Now that I know about it, I will definitely keep that in mind. Thank you!

As far as "oil specs" go, I've done a bunch of reading around on this forum, e46fanatic's forum, and more - the general consensus is that BMW LL01 oil is preferred and actually allows you to go the full 15,000 miles before servicing again. BUT you can use an oil that meets/exceeds the API SN/SM specification as long as you change it well before the 15,000 miles (before it causes any damage from being broken down after that many miles). And I plan on servicing it again around the 7,500 mile marker anyways.

Thank you everyone who has replied to me on this thread! I will definitely be coming back with other questions in the near future. I can't wait to get this car in great condition as a daily driver who travels and average 500 miles a week (mostly highway).