Cooling Fan issue related to HVAC delete?

ortho281 · 03-09-2016, 11:01 AM

Has anyone else had the issue with the cooling fan staying on all the time regardless of engine temperature, following complete HVAC removal including heater core and AC modules?

Jolette also has the same issue following HVAC removal and I wanted to see if anyone else has heard of this or had a similar issue? He had BMW master tech run tests on his car and checked the whole system. They could not find anything wrong, not even a fault in the DME.

Any info on this issue is greatly appreciated!

bigjae1976 · 03-09-2016, 08:33 PM

If its like most other fans...there's a relay somewhere that probably has an open circuit. The fan is probably wired to shut off when the relay coil is activated. When you deleted the AC and HVAC modules, you may have removed a ground that would keep the coil energized and the fan off.

I think you should either wire the fan to a manual or temp controlled switch. I used a DPDT switch in my E46. I have 3 positions: 1) off 2) on w/ ignition on 3) on w/ignition off. Should be pretty straight forward...switch, SPDT, relay, and some wires.

ortho281 · 03-10-2016, 08:04 AM

Quote:

Originally Posted by bigjae1976

If its like most other fans...there's a relay somewhere that probably has an open circuit. The fan is probably wired to shut off when the relay coil is activated. When you deleted the AC and HVAC modules, you may have removed a ground that would keep the coil energized and the fan off.

I think you should either wire the fan to a manual or temp controlled switch. I used a DPDT switch in my E46. I have 3 positions: 1) off 2) on w/ ignition on 3) on w/ignition off. Should be pretty straight forward...switch, SPDT, relay, and some wires.

Thanks James! The manual switch is one of the options we have been considering. I would however prefer a temp controlled switch to eliminate forgetting to switch the fan on/off.

bigjae1976 · 03-10-2016, 08:10 AM

The pain is locating a spot to weld in a bung for the sensor. If you have an all aluminum radiator then it should be easy.

If you have an OE radiator, you can try splicing in a fitting into you lower radiator hose which would be a spot for the temp sensor.

ortho281 · 03-14-2016, 01:52 PM

Quote:

Originally Posted by bigjae1976

The pain is locating a spot to weld in a bung for the sensor. If you have an all aluminum radiator then it should be easy.

If you have an OE radiator, you can try splicing in a fitting into you lower radiator hose which would be a spot for the temp sensor.

Yeah, the 2nd option would be much easier. Thanks James!

doogee · 03-14-2016, 02:52 PM

Quote:

Originally Posted by ortho281

Yeah, the 2nd option would be much easier. Thanks James!

Being a track car, I'd just run a manual switch for the fan.

The second you unplug the Climate Control, the fan behaves this way.

ortho281 · 03-15-2016, 07:34 AM

Quote:

Originally Posted by doogee

Being a track car, I'd just run a manual switch for the fan.

The second you unplug the Climate Control, the fan behaves this way.

Thanks! That would be a simple fix!

bigjae1976 · 03-15-2016, 08:37 AM

I would either run a temp switch or leave the fan always on. Just takes one time to forget to turn the block and heads into a $25k paperweight.

ortho281 · 03-15-2016, 03:15 PM

Quote:

Originally Posted by bigjae1976

I would either run a temp switch or leave the fan always on. Just takes one time to forget to turn the block and heads into a $25k paperweight.

With my luck that would be me! I definitely prefer doing a temp switch for that reason.

jolette · 03-15-2016, 08:49 PM

Figured I'd update, I had some time today to work on my car and have determined that the removal of the AC module was the cause of the constantly running fan. I chose to plug the module back in and secure it, out of the way behind the dash. Everything operates normally again.

///Mobbin · 03-15-2016, 10:29 PM

Nice, good info. I'm curious if you had to do any coding in connection with removing the HVAC system to avoid error messages?

jolette · 03-16-2016, 05:28 PM

Quote:

Originally Posted by ///Mobbin

Nice, good info. I'm curious if you had to do any coding in connection with removing the HVAC system to avoid error messages?

I actually didn't get any error lights at all, the only issue was the continuously running cooling fan. Didn't even throw any codes on the factory BMW scan tools.

ortho281 · 03-17-2016, 03:15 PM

Quote:

Originally Posted by jolette

Figured I'd update, I had some time today to work on my car and have determined that the removal of the AC module was the cause of the constantly running fan. I chose to plug the module back in and secure it, out of the way behind the dash. Everything operates normally again.

Thanks for sharing this! I will be trying this also.

magus4286 · 11-30-2020, 04:17 PM

I know this is a REALLY old thread, but ...

Paging ortho281 or jolette, I'm in the process of stripping down my car for a racecar build and just hit the point where I'm ready to get the HVAC out. What did you guys do for the heater core delete/bypass in your cars?

I don't see an off-the-shelf heater delete kit like for the E36/46, so trying to identify which of the few possibilities I can see has worked out well in practice. I can see a few options, including (1) just looping together the supply/return hoses that go to the heater (i.e. replacing the heater core with a hose), or (2) removing the heater core supply hose between the auxiliary pump and heater and connecting it to the return line to the expansion tank to which the heater return currently connects, (and I'm assuming removing the entire aux. pump and all of those lines is not the best idea).

Thanks!

Thanks!

maicol76 · 12-03-2020, 10:02 AM

1) Connect the pressure sensor installed around the A/C compressor to the original connector.
2) Connect the A/C control panel to the original connector.

These two are essential to make the radiator fan to work normally.

jl052699 · 10-21-2021, 03:53 AM

Hello, everybody I'm new to this platform, i have a 09 e92 m3 my current problem is that my cooling fan is always on while driving you hear hear it a lot at a stop light I don't if it is a bad water pump, temp sensor or relay, the temperature also always creeps over the 210 mark a moves up and down spontaneously, the car doesn't over heat coolant levels and everything thing are good so I don't know where to start and i live in the midwest so temperatures outside right now are not that hot for the fan to turn on, if anybody has had this issue or has any opinions on what it could be if you can reply it would be appreciated. Thanks

03-09-2016, 11:01 AM	#1
ortho281 Major 203 Rep 1,164 Posts Drives: 2011 E92 M3 6MT Join Date: Aug 2010 Location: Katy, TX iTrader: (1)	Cooling Fan issue related to HVAC delete? Has anyone else had the issue with the cooling fan staying on all the time regardless of engine temperature, following complete HVAC removal including heater core and AC modules? Jolette also has the same issue following HVAC removal and I wanted to see if anyone else has heard of this or had a similar issue? He had BMW master tech run tests on his car and checked the whole system. They could not find anything wrong, not even a fault in the DME. Any info on this issue is greatly appreciated! __________________ Akra GT4 / MS Stage 2 / MS UDP / BPM Tune / KW CS / H&R Sways / TMS Delrin / ST 380/355 BBK / Cantrell 2.5" Ducts / SR34 Pads / Apex Arc-8 / Hoosier R7's / Mode GT4 Splitter / GT4 Canards / APR GT-250 Wing / Cantrell Half Cage / Recaro Pro Racer / Schroth Profi II-6 / BMW Alcantera Wheel / Cool Shirt / ESS Fire Supp / Solo DL
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03-09-2016, 08:33 PM	#2
bigjae1976 Major General 1570 Rep 8,075 Posts Drives: 11 E90 M3 Individual Join Date: Mar 2006 Location: Houston, TX iTrader: (22) Garage List 2004 BMW M3 [4.50] 2011 BMW E90 M3 [5.25] 2013 BMW 328i [5.00]	If its like most other fans...there's a relay somewhere that probably has an open circuit. The fan is probably wired to shut off when the relay coil is activated. When you deleted the AC and HVAC modules, you may have removed a ground that would keep the coil energized and the fan off. I think you should either wire the fan to a manual or temp controlled switch. I used a DPDT switch in my E46. I have 3 positions: 1) off 2) on w/ ignition on 3) on w/ignition off. Should be pretty straight forward...switch, SPDT, relay, and some wires. __________________ 2018 F30 320iX Melbourne Red 2011 E90 M3 Monte Carlo Blue 2004 E46 M3 Imola Red 2000 E36/7 Z3 Steel Blue
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03-10-2016, 08:10 AM	#4
bigjae1976 Major General 1570 Rep 8,075 Posts Drives: 11 E90 M3 Individual Join Date: Mar 2006 Location: Houston, TX iTrader: (22) Garage List 2004 BMW M3 [4.50] 2011 BMW E90 M3 [5.25] 2013 BMW 328i [5.00]	The pain is locating a spot to weld in a bung for the sensor. If you have an all aluminum radiator then it should be easy. If you have an OE radiator, you can try splicing in a fitting into you lower radiator hose which would be a spot for the temp sensor. __________________ 2018 F30 320iX Melbourne Red 2011 E90 M3 Monte Carlo Blue 2004 E46 M3 Imola Red 2000 E36/7 Z3 Steel Blue
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03-15-2016, 08:37 AM	#8
bigjae1976 Major General 1570 Rep 8,075 Posts Drives: 11 E90 M3 Individual Join Date: Mar 2006 Location: Houston, TX iTrader: (22) Garage List 2004 BMW M3 [4.50] 2011 BMW E90 M3 [5.25] 2013 BMW 328i [5.00]	I would either run a temp switch or leave the fan always on. Just takes one time to forget to turn the block and heads into a $25k paperweight. __________________ 2018 F30 320iX Melbourne Red 2011 E90 M3 Monte Carlo Blue 2004 E46 M3 Imola Red 2000 E36/7 Z3 Steel Blue
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03-15-2016, 08:49 PM	#10
jolette Hammer_Down!! 58 Rep 663 Posts Drives: e92 M3 6MT Join Date: Jul 2012 Location: Upstate, NY iTrader: (16)	Figured I'd update, I had some time today to work on my car and have determined that the removal of the AC module was the cause of the constantly running fan. I chose to plug the module back in and secure it, out of the way behind the dash. Everything operates normally again.
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03-15-2016, 10:29 PM	#11
///Mobbin Colonel 1478 Rep 2,672 Posts Drives: m3 Join Date: Jul 2011 Location: Houston iTrader: (3)	Nice, good info. I'm curious if you had to do any coding in connection with removing the HVAC system to avoid error messages? __________________ 2021 Alfa Romeo Stelvio Quadrifoglio \| 2.9L \| Trofeo White Tri-Coat \| 8-spd
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11-30-2020, 04:17 PM	#14
magus4286 Private 18 Rep 85 Posts Drives: '08 E90 M3 6MT Join Date: Jan 2013 Location: Wayland, MA iTrader: (0) Garage List 2016 F15 X5 50i M-S ... [0.00] 2014 F15 X5 35d xDrive [0.00] 2008 E90 M3 [0.00]	I know this is a REALLY old thread, but ... Paging ortho281 or jolette, I'm in the process of stripping down my car for a racecar build and just hit the point where I'm ready to get the HVAC out. What did you guys do for the heater core delete/bypass in your cars? I don't see an off-the-shelf heater delete kit like for the E36/46, so trying to identify which of the few possibilities I can see has worked out well in practice. I can see a few options, including (1) just looping together the supply/return hoses that go to the heater (i.e. replacing the heater core with a hose), or (2) removing the heater core supply hose between the auxiliary pump and heater and connecting it to the return line to the expansion tank to which the heater return currently connects, (and I'm assuming removing the entire aux. pump and all of those lines is not the best idea). Thanks! Thanks! __________________ E90 ///M3 ('08) Racecar build \| Fire Orange \| 6MT \| MCS 3W w/ rear coilover \| Alcon BBK \| Akrapovic Ti + BW Racing X-Pipe \| do88 cooling \| All the aero \| Solid almost everything \| CF Roof \| TA16 and SM-10 wheels \| AiM PDM32
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12-03-2020, 10:02 AM	#15
maicol76 First Lieutenant 194 Rep 305 Posts Drives: E92 M3 Join Date: Oct 2011 Location: CA, Santa fe iTrader: (0)	1) Connect the pressure sensor installed around the A/C compressor to the original connector. 2) Connect the A/C control panel to the original connector. These two are essential to make the radiator fan to work normally. __________________ 2011 LCI W/DCT / K&N drop in filter / CSF radiator / do88 oil cooler / do88 DCT cooler / Akra Evo / Moton CS 2 way coilover / Wiechers strut bar(F) / ARC strut bar(R) / Alcon Superkit BBK / Tarox rotor / Geoff steel EHPS / Sard carbon-Kevlar GT wing / GT4 carnard / Aim Evo4+G-dash+GT Steering+S/C GP HD / Bride Zeta3 / etc.
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10-21-2021, 03:53 AM	#16
jl052699 Registered 0 Rep 2 Posts Drives: 2009 e92 M3 Join Date: Oct 2021 Location: Des Moines, IA iTrader: (0)	Constantly running fan Hello, everybody I'm new to this platform, i have a 09 e92 m3 my current problem is that my cooling fan is always on while driving you hear hear it a lot at a stop light I don't if it is a bad water pump, temp sensor or relay, the temperature also always creeps over the 210 mark a moves up and down spontaneously, the car doesn't over heat coolant levels and everything thing are good so I don't know where to start and i live in the midwest so temperatures outside right now are not that hot for the fan to turn on, if anybody has had this issue or has any opinions on what it could be if you can reply it would be appreciated. Thanks
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