Now what ?

Originally Posted by ahull

If you mean the relay/control module (silver/gray) box on fan unit, my understanding is they are not sold separately from the whole fan itself.

I know you can buy the relay that fits into a coolant hose and turns on the fan. Are you talking about something else?

Yes there is a fan switch that can fail. Try changing that.

Originally Posted by vandyboy

I know you can buy the relay that fits into a coolant hose and turns on the fan. Are you talking about something else?

That's not really a relay per se.... more like a sensor. I suggested that a few weeks ago but OP is talking about the actual control box/relay on the fan assembly itself (look at the picture he posted at the link in post #23). Once that craps out, I think you have to buy a whole new fan assembly for it.

Originally Posted by ahull

If you mean the relay/control module (silver/gray) box on fan unit, my understanding is they are not sold separately from the whole fan itself.

Originally Posted by ahull

That's not really a relay per se.... more like a sensor. I suggested that a few weeks ago but OP is talking about the actual control box/relay on the fan assembly itself (look at the picture he posted at the link in post #23). Once that craps out, I think you have to buy a whole new fan assembly for it.

yes this is what i'm talking about

Originally Posted by vandyboy

I know you can buy the relay that fits into a coolant hose and turns on the fan. Are you talking about something else?

after doing some research, i realized that there is the coolant level sensor, that sits below the expansion tank, and temperature sensor that fits inside the coolant hose. the coolant level sensor has nothing to do with turning the fan ON/OFF since its only purpose is to simply check how much coolant u have.
now, what's the difference between the temperature sensor and that relay that sits on the fan i'm referring to? which one tells the fan to go ON/OFF?
if the sensor or relay are dead, shouldn't they give a code when reading from OBDII? (cuz i'm not getting anything )
if not, i'd rather spend 20$ as a precaution and check whether if the sensor is faulty prior to spending 250$ on the entire fan unit.
awaiting ur feedback and help cuz i'm tired of spending money around based on guesses, since i already got a thermostat and water pump and still facing issues

if you read my post that quotes the inputs to run the fan, you'll see what tells it to turn on or off. the temp sensor in the hose does send a signal to your relay box on the fan to tell it to run when the coolant temp is too high. the relay box actually connects the power to make it run once it gets the signal from the various input sources. I'm not sure a failed sensor will throw a code in this case.

if your fan runs with the A/c on but not when the car gets hot, I'd suspect the temp sensor. From what posts I've seen, usually when the relay box fails, the fan either runs too slow/not at all or runs for hours after you shut the car off and kills the battery over and over. I also hate replacing parts unnecessarily, but it's less than $20 in this case (and easy enough to do yourself as is the fan) so I'd rather throw $20 first before I throw hundreds if I'm not entirely sure.

Originally Posted by ahull

if you read my post that quotes the inputs to run the fan, you'll see what tells it to turn on or off. the temp sensor in the hose does send a signal to your relay box on the fan to tell it to run when the coolant temp is too high. the relay box actually connects the power to make it run once it gets the signal from the various input sources. I'm not sure a failed sensor will throw a code in this case.

if your fan runs with the A/c on but not when the car gets hot, I'd suspect the temp sensor. From what posts I've seen, usually when the relay box fails, the fan either runs too slow/not at all or runs for hours after you shut the car off and kills the battery over and over. I also hate replacing parts unnecessarily, but it's less than $20 in this case (and easy enough to do yourself as is the fan) so I'd rather throw $20 first before I throw hundreds if I'm not entirely sure.

thanks for the info bro
well the radiator light came on yesterday, so gonna get it scanned tomorrow and hopefully it'll tell me exactly what's going on.
hopefully it'll be a matter of sensor that i can replace and get this thing over with...
on a side note, i realized something the other day. the fan does not turn on EVERYTIME i turn on the A/C, sometime it does sometimes it doesn't. i read some place that the fan turns on if it's necessary, depending on the ambient temperature, meaning if it's already cold and u turn on the A/C, the fan will not work...

so today i'll be taking my ZHP to the mechanic to get the codes scanned
seems she knows that
as i'm coming to work today on my 30min drive in the morning, the fan is running exactly when it's supposed to, no heat problem, everything's perfect
i should probably tell her "all we'r gonna do is plug in a cable in ur OBDII port and read some codes, it won't hurt don't worry"

got the car scanned, turned out to be a faulty temperature sensor. changed that, and got 1 day life out of it
next day, car's overheating again, and again i'm forced to turn the AC on to get the fan running to reduce the heat...
i noticed that it's drinking 1 liter of water daily. i cannot see any leakage from any of the coolant components. after today's drive to work, parked the car, opened the hood, no leak whatsoever and couldn't hear any hissing voice indicating a leak (engine was off of course, and it was a 30min drive).
the way i see it, 2 tests should be done, compression/leakdown test for a blown head gasket (hopefully not ) and cooling system pressure test for any unseen leak.
also, the cooling system was bled successfully, no bubbles whatsoever, no mayo on dipstick nor oil cap, no oil in the coolant, and the exhaust did not smell sweet (at least didn't smell sweet to me )
any thoughts? more like encouragements towards a leak instead of a blown head gasket?

Did the mechanic seal the O ring on the sensor properly? That is a source of leaks. Also, try and take off the plastic shield from underneath your car and see if there is any water accumulation there. God I hope I never have to face such mysterious gremlins on my car.

Sorry to hear about the cooling issues, I have been dealing with a similar problem that seemed to be the Coolant Temp Sensor O Ring. My new phrase is "You know you're a BMW owner when you ignore the gas gauge and focus on the temp gauge. I had to laugh when I read this line, coming from a member with over 500 posts. "changed the hose attached to the tank and the plastic thingy attached to the radiator near the tank since both were leaking". I hope that you can get the issue resolved easily.

Originally Posted by tcphoto

"You know you're a BMW owner when you ignore the roads and focus on the temp gauge."

that's more like what i'm goin through
so did the cooling system pressure test, got it steady on 19.5 psi and no leaking whatsoever.
went to my dad's mechanic (since closer to home), inspected it, told me to go to his friend who specializes in cars' electrical issues. we're there, kept it running to test whether the fan would run if the car heats up, it did heat up and the fan remained off. plugged in his scanner, sent a command for the fan to turn on, still off. to my luck, he had an X5 radiator fan sitting by and it fits my fan's plug perfectly as soon as he plugged it in and bam! the fan started running
so today gonna go and buy me that relay that sits on the fan which is faulty, and pray for the best
however one thing is bugging me (didn't do the compression/leakdown test, too scared to yet ) but i've been told that due to extreme pressure, since the car is overheating and the fan is off, the radiator cap kinda like expands and let some of the pressure out of the cooling system as not to let the cooling system explode, hence why i'm losing coolant at the moment. not sure how accurate this theory is
so to keep me in high spirit, my mechanic told me to fix the fan, and than IF i'm still experiencing coolant loss, to do a compression/leakdown test...
keeping my fingers crossed here

I believe you had two separate problems. You replaced the temp switch and got the fan working again. From what I can tell, the fan is still working, right? Unless the o-ring for the temp switch is messed up or missing, I would bet you have a leaking expansion tank or a bad water pump. I had to replace my expansion tank recently and was losing about the same amount of coolant every day just as you described. They are leaky little bastards after a few years.

Originally Posted by vandyboy

I believe you had two separate problems. You replaced the temp switch and got the fan working again. From what I can tell, the fan is still working, right? Unless the o-ring for the temp switch is messed up or missing, I would bet you have a leaking expansion tank or a bad water pump. I had to replace my expansion tank recently and was losing about the same amount of coolant every day just as you described. They are leaky little bastards after a few years.

actually he plugged in the entire BMW X5 fan into my car and it ran perfectly. he switched back to my fan, and it didn't turn on not even when he gave it the ON command from the scanner.
yesterday got the relay and gonna install it today, hopefully it'll all workout for the best...
as for the expansion tank leak, there isn't any leak whatsoever, pressure test came positive and held at 19.5 psi
i'll monitor it for the next couple of days and see what happens.
thanks guys

So he got the relay/control box only? I'd be interested to know where it can be sourced. Glad you got it worked out.

we have lots of shops that have car parts, just had to check at a few of them for wrecked fans and get the relay off. was lucky to find one

Originally Posted by heztheone

actually he plugged in the entire BMW X5 fan into my car and it ran perfectly. he switched back to my fan, and it didn't turn on not even when he gave it the ON command from the scanner.

It's often easier to find the problem, when you can borrow some parts for moment.

Originally Posted by lgr122

It's often easier to find the problem, when you can borrow some parts for moment.

so true
beats the hell out of the mechanic tellin' u "change this 200$ part, if it doesn't solve ur problem, we'll change the next more expensive part... we'll keep doing this until ur problem is solved"