(Home) Fan speeds up when I brake

Hi All,

Got abit of a funny one,my fornt inside fan will only blow at half speed even when on full speed,at first i check the resistor and also removed the speed control switch and took it part and clean all the copper contacts,i am 99% sure that resistor and speed control switch are not the problem,the ace is going in on 10th may to have air con allover and i would like to try get fan going first,i have notice with speed set on full the fan runs very slow and every time i brake the fan blows full speed but as soon as car slows and i take foot off brake the speed drops back to slow speed
i am trying to picture what has the brakes to do with fan speed,once ace slows or stops or i pull away the fan slows , it only go into full speed when i brake ?

any one out there had this before

dennis

- (#10410) dennis, 25 Apr 04 13:29

I'd check for a loose fusible link or bad earth... You really need a voltmeter or testlight connected to the fan switch to see whether it is getting 12v the whole time. If not, trace back...

- (#10410) David Miller, 25 Apr 04 13:47

Many thanks Dave.

I have found the fan unit behind the glove box and I took the 3 screws out that hold the fan unit in the housing and gave the fan a shake (as I could not see how the fan housing comes out)after i gave it a good shake put screws back in and fan worked fine for 4/5 days,to me this indicated that the problem is local to the fan unit,how do you take the fan out and could it be the motor ? the fan is now back to how it was before the big shake.

dennis

- (#10410) dennis, 30 Apr 04 10:06

Short or sticky brushes?
I think getting the fan out will indeed mean removing the housing too. The air inlet bolts to the body above the headlamp (outside), but I'm unsure as to whether it'll come out from behind the dash reinforcement. Might be a dash-out job...

Voltage and current checks are in order. You need to find out whether it's getting a full 12v going to the motor when the fault is present. If so, brushes. If not, resistor, switch and wiring.

- (#10410) David Miller, 30 Apr 04 10:56

Cheer Dave,

I was hoping you would say dash out job,i have not checked to see if i got 12v across fan motor , i will get my voltmeter and check i take it that fan will need to be set on full speed to have 12v on lower speeds the voltage will be choked by the resistor ?
i will test on full speed,where is the best place on the wiring to test as i can not see how to get to fan terminals with the big cross beam in the way

dennis

- (#10410) dennis, 1 May 04 02:35

Dennis,
Very odd fault! If you park up and run the engine in neutral, does the fan speed up when you apply the foot brake?
If it does, then remove the stop/ tail bulbs one at a time then repeat the test. The chance is that there is corrosion within one of the bulbs where the earth connection to the bulb body is. This can cause a new path for grounding through the lighting circuit when the stop lights are on. I once sorted a car that had been in a main dealers workshop because if the brake pedal was pressed when switching off the engine it kept running until the footbrake was released! The main dealers couldn't sort it. Replacing the bulbs was all that was needed. There may be brake lights in the tailgate as well as the corner clusters)
If the above test is negative, ignore this theory!!
Good luck ... Ray
- (#10410) Ray Ambler, 1 May 04 04:00

Ray

The fan will not speed up if parked up only if she moving and the braking has a effect of everything trying to move forward,you know if you say doing 30mph and you brake then you feel your body being pulled forward ,once you stop or take your foot off brake you seat back in your seat,every time i brake the fan speeds up to full speed and as soon as i stop or take my foot off the brake the fan slows down or sometimes stops,my problem is how do you remove the fan housing or can you just remove fan from its housing without taking out housing or pulling the dash apart

dennis

- (#10410) dennis, 1 May 04 07:25

Dennis,
You can reach the fan cage if you remove the nearside headlamp. I will send you a detailed photo showing fan cage. There isn't an air intake filter so leaves & just about anything can find its way into the chamber. You can reach in to remove debris. (I removed a part page from a jap newspaper!) You can also lube the bearings with WD40 or spray grease. Ray

- (#10410) Ray, 1 May 04 07:58

Thanks Ray,

Got the download,and now i have read your posting i now understand it a picture of the outside rather has i was thinking the inside,i will take the nearside headlight out tomorrow and take a look,i should able to feel to see if bearings are bad or any debris,i was thinking about spraying electrical contact cleaner into the fan motor to see if i could clean it.

seems funny not to have a filter in front of the air inlet hole , i wonder if it would be any good to fit abit of wire mess over the opening ?

i will keep you posted

dennis

- (#10410) dennis, 1 May 04 13:31