Interior blower faulty - resistor? motor?

[chriscochris]

Recently the interior fans in my 2000 corolla starting to do weird things before dying altogether. At one stage only 1 or 2 speeds worked (which, from reading other threads wouold suggest blower motor resistor) but then the speed of the fan would fluctuate dramatically when the fan was on - almost like it had an infinite amount of speeds between off and full. Now it is dead and nothing happens. I have checked the fuse and replaced the relays with others out of a second hand corolla. Could it still be the resistor that is the problem? The air cond and heat level still works and you can feel the air coming through the vents at highway speeds but it is not fan-forced.

Any help or tips would be great! Thanks.

[Zembonez]

I'd bet on a blower motor resistor based on your description.

[NutsNBolts]

Sounds like the blower resistor as its speed related

[chriscochris]

Latest update..

I bought myself a multimeter as i really want to solve this without an auto-eleccy doing the work. The blower motor is definately fine - i shorted it across 12 volts and it works really well. I have tested to see whether there is power going to the plug that connects directly to the blower motor. There is power there but i think there is a bad earth. When i plug the negative of the multimeter into the negative pin on the plug i get no voltage BUT when i put the negative on the car chassis and put the positive of the multi to the positive pin on the plug, i get good voltage!!

So, how would i go about solving a bad earth issue? There is a cluster of wiring down there and it is all tightly packed together so i think to pull that apart would be hell.

Is is too dodgy to cut into the negative wire and run a new earth to a bare bit of the chassis?? Im open to suggestions!!

Thanks

[sam333]

Originally Posted by chriscochris

Latest update..

I bought myself a multimeter as i really want to solve this without an auto-eleccy doing the work. The blower motor is definately fine - i shorted it across 12 volts and it works really well. I have tested to see whether there is power going to the plug that connects directly to the blower motor. There is power there but i think there is a bad earth. When i plug the negative of the multimeter into the negative pin on the plug i get no voltage BUT when i put the negative on the car chassis and put the positive of the multi to the positive pin on the plug, i get good voltage!!

So, how would i go about solving a bad earth issue? There is a cluster of wiring down there and it is all tightly packed together so i think to pull that apart would be hell.

Is is too dodgy to cut into the negative wire and run a new earth to a bare bit of the chassis?? Im open to suggestions!!

Thanks

I dont think its bad to run a new ground. I have seen it, and done it many times.

[fishexpo101]

Could be a broken wire somewhere, be tough to find in that mess/tangle of wires. Running a new chassis ground is not a bad thing, pretty common with aftermarket car audio/video apps. The key is not introducing any ground loops that will cause interference with the rest of the electrical equipment in the car.

I'd try and find the chassis ground point for that wiring if possible, if not, then just run a wire to ground and test the operation. See if it is noisy or not (check for voltage between that need ground and another ground. Check it against the negative battery terminal as well - as long as you don't measure any voltage between the various ground - you are good to go.

[chriscochris]

FIXED!!

I replaced the plug that goes into the blower as i think the wire was kinked and not getting a good connection (there is not much slack in the wire and changes angle pretty sharply). That fixed the bad ground.

As i shorted the motor out and it worked, i assumed all was fine. BUT.... It only worked when held upside down!! Strange. So when i went to screw it back up into place it would cut out again. Other than a bad connection inside the motor i had no idea what this could be. The wreckers wanted $50 for one that looked like it was dredged from a swamp. i decided to pull mine apart and give it a bit of water dispersant and some compressed air to blow any dirt / junk out of it. Whatever i did worked and now it goes great!

Thanks for all your help!