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Manual vs. ACC Posted by Ari [Email]  (#2847) [Profile/Gallery]
(more from Ari) on Fri, 27 Jun 2003 05:43:47
In Reply to: blower motor and relay? Fan speed switch on high, Patrick, Thu, 26 Jun 2003 19:47:18 Members do not see ads below this line. - Help Keep This Site Online - Signup |
First, I doubt that the AC service is related. Anything is possible, but doubtful. Not enough to get a dealer to fix on his own dime. Now, if you found a wrench with the mechanic's name on it stuck in the blower motor, you might, just might, get the dealer to give you a complementary car wash the next time.
Cars with manual controls (knobs) use a resistor pack to control fan speed. Cars with ACC use a transistor. To replace the transistor, check out Quasi's page (http://www.quasimotors.net).
The resistor pack is on the left-hand side (looking forward) of the blower motor housing. With the hood open, remove the flat horizontal panel at the base of the windshield. It has an electrical connector, and plugs right into the side of the blower housing.
The resistor pack has three resistors - just coils of resistor wire, and a thermal fuse. If the resistor pack gets too hot, the fuse opens. The fuse is the one part that doesn't look like a coiled wire. You can buy a new resistor pack for about $80. The good news is that a new fuse is about $1. The bad news is that nobody I've ever found carries them - they have to be mailordered. The other bad news is that soldering in a thermal fuse without it opening is very hard.
Of course, it is possible to just jumper out the fuse and go on your merry way. There will be no overtemp protection.
One reason why thermal fuses may fail is due to running the fan on the lowest speed. In order to run the fan slow, you're throwing power away in the resistor, instead of the fan. The resistors sit in the airflow of the fan - the fan is there to cool the resistors. At the slowest speed, the airflow is least, and the power dissipated in the resistor is greatest.
Nobody's fan ever quits while driving - only when the restart the car. It's my guess that the resistor gets nice and hot running at the lowest speed because it's the highest power dissipation and least airflow. Then the car is stopped - no airflow, and all that heat still in the resistor pack. The temperature right at the resistor spikes, and the fuse opens.
posted by 192.249....
, Fri, 27 Jun 2003 05:43:47 <-- Viewing This Message
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