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I'm not a mechanic, but I have time and no money, so I'd like to fix this myself if I can.
The blower motor stopped working over the course of weeks. It began by not turning on immediately on starting the vehicle, but would come on after a few moments. As time passed (three weeks) the fan would take longer and longer to fire up after starting the vehicle. Once the fan came on on any particular trip it would stay on (and I could turn it on an off successfully) for that trip. For the past two weeks it has not worked at all.
So far I have:
Checked the 50 A blower motor fuse - which looked perfect - and cleaned it.
Replaced the 50 A blower motor relay.
Checked for power at the relay - I do have power there in the 50A side, and do have power to the coil side as well. The coil side power does switch on and off with the HVAC control switch on the dash.
I have no power coming to the fan motor speed control switch on the dash. As I've said the HVAC control switch is sending power to the coil side of the relay, and seems to be correctly controlling the dampers and the AC compressor.
I tried to remove the Fuse and Relay block under the hood to get to the back side and look for loose connections but didn't succeed in getting it out.
If you have power to the relay coil (86) and common (30) and no power out of the relay (87) with a new relay then you have a bad ground at ground G100.
G100 is located on the left front of engine compartment, at LH upper radiator support.
Well, while we were checking for G100 we noticed that the blower motor resistor in the back of the blower motor housing was looking bad - turns out it had corroded and burned out quite badly. I've just finished putting that back together - a new thermal limiter and a new plug as well.
This did not cure the problem, so now I'll go and look for G100 again.
You may wonder why we were looking by the battery for G100, when you clearly said it was in the left front. All I can say is, "Oh, you meant THAT left front..."
I looked for any accessible grounds under the hood and attempted to tighten them all. I did find one by the battery that I was able to tighten up a bit, though it was not wiggly loose by any means.
I then checked for power at the fan motor plug and have power there. Whether or not I had it there before I don't know. In any case, the fan turns now - but very slowly and loudly.
So, it seems to me that the fan motor is toast. Is is possible that the motor, when going out, burned up the Blower Motor Thermal Resistor? In other words, did the motor, as it was going out, cause the rest of the trouble, or are the two problems merely coincidental?
My plan for tomorrow is to get a blower motor installed.
By the way, the relay sounds like it is functioning - audible clicks in response to turning the HVAC control on the dash "on" and off.
If the relay clicks then G100 is OK.
By the way the left side is the drivers side.
High speed bypasses all the resisters so if it turns slow at high speed setting then I would say you have a bad fan motor.
The thermal limiter and the plug that goes into it were both corroded and cooked, so I replaced them.
I found one ground that was able to be tightened, but I'd hardly call it loose.
The fan motor was making funny noises - when it finally came on after replacing the limiter and plug - so I replaced it. The first new motor ran for about 20 minutes then died. So far the free replacement is doing well. And now that I've replaced the thermal limiter I have four fan speeds again, rather than the one I've had for the last three years.
Thanks, SubFord, for your very quick responses, and thanks to the FTE creators and maintainers - you helped this rookie get the job done.
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