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no blower solution

878 Views 8 Replies 3 Participants Last post by  the APEMAN
I have an 89 brougham with no ac blower function. I have determined that I need a power module, not uncommon with age. A new one is $150. A used one is risky. I can make the blower work at high speed by shorting the tan power wire to ground. Can I attach a switch with variable speed and activate the motor from inside the cabin? Will this harm the ecc or other components?
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You can substitute a heavy duty relay to run the blower. Remember that this thing hauls down a lot of current so large wire is a must. Replacment of the power module should also include a check of current draw from your blower motor. In other words an old blower motor could draw higher current and ruin the replacement blower module. No, I don't have any numbers.
like The Ape man said about the old blower motor. If it is old and worn it does't help with WD40 or similar, in a little while the blowermotor goes heavier again, and uses a lot of current, that must pass the power module, and therefore can kill your new module.

My advice is to change the blowermotor to a new one when you change powermodule.

If I ground the tan wire to the blower, the blower works fine, but of course at a single maximum speed. The purpose of the modlue is to provide variable speeds depending on temperature needs. If I am happy with low, medium and high, and can find a switch, what is the harm? Unless powering the motor this way can send retrograde current that damages other computer components. Since the module is already bad, it isn't an issue. Regarding the blower motor amps, when I power it like i said, neither it or the wiring I rigged up overheats, so I don't believe it is drawing excess amps to have burned the first module. I believe the module just failed from age(18yrs).
What do you think?
No way can you tell blower current draw without an actual measurement. Your alternator will thank you if it gets fixed properly. Rigging up a switch will work but you need a switch and wiring heavy enough to handle the draw continuously, not just a few minutes. #14 wire and a 10 amp switch will not cut it. This is why a relay is preferred. These blower modules always went bad even when the cars were 3 years old. Probably better off taking a chance on a used one. Another concern is the inductive kick when shutting off the blower. The blower motor presents an inductive load to the car's electrical system. When the load is suddenly switched off it will kick back a high voltage spike right into the 12 volt system. Exact same thing happens with the AC compressor clutch which is why it has a backwards diode installed onto the connector. Voltage spikes are not good for your
ECM, voltage regulator and radio. Automotive electricity can be confusing.
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Thanks,Ape man. That's the info I was looking for in the first place. I am convinced now that a switch risks damaging the ecc or ecm electronics, a good reason not to do it.
I have a VOM that measures up to 10 amps DC. Can you guess at the proper amp draw for a blower motor?

Yes, the powermodule can go bad from other things that exessive current draw to the blower motor.
But, last autum the powermodule broke on my fathers brougham -87 and we did exacly what you did and added a switch, a double relay rated at 40 amps and a fuse to atleast get blower on full speed.
We also serviced the blowermotor with WD40 because it felt to go a little heavy.
That only worked a couple days because the blowermotor started go heavy again, and caused the 25 amp fuses to blow.

We lubed the blower motor again and it worked again.

The car was then not used during the winter and this spring when the car was put to use again the fuse blow again, we lubed the blower motor again and it worked again, it worked a couple of days and then blow the fuse. We also tryed with fuses up to 30 amp but they blowed after a cuople of seconds.

We then orded a new power module and blower motor but havent got it yet, we are in Sweden so the parts take a little while to get here and they cost total about 583$ before we have them.

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It sounds like your switch worked, but the fuse blows due to a bad blower motor. If you just replaced the blower, I bet the switch would have worked.
If the blower motor blows 30 amp fuses then it's bad. I think they draw in the teens or close to 20 after starting up.
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