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240 240 HVAC fan stopped

57plymouth

Active member
Joined
Jul 23, 2015
Location
Blythewood, SC
1991 245 with no major modifications.

Last night the fan for the air conditioning inside the cabin started changing speeds. I had it set at 3, but the fan would speed up and slow down. Today it does not work at all.

I checked the 3rd fuse and it appears good. I will test it when I get home.

I am thinking blower resistor. Could it be the switch? If it is the resistor, where should I get a good one? Should I replace the motor at the same time? Can I do this with the dash in the car?
 
The blower motor is a big ass job I've done two and pretty much plan on a three day weekend to do it.Take lots of pictures your about to tear the dash down to the firewall.Plan on keeping the car? Then do the heater core while your that far in. I would also see if anyone near you has a spare blower fan in case you break them trying to take them off,yes there's two, or it's allready cracked from rust,heat,age. Now I put a vdo in mine and a four seasons in the other and thank god both are still working, however the vdo I put my truck burned up after a year
 
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Yes it's most likely that the resistor pack has gone bad. you have to remove the blower motor in order to effectively remove the existing resistor pack. You might as well change the blower motor at the same time. It's probably on its way out anyway.I've done several of these now and it's far easier to change the blower motor by removing the dash rather than trying to work under the dash with it installed. Heater cores up to you if you change it. And yes it really is a weekend-long job to get it done.
 
If you replace the blower motor then make sure the flange is in the correct spot (it it is manufactured correctly). I installed one where the flange was slightly off compared to the original. I compared the motors before installing, but they were close enough that I didn't notice. It was a lot faster the second time (4 hours?).

In case you want to check the resistor before taking things apart, I just went out to the garage and measured the resistor I took out of the car. The resistor has four wires, Black / Brown / Whiteish Brown / Blue
I used black as a reference (ie GND), and measured the resistances relative to this point.
Brown to black: 1.5 Ohms
Whiteish brown to black: 2.5 Ohms
Blue to black: 3 Ohms

These values do not include lead resistance so will probably be slightly higher if you measure them at the connector.
 
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See here, and test any new setup prior to install. I've done them in a day but it's still a major pain in the a$$. Replace anything else that looks sketchy under there as well, you don't want to have to do the same job twice. Also what's the consensus on the newer blower motors these days everyone? I've heard VDO went down the toilet.

Oh yeah, lube the wiper assembly while you're at it.
 
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For the record, I have replaced the dash in this car already. I installed a crack free dash a few years back. I'm really not scared of taking this apart, I just don't want to set aside a whole day to do it again.

Who sells a reputable fan blower motor and resistor? Should I replace the heater core? Is a 1991 a model with a door for the heater core or should I look up the chainsaw method. My air conditioning works too good to mess with it right now.
 
A good quick test to see if it is the resistor is to put your fan setting on 4. If the fan is running on high speed and runs good. Only the resistor is bad. High speed setting bypasses the resistor. That being said. To go in there for the resistor you may as well replace the fan motor, too.

Volvo still supplies the plastic fan wheels for a somewhat reasonable price. They still supply the resistor and blower motor too. Ching$$. I've used the four seasons one and the siemens/vdo one. They both did the job and only required a bit of adapting to fit up. In my experience the aftermarket resistors can be ok but the terminals on the wires are crap. So be careful when using the aftermarket part.

My suggestions on things to avoid. Do not mount the resistor anywhere else. Do not use anything but a stock original type heater core if you do get into that replacement. The center airflow through the heater core cools the resistor. Even when the heat is on.
 
The fan does not spin on any speeds. Am I wrong that I should swap that resistor anyway since I will be in there?

Any more thoughts on parts suppliers? Should I try IPD for everything? Or what?
 
Oh well, if you know the fuse is good. Then the fan motor is probably gone. I use FCPEuro, EEuroparts, and Rock auto for this stuff nowadays. FCP is nice with the warranty which they have always handled returns well for me.
 
pop the dash out like you have done before. flat rate on the job is 6.5 hrs ,that is on the field wound motor up grade..
 
Thank you gentlemen. A quick survey says the volvo motor is $430, and the volvo resistor is $73. Are the VDO fan and MTC resistor known to be good? Those are IPD prices. I'll look b at Eeuro, Rock Auto and FCP. I've never had good luck with rock auto shipping prices though.
 
You can test the resistor as suggested. Many times it is just the motor has failed. But the resistors fail as well. Test with a meter like described earlier.
 
don't know about the MTC resistor, but I've used the VDO blower motor on two projects now and the work well.

On all aftermarket blower motors, the motor doesn't have the little feed tube for the wires. Not an issue, just use some zip ties and carefully route the wires.

You will likely break the blower wheel when removing it (unless you are very lucky). The first time I did this, I had to pause to wait on new wheels to arrive. The second time I just ordered them up front. New blower wheel clips are a nice to have as well.

Its also a good possibility that the main blower feed wire/fitting is heat damaged. I replaced the spade on both occasions.
 
You will likely break the blower wheel when removing it (unless you are very lucky). The first time I did this, I had to pause to wait on new wheels to arrive. The second time I just ordered them up front. New blower wheel clips are a nice to have as well.

Note: the fans are different. A left and a right.
 
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