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  #1  
Old 06-15-2015, 03:22 PM
rrgrassi's Avatar
mmmmmm Diesel...
 
Join Date: Jun 2006
Location: Royse City Tx
Posts: 5,177
A/C Fuse keeps popping...'82 300D

Hey guys, it's been a while, due to health issues and carrer change...anyway, the blower motor was pulling too many amps. I replaced it with a URO from Pelican. System came up great, and no more fuse popping while the car was sitting and idling with the A/C on.

When I went to take the car on a test run, the fuse blew. Replaced the fuse, and set the blower on the low setting while driving. It was fine, until I used the middle or automatic setting. As the fan speed ramped up, it blew the fuse, again!

I am at my wits end trying to find the issue...

Any ideas?

Thanks!

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RRGrassi


70's Southern Pacific #5608 Fairmont A-4 MOW car

13 VW JSW 2.0 TDI 193K, Tuned with DPF and EGR Delete.

91 W124 300D Turbo replaced, Pressure W/G actuator installed. 210K

90 Dodge D250 5.9 Cummins/5 speed. 400K
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  #2  
Old 06-15-2015, 06:33 PM
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Join Date: Nov 2004
Location: North central Texas
Posts: 2,596
Make sure the fuse holder is very clean and use ceramic fuses. Once the contacts become a little oxidized and resistive they will melt the fuse. I've soldered a pigtail ATC fuse holder to the contacts before to get away from the problematic fuses.
Every blower I've seen draws a lot of current for the fuse they used.
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  #3  
Old 06-15-2015, 07:24 PM
rrgrassi's Avatar
mmmmmm Diesel...
 
Join Date: Jun 2006
Location: Royse City Tx
Posts: 5,177
Thanks Whiskey!!

How is Farmersville treating you?
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RRGrassi


70's Southern Pacific #5608 Fairmont A-4 MOW car

13 VW JSW 2.0 TDI 193K, Tuned with DPF and EGR Delete.

91 W124 300D Turbo replaced, Pressure W/G actuator installed. 210K

90 Dodge D250 5.9 Cummins/5 speed. 400K
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  #4  
Old 06-15-2015, 07:32 PM
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Location: North central Texas
Posts: 2,596
Rainy all day. Not complaining though as it's filling up the pool.
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  #5  
Old 06-15-2015, 08:16 PM
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Join Date: Jan 2003
Location: Gastonia, NC
Posts: 1,354
interesting...

I just replaced a brand new blower in my w124 300D. I replaced it with a used blower from a parts car. The new blower kept popping the AC fuse. After I removed it and installed a good used one it has yet to pop an AC fuse. The new blower pulled way too many amps. In fact, it blew a 25amp fuse in short order. The new/used blower is doing fine on a 16amp fuse. Go figure.
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  #6  
Old 06-15-2015, 09:12 PM
TnBob's Avatar
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Join Date: Dec 2009
Location: Shelbyville, Tn
Posts: 1,907
Id be connecting an amp meter to that blower motor and see what its actually drawing. I hope this isnt the beginning of another uro horror story
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1985 300D 198K sold
1982 300D 202K
1989 300E 125K
1992 940T

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  #7  
Old 06-15-2015, 09:28 PM
rrgrassi's Avatar
mmmmmm Diesel...
 
Join Date: Jun 2006
Location: Royse City Tx
Posts: 5,177
This started two years ago, but since life got in the way...I need to get a good amp meter. Mine on reads to 10 amps. It started blowing the fuse with the Bosch motor I bought in 2006. One of the last available I was told.

I hope it's not a Uro Horror story as well. They seem to more miss than hit.

I am thinking about putting the fan circuit on a relay, like I have on my 90 Dodge truck.
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RRGrassi


70's Southern Pacific #5608 Fairmont A-4 MOW car

13 VW JSW 2.0 TDI 193K, Tuned with DPF and EGR Delete.

91 W124 300D Turbo replaced, Pressure W/G actuator installed. 210K

90 Dodge D250 5.9 Cummins/5 speed. 400K
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  #8  
Old 06-15-2015, 11:40 PM
rrgrassi's Avatar
mmmmmm Diesel...
 
Join Date: Jun 2006
Location: Royse City Tx
Posts: 5,177
The fuse blew again, this time on low. I do not get why I can let the car idle for 20 minutes, with the system in automatic mode, but when I go down the road, the fuse blows. Must be a short somewhere. I tried the same thing, but with out the compressor engaged, fuse blew as well.
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RRGrassi


70's Southern Pacific #5608 Fairmont A-4 MOW car

13 VW JSW 2.0 TDI 193K, Tuned with DPF and EGR Delete.

91 W124 300D Turbo replaced, Pressure W/G actuator installed. 210K

90 Dodge D250 5.9 Cummins/5 speed. 400K
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  #9  
Old 06-16-2015, 02:20 AM
MBeige's Avatar
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Join Date: Apr 2005
Location: SoCal
Posts: 3,746
If you kept the old blower and the armature isn't too worn, you can replace the brushes after cleaning it thoroughly.

Years ago, the fuse on mine (16A) kept blowing when the AC was used. Cleaned the blower motor and replaced the brushes, all is well until today.
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  #10  
Old 06-16-2015, 01:24 PM
rrgrassi's Avatar
mmmmmm Diesel...
 
Join Date: Jun 2006
Location: Royse City Tx
Posts: 5,177
I do have the OEM motor still. I'll check that. I wish they made a coreless motor this size!! I did read somewhere that you can use a blower motor from a Ford F series that fits with some modifications.

BTW, your car still looks fantastic!
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RRGrassi


70's Southern Pacific #5608 Fairmont A-4 MOW car

13 VW JSW 2.0 TDI 193K, Tuned with DPF and EGR Delete.

91 W124 300D Turbo replaced, Pressure W/G actuator installed. 210K

90 Dodge D250 5.9 Cummins/5 speed. 400K
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  #11  
Old 06-16-2015, 02:33 PM
Diesel Preferred
 
Join Date: Oct 2007
Location: Charleston SC
Posts: 2,788
At idle, your alternator may be only providing 12 - 12.5 volts. Once you get the engine speed up, it may jump to 13.5 - 14 volts. Higher voltage - more power available - the motor draws more current - the fuse blows.
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Respectfully,
/s/
M. Dillon
'87 124.193 (300TD) "White Whale", ~392k miles, 3.5l IP fitted
'95 124.131 (E300) "Sapphire", 380k miles
'73 Balboa 20 "Sanctification"
Charleston SC
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  #12  
Old 06-16-2015, 03:05 PM
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Join Date: Aug 2010
Location: Sacramento, CA
Posts: 3,115
A common problem on all cars, at least thru the 1980's. We suffered without AC for 5 yrs in FL since my father ASSumed the glass fuse for the blower in our station wagon was OK because the wire was still there. He finally tried a new fuse and instant AC. The wire had melted right at the cap, due not to excessive current but from heat at the corroded contact (I did say FL). In other cars, I have had the blower speed switch melt. You are lucky that just your fuse popped. Most 82-85 300D's have melted plastic at the #8 fuse, giving a wobbly fuse holder.

Search for my post on adding a relay to power the "blower relay box" in my 1985 300D directly from the battery, thus bypassing the fuse-box and other boxes. I gave pinouts and photos. I need to do similar on my 1984, which surprisingly doesn't have a melted #8 fuse yet. I also found the culprit for the excessive resistance in the fuse-holder, though most here don't believe me. I believe my ohmmeter. I similarly added a relay in all my 1960's cars (for "blower high" switch position).
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  #13  
Old 06-16-2015, 06:26 PM
rrgrassi's Avatar
mmmmmm Diesel...
 
Join Date: Jun 2006
Location: Royse City Tx
Posts: 5,177
Thanks, Bill! I am using a blade fuse and holder since the #8 in the OEM holder melted through years ago...
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RRGrassi


70's Southern Pacific #5608 Fairmont A-4 MOW car

13 VW JSW 2.0 TDI 193K, Tuned with DPF and EGR Delete.

91 W124 300D Turbo replaced, Pressure W/G actuator installed. 210K

90 Dodge D250 5.9 Cummins/5 speed. 400K
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  #14  
Old 06-16-2015, 07:31 PM
DeliveryValve's Avatar
Chairman of my Benz
 
Join Date: Jun 2006
Location: Central California
Posts: 4,159
Quote:
Originally Posted by rrgrassi View Post
Thanks, Bill! I am using a blade fuse and holder since the #8 in the OEM holder melted through years ago...
Glad to see you back! If you are using a blade fuse, what amperage are you using?
I make a fuse link that plugs in directly to the blower. I know a 16 amp blade fuse is not readily available and a 15 amp will always blow on the fuse link. So your only readily available choice is a 20 amp fuse.
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  #15  
Old 06-20-2015, 10:58 PM
rrgrassi's Avatar
mmmmmm Diesel...
 
Join Date: Jun 2006
Location: Royse City Tx
Posts: 5,177
I separated the fan from the rest of the system using a 4 amp relay. I am using a 25 amp fuse. It's great to be back.

Oh, I also changed from Freeze-12 to Duracool. That stuff feels like R-12 with the cooling, and less head pressures on the compressor.

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RRGrassi


70's Southern Pacific #5608 Fairmont A-4 MOW car

13 VW JSW 2.0 TDI 193K, Tuned with DPF and EGR Delete.

91 W124 300D Turbo replaced, Pressure W/G actuator installed. 210K

90 Dodge D250 5.9 Cummins/5 speed. 400K
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