W126 Owners - Keep a Fire Extinguisher In Your Car!! - Page 3 - PeachParts Mercedes-Benz Forum

daw_two · #31 05-02-2013, 12:22 PM

Quote:
Originally Posted by Whiskeydan

Never use the blower on low speed if your W126 is composting leaves. I believe it's in the FSM somewhere.

Quote:
Originally Posted by daw_two

Hey Whiskeydan --- I'm guessing you mean the AUX fan out front. So, how do we make it run on HIGH all the time? Bridge connect the temperature sensor on the front of the engine?

Quote:

Originally Posted by vstech

no. he's talking about the cabin blower. the leaves under the brake booster on the early 126 cars crowd around the resistor pack for the cabin blower, the lower the speed it's turning, the hotter the resistor pack gets. run the car on high speed fan only, and the resistor gets zero heat.
so either do not run the blower, or only run it in high mode.

You are not going to believe this

---- I have thought for YEARS that the resistor pack down there was for the AUX Fan low speed.

So, someone explain to me the low speed/high speed on the AUX fan --- or do I have that all mixed up, too.

compu_85 · #32 05-02-2013, 12:30 PM

On the Gen1 cars there are 2 resistor units under the brake booster... the one for the cabin blower regulation and the aux fan low speed. On the Gen2 cars it's just the aux fan low speed, but they also have larger aux fans so imagine that resistor gets hotter than the Gen1 cars.

The AC pressure or temp switch kicks the aux fan onto low. High coolant temp kicks it onto high speed (generally 110*C).

-J

eatont9999 · #33 05-02-2013, 12:33 PM

Quote:

Originally Posted by daw_two

Quote:
Originally Posted by Whiskeydan

Never use the blower on low speed if your W126 is composting leaves. I believe it's in the FSM somewhere.

Quote:
Originally Posted by daw_two

Hey Whiskeydan --- I'm guessing you mean the AUX fan out front. So, how do we make it run on HIGH all the time? Bridge connect the temperature sensor on the front of the engine?

You are not going to believe this

---- I have thought for YEARS that the resistor pack down there was for the AUX Fan low speed.

So, someone explain to me the low speed/high speed on the AUX fan --- or do I have that all mixed up, too.

I can't speak for other models or years but my gen 1 W126 has never ran the Aux fan at any other speed than max. It is either on or off. I believe the relay is inside the fuse box.

I always keep my CCU on Auto, so the resistor would be hot in most cases. I plan to keep that area clean and be aware of the potential danger. I will also stay prepared for another leaf event.

compu_85 · #34 05-02-2013, 01:06 PM

I'll have to review the diagrams to be sure.... perhaps they "upgraded" the aux fan at some point before the Gen2 switchover... 84 perhaps?

-J

vstech · #35 05-03-2013, 10:28 AM

Quote:

Originally Posted by compu_85

On the Gen1 cars there are 2 resistor units under the brake booster... the one for the cabin blower regulation and the aux fan low speed. On the Gen2 cars it's just the aux fan low speed, but they also have larger aux fans so imagine that resistor gets hotter than the Gen1 cars.

The AC pressure or temp switch kicks the aux fan onto low. High coolant temp kicks it onto high speed (generally 110*C).

-J

Hmmm... I do not think there is any aux fan circuitry under the booster. I think everything is for the blower.

Jaybob should be able to find out by tracing the wiring plans he's got.

compu_85 · #36 05-03-2013, 10:56 AM

Quote:

Originally Posted by vstech

Hmmm... I do not think there is any aux fan circuitry under the booster. I think everything is for the blower.

The area between the firewalls can be a real no-man's-land... hard to see down there.

On GenII cars the blower control lives inside the HVAC box. It's attached to the bottom cover with the blower motor.

-J

vstech · #37 05-03-2013, 11:09 AM

Quote:

Originally Posted by compu_85

The area between the firewalls can be a real no-man's-land... hard to see down there.

On GenII cars the blower control lives inside the HVAC box. It's attached to the bottom cover with the blower motor.

-J

is that pic from a Gen I or a Gen II?
I'm sure the 603 powered 126's have aux fan resistors, I'm not sure the 617 powered ones do.

pmckechnie · #38 05-03-2013, 11:20 AM

I just checked my Gen 1 84 500 SEL and found:
Under the break booster is 2 resistor parts
1. Pre-resistor for the Aux fan low speed
2. Blower resistor assembly for blower speed control.

I will be cleaning mine out often. In fact, I think I will look into using some kind of screen wire cover. I'll let you know what I come up withl.

I don't have one but I am sure that the Gen 2 126 has a solid state controller under the dash and doesn't have a resistor under the hood. Not sure about the pre-resistor for the aux fan. My 124 has one behind the left headlight.

Paul

daw_two · #39 05-03-2013, 11:54 AM

Quote:

Originally Posted by vstech

is that pic from a Gen I or a Gen II?
I'm sure the 603 powered 126's have aux fan resistors, I'm not sure the 617 powered ones do.

Naturally, I'm talking about 300 (and 350) SDLs....so I'm in the Gen II, w126 park.

vstech · #40 05-03-2013, 12:03 PM

well live and learn... great, only thing to do is shut off the system if burning is smelled.

whunter · #41 05-03-2013, 12:10 PM

Quote:

Originally Posted by eatont9999

For all W126 owners. You NEED a fire extinguisher in your car. A $20 investment could save your vehicle!

I experienced the need and use of my fire extinguisher today on my way home from work with the AC on. I pulled into a store parking lot while on my errands run and I noticed that there was a smell of burning leaves getting stronger. I thought at first someone was burning something outside so I opened the car door to see if in fact it was coming from outside. It was not. I smelt the air coming from the vents and it smelled like the burning leaves I had smelt before. As soon as I looked up, I saw smoke pouring out from under the cowl of the hood. I exclaimed a few choice words as I hurried to pop the hood, shut everything off in the car and get the fire extinguisher out of the trunk. I was initially thinking it was a fire in the fuse box or associated wiring but after looking under the brake booster, I saw the embers and smoke. I quickly dispatched the embers and thanked my lucky stars that it was not something more serious that I could not get to. I also thanked myself for buying and keeping a fire extinguisher in the car for this exact reason.

I vacuumed out all the leaves from this area not three months ago. Don't think that just because you cleaned them out, there won't be a problem! Luckily I was prepared.

I have been warning W126 owners about this for many years.
Warning: all W126 owners.

blower fuse started a fire in my engine compartment!

.

cirrusman · #42 05-03-2013, 03:59 PM

Even if it's a good idea to carry a fire extinguisher in your vehicle, whatever it might be, the leaf fire could have been extinguished with plain water, if there was no extinguisher handy...

Whiskeydan · #43 05-04-2013, 10:01 PM

Anyone that has a pre '86 W126 aux fan running two speeds has a problem. It's either on or off.

eatont9999 · #44 05-05-2013, 01:49 AM

I had no idea there was so much confusion about the blower resistor on the W126! Hopefully this thread will resolve some unanswered questions.

First thing you should do with any electrical related fire should be to shut off any systems that you can while you park the car and investigate.

HuskyMan · #45 05-05-2013, 05:18 PM

I have a 2.5 pound Halogen fire extinguisher I keep in the 560, but have nothing for the 300DT. Question: Would a C02 fire extinguisher stop a runaway diesel engine? If yes, would it be a better choice for the diesel than a halogen fire extinguisher?

Thank you for any help!