Delayed blower motor in COLD weather? Needs 45min warmup to work.
 

I've posted this question over at mbworld with very little advice other than "change your CC unit" or "replace the blower motor regulator". This morning was in the teens, thus very very cold. So I warmed my 86' 300E up, the usual procedure is that the blower will not spin until the car is warm and I have to kill it and start it back up for the motor to start spinning. Tried this today and nothing http://www.mbworld.org/forums/images/smilies/eek.gif I would have toughed the cold out but the windshield was just icing up like crazy on the inside. I decided to let it warm up past the usual 15 min in hopes of success, 45min later I hop in and the motor is blowing....good to go! http://www.mbworld.org/forums/images...s/thumbsup.gif

Therefore I now believe this problem to be temperature dependent, from any of your guys experience/expertise what part in the blower circuit would be consistently faulty only during cold weather and progressively get worst in even colder weather? I hope this is not annoying you guys, I just have a BIG pet peeve about throwing parts at an issue without having a pretty solid idea of what is actually wrong because with my luck its never the "winning" part and my wallet ends up not talking to me for the next couple of days http://www.mbworld.org/forums/images/smilies/tongue.gif. I have also used the search function but nothing is close enough to adequately match my symptoms.

Thanks ahead of time guys!

This is just a quick thought, but I believe there is a coolant temperature sensor that tells the control unit to start the blower when the coolant has reached a pre-set temperature, so the occupants won't get blasted with cold air. A faulty sensor might not close the connection even though the coolant is warmed up. IIRC, this is within a couple of minutes even on a really cold day.

If your blower runs on high speed with the climate control wheel set to the maximum detent, and the defrost button pushed in, I think that overrides this sensor, like an emergency situation to blow air regardless of the control unit's settings. I thought that this was also a good test of the blower motor itself too.

Have you checked the fuses? Before I changed all the old corroded ones, my blower would 'trip out' if I used it on anything other than i or ii settings (Euro).
Even if they look OK with a quick look, they can be corroded where the spring clips hold the fuse in place.

I'll swap all the fuses related to the climate circuits today and post back with results. I have the blower set on the high fan speed thus it should override the AUTO climate control, it should spin regardless of outside ambient temp correct? Thanks for the help and suggestions so far folks :2thumbsup

Be aware that there are 2 fuses ..one feeds the Control Panel and the other is a heavier fuse for the bkower itself. Some chassis have the blower fuse outside the fuse box in an aux fuse holder. .....
There was that mod on your chassis , so it may have been done.
A trick is to put the fan ON defrost, key ON , and then spin the fuses in their holders...if the fan starts as you spin that fuse , you have a problem where the fuse sits in the holder ..Very common w/Benz fuses..they look good, but the holder connection is poor.

I may also mention that this delay appeared after I replaced the old motor with a new Bosch replacement. The old motor was severely sloppy as the bearing assemblies were completely worn causing a horrid racket. I suppose the worn bearings could have caused excess load, slowly raising the amount of current needed to operate the motor thus adversely harming the current bearing components? I shall check the fuses in the morning. Suppose a bit of fine sandpaper to the fuse holder contacts might not be a bad idea for a 23 year old car :P which brings to mind.......Happy New Years!

Sandpaper on the contacts is almost always a bad idea. You want a smooth clean surface, not a scratched one.

I agree........
You want to clean and polish them...and then replace the fuse.
The problem is dis-simular material of holder and fuse , plus oxidation b/c of the open style fuses Benz uses.. You do not see a bad fuse, and you can not see the poor/bad connection.

I just replaced them all, cost me $3. I bought a whole scad of them off Ebay, paid like $10 for a set of three 20 packs, in each color.....

As you replace, give a tiny squirt of Caig DeOxit on the contacts.


-tp

Good advice, I'll skip the 400 grit. I'll spray some electrical contact cleaner when I put new fuses in. I'll keep you all posted :2thumbsup

I've bought a set of copper-conductor fuses before, don't know if they are still offered but it seemed to help.

IIRC the climate control system has a general lockout until the coolant temperature reaches 40 deg C. Either your coolant thermostat is bad which does not permit the coolant to reach 40 deg C. within 40m minutes (doubtful) or the climate control sensor is bad which doesn't recognize that the coolant has reached 40 deg C. Mark

Mark,
I also thought the same thing. However, I feel as if this issue is somewhat intermittent at this point. Today once warmed up I killed the engine then turned it back on, after this any high current load switched on would actually activate the blower? Turning my blinkers on, headlights, or even the rear defroster seems to activate the blower..... its very strange :confused:. I need to run a few arronds then the new fuses will find their homes.

Note: I have tested all of the sensors dependent on temperature according to the service manual. I did this from the inside of the car after mapping out the corresponding pins on the connector that plugs into the CC unit. All seemed to be adequately within +/- tolerance.

New fuses did not help the problem unfortunately. I should also add that I can remember when I had the old battery in (badly in need of a deep charge) With the headlights on and heater (blower on full) the headlights would dim down and blower slowed only when the car was sitting at idle in traffic. This would diassapear when I accelerated. I suspect the voltage regulator to be the culprit for this issue but could it be related in any way?

My 190e 2.6 on statup blower worked for appr 2min cut off and if i drove car 10min blower fan started working again. This occurred repeatedly. I was advised to disconnect aux waterpump guess what blower motor ran flawlessly.
Earlier this week picked up a aux waterpump from salvage yard this one on startup will blow for 30sec and shutoff after 5min blows again. Again disconnected aux waterpump and blower works flawlessly. Try disconnecting aux waterpump.
My next step to replace electrical connectors which are corroded if that don't work then buy a new aux waterpump.

Great! I'll give that a try in the morning on a cold startup.

Never got the chance unplug the Aux.water pump. Today was the first time my W124 has failed me mechanically on a long distance trip (CT to Tuxedo Park, NY). Seems as if I'm experiencing the swollen brakeline symptoms. Early in the trip the car started to make a very strange noise, almost as if one of the wheels was not balanced correctly, a sort of harmonic low sound. I pulled over and kicked the wheels....maybe Firestone didn't tighten the lugs, not it......I then felt that the front passenger wheel was very warm. Emptied a bottle of poland spring on it only to watch it dissapear as steam :eek:. Thankfully I was near my girlfriends house so I limped it there and swapped cars, took her fathers Buick. After the trip I limped my car home slowly, half way home the blower cut out........and it cut out for good! Ahh whats that the old timers say? When it rains it pours?:rolleyes: I just ordered new brake lines for all four corners and splurged for a new blower motor regulator, keep your fingers crossed for me!

Went out today to put the new regulator in as there is quite a snow storm on its way. Unfortunately the regulator did nothing, I'm going to open the CC unit and look for anything out of the norm. If anyone has any suggestions for me at this point, consider them greatly appreciated. Also if any of you guys would be willing to help a fellow forum member out and have a spare CC Unit laying around for a good price PLEASE let me know. My car drives me nuts, but I'll never part with it :D!

I have a W116 79 300SD with exactly the same symptoms. As does another member who has been posting on the diesel discussion. If you get yours diagnosed please let us know. I have a plan to blow a heat gun on various components of the system in cold weather to see if I can figure out what is causing the problem. I switched out the amplifier and it made no difference. If temperature is above about 25 degrees or so, blower works flawlessly.
If I can't get mine diagnosed I may wire a separate circuit to the blower with a manual switch because I know it blows if I feed it 12 volts directly. It's not the coolant temperature cut out switch because that is bypassed in the defrost mode. I'm thinking it is a bad connection or cracked solder joint that is separating enough in cold weather to stop conducting.
The 116 has the earlier servo system but the problem also seems to occur in later 123 models without the servo since people with later 123's have reported the same problem.
It's a damn irritating problem.

I a having a similar problem on a 107 and it seems to be the blower motor/chassis connector - reseating it helps for a while. I'm going to look into cleaning it soon.

Lots of different system types mentioned in this post. On the later 123 system, a common blower problem is cause by corrosion at plug for the blower resistor block located on the passenger side fender well in front of the expansion tank. Frequently, the male and female pins need to be cleaned and the female pins need to be carefully squeezed tighter with pliers. Mark

blower speed amp fries
 

hi on my 1980 450sl i replaced the servo with a used working unit and a used climate control . first turned it on but only defroster blew air and the thmb wheel only stayed hot in ether positions. i replaced the amp speed control unit under the glove box . turned it on and the temp changed also the hi lo and by worked. the only thing the blower when in hi mode was not like in def mode
the system worked for 10 min then only defrost. , took out the amp box and opened it to see the transistor was toasted . what could cause this to happen,could the parts be that fiff, my old servo said 102 the replacement said 104 inside is the same
any help please also the door locks dont operate vaccume issue , the air dosent blow out center just top and bottom :D

A seized auxilliary water pump will take out the amplifier. Check your pump. You should fuse the auxilliary water pump with a low amperage fuse so that if it seizes and starts drawing excessive current, the fuse will blow before the amplifier burns up.
Search on auxilliary water pump fuse kit. There's a member here that has a nice little inexpensive fuse kit to solve the problem.

Here it is:
http://www.peachparts.com/shopforum/mercedes-benz-used-parts-sale-wanted/242553-1-amp-fuse-link-w123-auxiliary-water-pump-%96-plug-play.html?highlight=water+pump+fuse