1997 E420 Weak air circulating fan - PeachParts Mercedes-Benz Forum

Hal Crocker · #1 03-26-2009, 03:14 PM

1992 E420 AMG.AIR circulating fan has become very weak. The small fan in the console above windshield (I guess a temp sensing device)was noisy. It seemed to stop functioning about the same time the circulating fan became weak. Are the functions of these two fans inter-related? How can the problem be corrected?

Hal Crocker · #2 03-26-2009, 03:18 PM

The E420 is a 1997.

TMAllison · #3 03-26-2009, 04:35 PM

You have two sets of filters that could restrict airflow if they've not been changed in a while. There are cabin filters and charcoal activated filters.

Could also be the blower regulator is going bad whihc has been a common W210 malady. Yours must be repalced as a blower motor/regulator/squirrel cage fan "assembly". Its pretty pricey. Later models had separate replaceable components. The is a W140 regulator that some folks have spliced in as a replacement. Search will find the procedure if needed.

bobs · #4 03-27-2009, 04:58 AM

That small fan is called an aspirator blower. It samples ambient cabin air to tell the AC what the temperature inside the car is. You can verify if it is still working or not by placing a small square of tissue paper over the vent. If the fan is working properly it will cause the tissue to stick there.

It could very well be the reason your main blower has slowed down. If the AC system thinks the cabin is warm/cool enough it will slow down the main fan to where it is barely running.

A couple of easy tests:

1. Use the manual fan speed buttons and turn the blower on to maximum.

2. Set the temp controls to all the way hot or cold.

If the blower speeds up then the regulator/motor are probably OK.

If you failed the tissue test above, replace the aspirator fan and things should start working again.

If you can't remember the last time the pollen & recirculation filters were replaced then it's time to do them. They can have a big effect on the amount of air the AC system can move.

Hal Crocker · #5 03-28-2009, 09:35 PM

Thanks Terry and Bob. Looks like I have a regulator/motor problem.Can anyone help me find the procedure to replace theW210 system with the W140?

TMAllison · #6 03-28-2009, 09:51 PM

First do yourself a favor and start it with AC on HI, if blower does not come on reach up and give the fan squirrel cage a couple of good 1/2" nudges clockwise and see if it fires up. If so, the blower motor brushes are shot and it stopped on a dead spot. The motor is sealed but it may be possible to open it up and replace them.

Here is the W140 regulator retrofit. Does not fix a dead motor. http://forums.mbworld.org/forums/e-class-w210-sponsored-bekkers-imports/153918-early-w210-blower-motor-regulator-replacement-diy-here.html

Shballard7 · #7 10-15-2009, 10:20 AM

Call 888-333-4642 ask for Phil. I to thought I had this problem. but mine was the actual motor. the part I received from Phil, it came with 2 wiring harnesses one that looks the same as the splicing pictures From the link to the MB website, but the other was perfectly made for my the E class mid 90's Benz. my is a 96 e300d. I was impressed. Unfortunately I have a short in the blower motor.

paste the part # 1408218451 in the search box, look for the Bosch product. it does not show both wiring harnesses but I have attached some pictures of what comes in the box. Bosch has made it with a clip at the regulator so you can use either wiring harness.

Thanks phil