1997 Mercedes Benz 280 intermittent whistling noise when CL

Hello -

On one of the TSB, Heater Blower is Noisy; it states the air intake below the windshield is obstructed by leaves etc.

There is another one, Knocking/Humming Noise at idle with A/C on. . ...I have attached the info on it.

I would also check the cabin air filter and replace it. I have attached that for you as well.

If you haven't every changed this. . ...you would be surprise how much debris can be in there.

I would look at the air intake area and clean that out really good. Then remove the blower and clean all of that area out and then the filter and see if that makes a difference. If not then check into the other TSB.

Cabin Air filter

]

2 Cover
3 Clip

1 Dust filter

Removal and Installation :

Remove cover panel below instrument panel. See: Body and Frame Interior Moulding / Trim Dashboard / Instrument Panel Service and Repair
Take off cover (2). Push the two remaining clips (3) in the direction of arrow for this purpose.
Pull dust filter (1) down and out (arrows).
Install in reverse order.

Knocking/Humming Noise at Idle With A/C On

All Technical Service Bulletins

Hello -

I think this is what you are asking for. I have attached vacuum routing for the climate control. What you may be talking about is near item 35. . ..I think this is where it comes through the firewall. I would start at 36 and work my way into the car.

35 Cockpit separation point
36 Vacuum valve block
38 Vacuum element for defroster outlet flaps
39 Vacuum element for footwell flaps
41 Vacuum element for center nozzle diverter flap
44 Vacuum element for fresh/recirculated air flap
45 Vacuum element for left center nozzle blend flap
46 Vacuum element for right center nozzle blend flap
Y11/3 Switchover valve block (8 connections)

Color Code :

bl = blue
hbl = light blue
drt = dark red
ge = yellow
mgn = medium green
gr = gray
rt = red
ws = white
sw = black
dgn = dark green

Hey also, it looks like you may have some recalls on your vehicle. The dealer may fix these for free. Please contact the dealer service department, give them the VIN number of your car and have them check on these to see if they apply to you. I would check these out also.....

1999080001
12/01/1999
Recall - Infant Restraint/Booster Seat Exchange

NHTSA99E024000
08/02/1996
Recall 99E024000: Child Restraint & Booster Seat Defect