high pitched squeal from under the dash
 

This started yesterday on the way to work. It is a low volumn high pitched whine that appears to vary in volumn depending on the RPM. Gut tells me it is a vacuum issue and something is acting like the reed on an oboe or something. Verified it is not the door alarm or key in the ignition or lights or anthing.

Anyone seen this before and what was the problem.

You may want to be a little more specific like what part of the dash? Is it the right side or left side?

I had a little squel coming from the right side on my 88 190e and what it was, was a air pump for the temp gauge of the cabin. Located on the right hand side of the dashboard, behind/beneath to the right of the glove box. Put a little trans fluid on the bearings and the squeal went away.

If it is a vacuum leak and it is serious that it makes lots of noise, do all the vents of the climate control function properly?

Iggy

Sounds like it is coming from the area of the instrument panel. I did notice a little warmer air coming out the center vent than normal as well. haven't tried it with AC on yet. Will do that on the way home and report back.

Did not hear the squeal coming home from work. AC blew cool until I got out on the main road and got up to speed then blew hot air. Is this maybe related. AC has not worked properly since I bought it 3 months ago.

Squeal is still there and the AC blows cold the first few minutes but after I get out on the road and get up to speed it blows warm air.

Any ideas what this could be. None of the search posts I looked at addressed this specific occurance.

i've heard the squeal a couple of times as well. try turning off the fan and if it goes away then it's the blower motor i'd assume.

happened to me once in my 190e2.6 as well.

i believe it was my speedometer cable. It was varying with vehicle speed, not rpm. It really freaked me out and I had to park the car to see what was wrong. Strangely, it went away and never happened again <knock on zebrano!>

Happens whether fan is on or not. This almost sounds like some audible warning of some sort.
Starts about 5 seconds after you start the car and will stop occasionally for a few seconds then start back up.
Anyone know of an audible warning sound that it might be?

If the ac is not working correctly, as you stated that when on highways it blows warm air, check out the actuators. It could be that one of the actuators, that controls outside/inside air mixutre (I think that this actuator exists) is not functioning properly.

As to the noise, are you sure it is not the interior temp pump that is making the noise? As I mentioned, I had the same noise, it would start a few seconds after start up and it was intermitant.

Iggy

Squeal from Under the Dash
 

I had this problem with my 2.6 liter engine and it was determined to be the belt tentioner. When you hear the squeal the belt is slipping and the rpm sensor in the back of the ac compressor gets out of sinc with the engine sensor and shuts off the ac compressor. That is why you are blowing cold until after the squeal then it blows warm. When that happens, pull over and shut off the engine and restart, it will resinc all sensors and your ac should blow cold again.

Try checking out the tentioner first, sound can play funny tricks on you while you are driving.

Let me know how it works out.

Sincerely,