I am hearing a heartbeat sound
 

When I get in my 85 300D and turn the key to the glow plug position, while I am waiting for the yellow glow plug light to go out, I hear a heartbeat sound coming from behind the dash. It happens if I have left the climate control on in the vent position (second button from the right). I think it also happens if I have left the A/C button on, but I usually turn off the A/C when I shut down the car. If I turn off the climate control by pressing the right-most button the heartbeat sound stops. I do not remember ever hearing this before. Has anyone else experienced this or have any clues as to what is causing it?

It could be a vacuum leak. The switchbank cluster in the center console is known to wear out.

I used to know a guy with this problem, it drove him crazy. Creepy dude too. His wife was like, 14 or so.

:) Thank you, Moon, for this insightful information. I will take it under advisement as I further my diagnosis. My wife was not a child bride but I do think of her has young and attractive (younger than me and better looking) so I have my doubts that this is a conttributing factor. And I cetainly hope that the sound does not drive me crazy. Or that I turn creepy over time. If my wife tells me that I am going over the edge because of this heatbeat sound, I will sell the car before I go nuts. (With full disclosure to the buyer, of course.) I hope it does not come to this.

I will add that the noise was not present today, so maybe it is intermittent. The humidity was noticeably lower today. Don't know if this is a contributing factor. Aside from the noise, everything else seems to be working just fine.

Sorry, IDK if you caught the Poe/Telltale heart reference or not. I think vacuum also, it might be the vacuum pods going to the defined position when you put the key to glow. You might look at what happens to the different vacuum circuits when you glow.

IIRC the volvo 240 climate controls were vacuum controlled also, they'd make some funny noises and thunks too.

[QUOTE=moon161;3732690]Sorry, IDK if you caught the Poe/Telltale heart reference or not. . . .[QUOTE]

HA! It escaped me. But I read this thread to my daughter and she got it right away. But now you have me thinking I should check the trunk. I first noticed the heartbeat sound after a friend borrowed my car. It was about midnight when he tapped on my door. Woke me up from a nap. Stormy night I remember. The next day his girlfriend, Lenore, was reported missing. Hasn't been seen since. I have resolved to not lend him my car again. Nevermore.

Uh, is this for real?

This might help:

www.goodreads.com/quotes/48648-once-upon-a-midnight-dreary-while-i-pondered-weak-and

https://en.wikipedia.org/wiki/The_Tell-Tale_Heart

A bit off topic but interesting none the less.

Maybe I should go back to putting on my seatbelt after I turn the key for the glowplugs. That way the alarrm for the seatbelt will drown out the heartbeat. Especially if I have a passenger.

When you said heartbeat sound it rang true to my car also, the rythem I hear every morning starts off slow then gathers a quicker beat ,at the very end it says ,get out ,GET OUT ,like that?

Um... I think your car has problems...

Eddie Murphy said it best...

"GET OUT

"Too bad we can't stay!"

Knowing almost nothing about this issue...
 

I'll ask if it's possible that the vacuum is not indeed the issue. I'd suggest before you turn the switch on you might open the vacuum system and allow the vac to bleed down.

Or does it sound more like Arnold? https://www.youtube.com/watch?v=DCSwRM1qiXU
If it sounds like Schwarzennegger, that is a bigger problem indeed and I would heed the warning.

Sounds like a good idea to elminate a variable. For now the problem has stopped on its own and I do not know why. If it starts up again with regularity, I may try that. I am thinking that I could repeatedly turn on the key to see if the sound is reliably emitted. If it is I could then pull a hose, drain the vacuum, and see if that eliminates the sound.

Congratulations! Is it a girl or a boy?

Kidding aside, when you said heartbeat sound I think of the heart valves opening and closing that make the rub-dup sounds. To me that sounds like you need to inspect the check valves in the dashboard especially if it's related to the AC (dash pods?).

I did not have the A/C button depressed, only the vent button. But aside from that, how would I go about inspecting the check valves? By pulling a vacuum line and using my MightyVac? Can I get to the pods without taking the dash out?