Car is an 89 245 DL with AC

I'm not sure if the hissing has been there and I just took notice of it today or it just popped up today. Here's the scoop. Upon start-up or when I turn the key to the ON position (which lights up all the idiot lights), I hear a hissing sound coming from the dash. It kind of sounds like air coming out of something. I think it comes on again when I shut off the engine (I don't remember; it might not though). The car runs fine and nothing weird is going on in the dash. I'm just curious what this hissing sound is and if it's a normal occurence. Thanks guys!

Aha! Hissing sound with key in on position but engine not running (and hasn't run for more than 30 minutes) can only be the electric fan motor. Vacuum will probably bleed out with ignition off for 30 minutes or more.

Unfortunately, any part in the heater/AC unit is no fun to fix: much physical contortion required. Maybe you are younger and more flexible than I.

It may challenge your patience and flexibility, but technically it is pretty easy to fix. Plan to spend an afternoon and you'll probably finish early. I used plumber's putty to seal the replacement fan to the air box: easier to find and much less expensive than that sticky black stuff Volvo used. Easier to clean up after, too. Don't use much -- roll it to the thickness of a worm and put a single bead of it in a circle where the fan mounts to the air box sheet metal.
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-- Bruce / '82 244 (298k miles!), '86 745, '87 760Ti, '94 854

Sounds like when you modified your vacuum line you DID pull it off the inside nipple
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'75 Jeep CJ5 345Hp ChevyPwr and two motorcycles: it wasn't Volvos safety , it was Longevity that sold me

Yo ugly,

Have similar prob on '81 244, the A/C has been bypassed on this beast. Doubtful prob is there.

Methinks it's a vacuum leak, my lousy back keeps me from crawling under dere.

But your post reminds me that in addition to all those lines and vac motors, (one at each duct/outlet?) there's a vacuum tank, Swedish looking thing, clearish plastic, can't miss it on '81-83s I know it'd be immediately right of accelerator pedal. A long cylindrical thing, w/some bubble-like protuberances. Haynes manual shows it in blow up of HVAC stuff. Tank is there as a vacuum "sump" (?)for smooth operation of all those flaps.

Am going to boneyard tomorrow for various bits, sounds like a useful spare part, thanks for memory jolt. Coffee not enuff anymore.

Undoubtedly a Volvo (240?)-specific part.

Anyone out there know?

Regards,

Frank in OH

Ducky: Yeah, it might be the fan, but my belief is one of two other places to look...you have a small vacuum leak in one of the vacuum "motors" that power the flaps that direct air to the dash vents, floor vents, or defrosters, or a slight crack in the hoses that feed these motors. You'll have to pull the underdash panels and possibly the glove box to look and listen. The second possibility is that your AC is a bit low on gas and the sound you hear is the unit getting up to pressure, especially if you leave the AC on all the time....you didn't say if the noise occurred when the AC or defroster was activated. If the sound is truly a "hiss" as you describe, then these are the places to look. Happy hunting.


Brad

It's probably from your blower fan. It's either got something stuck in it or it's on it's way out, bearing are starting to go.
Pull the fuse for the fan and see if it quits.
The fan runs all the time at it's lowest speed even when set to the lowest position on the switch. Another better idea from Ford... I mean Volvo.
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Rob Bareiss, New London CT ::: 86 244DL, 87 244DL, 88 744GLE: 625K total