I've got coolant on the passenger's side carpet and assume the core needs to be replaced. Question: It's too cold to tackle it now so can I just turn the heater knobs off to keep coolant from leaking any more? Car's a '95 855 with 175K miles.

Thanks for your comments!

Dukester

Yes, do check carefully that it's actually coolant.
But I'll bet it is. Quite common on 850s and easy to fix.
I'm going to try to tackle ours during "winter break".
In most cases it's easy, but I'm going to change the heater hoses too.
--
"Differences of opinions should be tolerated, but not if they're too different' - Sharon Craig

May not be heater core. Drain under fresh air filter sometimes clogs causing water to fill the firewall cavity and find its way to the passenger side carpet. Easy to check this before investing time and money in replacing what might be a good heater core.

No. Coolant flows through the core whenever the engine is turning over.

Replacing the core is not 'tough', and look on Ebay for a 'cheap' new core for around $50.

Leave the covers off both sides of the center stack and place shop towels or paper towels next to the leaking core to absorb the coolant. Getting coolant out of the carpet is a pain and if the coolant gets to the underside of the rubber mat and into the foam, almost impossible to dry out or clean up.

http://www.ebay.com/itm/Volvo-Heater-Core-850-S70-V70-C70-1994-through-2000-lifetime-warranty-/360771828487?pt=Motors_Car_Truck_Parts_Accessories&fits=Make%3AVolvo%7CModel%3A850&hash=item53ffad3b07&vxp=mtr#ht_8675wt_944