Windshield Fogging

TrishP · Post by **TrishP** » 03 Jan 2019, 20:06

Greetings~
Current situation with my '98 S70 is ---my windshield is fogging---or so I thought....
Rather, it seems to be an oily residue accumulating on the inside.
When I clean it with Windex it stays clean a short time.
I have read of some possible scenarios, but just wondering if anyone here has had similar experience?

Post by **RickHaleParker** » 03 Jan 2019, 20:18

Sounds like a leak in your heater core. If it is a heater core leak, the oily residue is vaporized antifreeze that has returned to a liquid or sold state.

TrishP · Post by **TrishP** » 03 Jan 2019, 20:29

Hi Rick:
Thank you.
That was one of the scenarios I've read, but a wet floor was mentioned along with it.
Also, would my antifreeze level drop?
I think this started last Spring, if my memory serves me well.
Is a new heater core an expensive fix?

Post by **cn90** » 03 Jan 2019, 20:32

Heater Core is an easy job.
Tons of DIYs in forum.

Dealer HC is about $110-$120 or so.

Search forum for ebay HC from Estonia, it is about $40 or so on ebay. This is as good as Volvo dealer HC.

Post by **RickHaleParker** » 03 Jan 2019, 21:19

It does not take much to fog the Windshield. A tiny leak, too small to wet the floor will do. The leak could be so small it would take a long time to see a drop in the reservoir.

Genuine Volvo OEM heater core ~$175.00. You can get Nissens which is OEM for ~$75.00.

Post by **scot850** » 03 Jan 2019, 21:21

It doesn't take much coolant to cause the issue. You may not notice the leak as the carpet often hides the damp which is under the carpet and it is rubber backed. Often you find the damp in the rear RH foot well first before you notice it in the drivers side.

It may not be a big leak, but may be slight weep from the 'o' ring seals into the heater core. At the age of the vehicle and assuming it is the original you are on borrowed time so worth checking. If you carefully peel back the carpet on the drivers' side foot well from the center tunnel area you can sometime see a line of coolant has left a run in dust below the carpet.

Another thing to check is that the drains in the windshield wiper motor cubby are clear. If they block or the 2 forward of that that are in the front of the plastic wiper motor cover, it can cause water to back up and drain into the heater system. That in turn can cause the A/C evaporator to rot out and it may allow the A/C oil to get into the cooling system which could also cause the oily film you are getting. Does your A/C run ok?

Neil.

Post by **E Showell** » 04 Jan 2019, 02:46

If you go the eBay cheapo core route (as I have done before) make sure you run it through the dishwasher before installing. Otherwise you'll be smelling an oil residue from manufacturing for months.

Post by **erikv11** » 04 Jan 2019, 10:18

Yes heater core and water drain lines are suspects but note carefully what Neil said: Leaky o-rings are a common cause of this, especially when it first shows up in the winter. Metal pipes shrink in the cold, and old o-rings leak.

Pull the carpet up and look at where the heater pipes go into the firewall, just above the accelerator pedal. Then you can inspect the surface of the under-carpet covering, for a trail of white residue where the pipe is leaking from the firewall coupler. If you also remove the plastic side panel, next to the driver's right shin, you can also look for the telltale residue from under the heater core.

The car shipped from the factory with Behr heater core, not Nissens. Most people go with the eBay cheapo core.

TrishP · Post by **TrishP** » 04 Jan 2019, 12:32

I appreciate all the input!
What Neil mentioned about the drain hoses resonates with me as I did notice a huge pool of water in the back left area under the hood a few months ago after a heavy rain. Our driveway has a lot of trees and am frequently cleaning the debris. The drain was clogged with compost ;( I did not know there were several drains, as Neil mentioned. The AC did work this summer. IF the situation is due to the drains/AC evaporator issue--how is that remedied? Will check for stains under the carpet....
Now, if the heater core is the culprit.....don't know if my husband would be willing to tackle that! I watched several videos and it reminded me of the dishwasher repair we recently did. Let's just say patience is a virtue

Post by **E Showell** » 04 Jan 2019, 15:58

Not an incredibly difficult repair. 2.5 wrenches out of 5.