S70 1999 not heating

jabster97 · Post by **jabster97** » 06 Jan 2010, 19:35

Seems that the heater will just not get warm. Evan after 10+ miles of driving temp barely moves. Almost no heat generated and now CEL has come on and radiator fan runs after shut off. Air temp is in 20's and coolant is full.

chax · Post by **chax** » 06 Jan 2010, 20:26

It's possible that the coolant level is not just low: it’s TOO low. So low, in fact, that air pockets can develop; once an air pocket reaches the water pump, the water stops circulating, and although the coolant gets hotter and hotter, it’s not flowing, so 1) you’ll get very little or no heat from the heater, and 2) the cooling system might very well burst open shortly.

Start the car: once it has run long enough that it should be at operating temperature (maybe 10 – 15 minutes at 20F), CAREFULLY touch the hose that runs from the thermostat housing to the radiator: if the hose is hot, the coolant is much too low: TURN OFF THE ENGINE IMMEDIATELY, AND DO NOT ADD COOLANT UNTIL IT HAS COOLED FOR AT LEAST 30 MINUTES!! Why? If you add coolant to a hot engine (that’s low on coolant), it can eventually seep into an air pocket where the engine is extremely hot, whereupon it will be superheated, turn to steam, and come flying out who knows where. I know a mechanic to whom this happened: he added coolant to a hot engine, and happened to be leaning over the coolant reservoir 10 minutes later, when the coolant apparently reached an air pocket, and the hot coolant shot out of the reservoir and into his face. He’s fine now, but you can see how dangerous this condition can be.

WeAre06 · Post by **WeAre06** » 06 Jan 2010, 20:33

What does the engine temp gauge read after your 10 mile drive?

If temp gauge is still telling you the engine is cold, this means your thermostat is broken in the open position and over cooling the engine. Since the engine never warms up = no heat in cabin

chax · Post by **chax** » 06 Jan 2010, 20:49

It's more often the case that you're not getting heat because the thermostat has failed in the open position.

However, in this case, since the fan's coming on, something must be getting hot, meaning that the problem isn't due to too much cooling. It could be that the thermostat failed in the closed position, which would explain why the fan comes on (the engine's getting hot) AND there's no heat (the coolant exits the radiator, then heads for the heater core [when it's flowing]).

How mechanically inclined are you?

jabster97 · Post by **jabster97** » 06 Jan 2010, 21:08

@chax I thought about too low too. Reservoir is full and radiator has no filler cap. Somehow I think it has something to do with the DEL as now the radiator fan runs even when the engine is not hot.

@WeAre06 I thought about the thremo being stuck open but the egine was getting heat when air temp was in 40's. just not now in the teens and 20's

Going to get a read of the ODBII at Autozone in the am

Post by **jblackburn** » 06 Jan 2010, 21:09

Almost no heat generated and now CEL has come on and radiator fan runs after shut off. Air temp is in 20's and coolant is full.

They're pointing you in the right direction. Your engine coolant temperature sensor has gone bad in addition to the thermostat being stuck open. It's located just under the thermostat there. It's my theory that they break each other when one goes. This is what is causing the fan to run, and the most likely cause of the check engine light.

They're both pretty easy to replace...just drain out some coolant, pinch off the hose to the expansion tank, and unscrew the gasket housing, pop in the new ones, and button it back up!

You will probably want to order new torx screws for the housing - they strip very easily. The new ones are made out of hardened steel instead of aluminum.

I just realized today mine's leaking coolant from somewhere at the bottom of the car after I just fixed that on mine

jabster97 · Post by **jabster97** » 06 Jan 2010, 21:22

@jablackburn

That would make sense. Thanks. I'll look at it in the am.

Post by **firekiller75** » 11 Jan 2010, 08:03

jabster97,
Did you fix your problem? I have the exact same symptoms 90 miles south of you, fan running and everything. Guess I'll be changing out the thermostat and coolant sensor!

Jot · Post by **Jot** » 11 Jan 2010, 08:21

Replace your thermostat as it is open.

Post by **matthew1** » 11 Jan 2010, 11:38

Jot, you're from the Old Days. Long time no see.

Jabster97, if it's thermostat, this Volvo 850/S70/V70 thermostat replacement should get you most or all of the way there. Pay attention to the comments on that page also.