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V70 1997 Heater problem

Help, Advice and DIY Tutorials on Volvo's extremely popular car line -- Volvo's 1990s "bread and butter" cars -- powered by the ubiquitous and durable Volvo inline 5-cylinder engine.
1992 - 1997 850, 850 R, 850 T5-R, 850 T5, 850 GLT
1997 - 2000 S70, S70 AWD
1997 - 2000 V70, V70 AWD
1997 - 2000 V70-XC
1997 - 2004 C70

V70 1997 Heater problem

Postby rohosub » 28 Feb 2006, 12:24

Hi, folks.
I'm kind of a newbie here and I don't know much about cars. I'm an IT consultant. That probably tells you a lot. :D

I've had a Volvo V70 1997 2.0l for 7 years and had no problems with it at all. I've never missed a service. It has currently run almost 180.000km.

Recently I noticed that the heater was supplying less heat than normal and this has gradually worsened. I'm from Norway and we have winter at the moment and I tell you. When it's -15 degrees below zero (celcius) you really need a working heater. At the moment the heater supplies little to no heat at all. The AC seems to work normally supplying cold air and removing humidity. At least that's what I think. It's winter...

I've checked the coolant. This seems to be at the right percentage and level.

Could someone please give me a hint as to what could be wrong?

I've had no problems with the car until now. It is currently using a little bit oil, but not in large quantities. This is probably normal on a 9 year old car during winter, but I'm not sure.

Hope to hear from you guys.

Kind regards

roho
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Postby White850Turbo » 28 Feb 2006, 13:06

On your instrument panel, where does the temperature needle stay at once the car is warmed up? If it moves at all once the car has been running for at least 10 minutes or it doesn't get to the "horizontal" position, the most likely problem is that the thermostat has failed. This is an easy item to replace. There is a guide somewhere on this site on how to do it on one of the drop down menus.
-Sean

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Postby rohosub » 28 Feb 2006, 13:18

Hi.
Thx for your reply.
The temperature needle rises normally to horizontal position after a few minutes and stays there.

I've seen the previous thread regarding replacement of the thermostat but I'm not sure this could be the problem as long as the cooling of the engine seems to work.

roho
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Postby White850Turbo » 28 Feb 2006, 13:23

Hhmm, does the car have the auto climate control (where you set the knob to a temperature) or is it manual? Do any lights on the climate control panel flash when you first turn the car on?
-Sean

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1998 S70 T5 (Almost Stock)
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Postby rohosub » 28 Feb 2006, 13:36

I have the manual one and no lights are flashing when I start the car.
The only lights that could be flashing would be the green light on the AC and/or the yellow light on the re-cycle, right?

roho
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Postby pfeener » 02 Mar 2006, 02:23

Let's see if we can cut the problem in half. Based on what you said about the temp gauge coming up to the normal 3 o'clock position, it appears the coolant is coming up to the normal temp. The coolant should be running through the heater core in the bottom of your center console. After the car heats up to normal temp, feel the heater hoses going through the firewall from the engine comparment. Both lines should be hot. If one is hotter than the other you have a blockage in your heater core. If both lines are hot the heater core is OK and you have an issue porting the air through the ducts in the dash and through the heater core to heat the air.

The heater hoses should be at 90 degree C. Which is close to boiling and too hot to hold your hand on the hose for very long. If both hoses are only warm or you can hold your hand on the hose for a long time, it's not hot enough.
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Postby pfeener » 02 Mar 2006, 02:26

One more question. Does the fan come on high as the engine temp heats up. If not, can you put the fan on high manually and if so does it blow hot air.
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Postby rohosub » 02 Mar 2006, 12:53

Hi, Pfeener.
Thx for you reply. This was interesting. I've now taken the car for a 20 min drive to be sure everything was heated up properly.

None of the two hoses you mention reach 90 degrees (celcius). They are not that hot. I'm barely able to hold them. They pass through the firewall above each other. The lower one seems to be the hottest one, but I'm not quite sure.

I've also done some research on the heater itself. If I turn the fan on max with both sides (driver & passenger) on the hottest. With the airflow set to blow into the coup
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Postby pfeener » 03 Mar 2006, 01:52

My bad on the manual fan control. I thought it was an automatic climate control system. If the heater core temp is only coming up to partial temp, you won't get any hot air. The water has to be flowing through the core and be at full temp to get hot air. If you can hold onto the heater hoses without burning your fingers and one is hotter than the other, it sounds like you may have a partially or fully clogged heater core. The heat you feel at the hoses may just be from the hot water in the engine block. It may not actually be flowing through the heater core. Try this to prove it to yourself. Start up the car from a cold start and feel the heater hoses as it warms up. They should start out cold and warm up at the same rate as the water in the engine block. If the engine is fully up to temp and the heater hoses are still luke warm, that's a pretty good indication. Here's a link that shows the heater core and how to get at it to examine it or replace it. It for an S70, but it's the same as yours after you get past the console covering.

http://volvospeed.com/vs_forum/index.ph ... eater+core
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Postby rohosub » 06 Mar 2006, 12:50

Hi, Pfeener.
Thx a lot for your insight last week.
I've done some serious error checking during the weekend and would like to run my thoughts by you.

During the weekend I've emptied the radiator and cooling system. I added the combination of radiator-clean and water. Drove around for about 30 minutes and flushed the system again. Disconnected the hoses to and from the heater core on the engine side and flushed the core with clean water. Also flushed the engine side of the system. At last I disconnected the hose from the thermostat to the radiator and flushed the radiator it self with clean water.

After doing this and refilling with coolant I'm now able to get some heat. I get heat from the system if I run the engine on 3000 RPM or more. If the RPM drops to 2000-2500 during normal driving the heat disappears.
Could this be because the water pump delivers more pressure or heated water on higher RPMs? When I get heat it's now mainly on the passenger side of the coup
Last edited by rohosub on 06 Mar 2006, 23:24, edited 2 times in total.
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Postby pfeener » 06 Mar 2006, 22:01

Sounds like you're making some progress. I wouldn't replace anything just yet. If we sit back and analyze the problem; after you flushed the system, the problem got somewhat better; which says to me you have a clog somewhere because if the system had been free and clear to start with, flushing it wouldn't have done anything at all. Also the fact that one of the heater hoses is hotter than the other says to me that you're not getting the volume of flow through the heater core that's necessary. There's not any mystery in the system itself; the antifreeze flows out of the hose which is plugged into the cylinder block and flows into the top heater hose connection, flows through the heater core unobstructed (no valves to shut off the flow) back out the bottom hose and into the return flow from the bottom of the radiator and back to the pump. Having said that, here's what I would suggest; 1. flush it again with a flush agent that you can leave in longer. Some flush agents are made to stay in for a few hundred miles. 2. If that doesn't do it, I would consider changing out the heater core. It's a good sign that you can flush a hose through the heater core, but it doesn't necessarily mean it's OK. The heater core is built like a mini radiator in that the water flows into a tank on one side of the core and then through a couple dozen small tubes to get to a collecting tank on the other side of the core. If half of the tubes are clogged you'll still get flow through the core, but only half the core will heat up and you won't get much heat.

If you flush it again you might also try back flushing the hoses that feed the heater core just to be sure they are free and clear.

The root cause of the problem could be that the previous owner had a leak in the heater core and dumped in a can of "stop leak" which stopped the leak but clogged the small tubes of the heater core; so even if you get it running free, you may get a leak back in the core anyway.

Just curious; how did the antifreeze look when you flusshed it. Was it relatively clear of did it have a lot of junk in it?
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Postby pfeener » 06 Mar 2006, 22:10

Missed one of your questions again: The water pump is probably the last thing I would suspect. It's just a bunch of vanes spinning around. If the vanes were eaten away (never ever seen it happen) the flow would be affected, but you'd have far bigger problems such as the engine overheating. I still think it's in the heater core and another more through flush may take care of it.

If you order a heater core, the aftermarket cores are a lot cheaper. FCPgroton.com, has a heater core for around $128.
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Postby rohosub » 06 Mar 2006, 23:21

Thx again, Pfeener.
When I emptied the system and flushed it, the antifreeze was greyish and smelly. It didn't look good at all. Even during my second flush grey stuff came out.

I think I'll follow your tip and go for yet another clean/flush routine.
Does anyone know if it is possible to use more potent cleaning agents than radiator clean without damaging hoses, inflicting corrosion etc?
Any chance I could inject stuff like an ordinary "drain opener" into the core itself as long as I don't run the engine? (Just a thought). A typical drain opener would consist of pretty potent NaOH which would eat away at almost evrything (Maybe also the aluminium in the core...?)

If a second drain/flush doesn't work I'll order a new heater core and try the replace myself using the guide posted here.

I'll keep you posed. I might take some pictures as well...

Thx again for your help here. It has been really helpful.

roho
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Postby pfeener » 07 Mar 2006, 00:43

Some people use white vinegar when doing a flush. Here's a link with additional info. I wouldn't use anything like drain cleaner or such. I'd be too scared of dissolving things like head gaskets.

Personally I would look for a commercially available flush that states on the can how long to leave it in and as I said before, I would go for something I could leave in for a few hundred miles.

P.S. If your coolant was grey after the flush I would lean very heavily toward a clogged heater core. You may need to flush a few more times yet.

Here's the link:
http://volvospeed.com/vs_forum/index.ph ... hl=vinegar
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