V70 1997 Heater problem

rohosub · Post by **rohosub** » 28 Feb 2006, 05:24

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.

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

White850Turbo · Post by **White850Turbo** » 28 Feb 2006, 06:06

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.

rohosub · Post by **rohosub** » 28 Feb 2006, 06:18

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

White850Turbo · Post by **White850Turbo** » 28 Feb 2006, 06:23

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?

rohosub · Post by **rohosub** » 28 Feb 2006, 06:36

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

Post by **pfeener** » 01 Mar 2006, 19:23

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.

Post by **pfeener** » 01 Mar 2006, 19:26

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.

rohosub · Post by **rohosub** » 02 Mar 2006, 05:53

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

Post by **pfeener** » 02 Mar 2006, 18:52

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

rohosub · Post by **rohosub** » 06 Mar 2006, 05:50

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