940 SE, non-ac, how hot should the heater be?

[kiloran]

New owner of a '93 940SE 2l petrol non-turbo, it's the non-a/c model. Heater pushes out warm air but it's not exactly toasty - how hot should it be?

I've checked around for some of the obvious things as follows:

1. Car warms up in about 5 minutes, temp gauge sits just slightly to the left of vertical

2. Coolant level is fine (not using any coolant)

3. Rad hoses are at the temperature I'd expect I think - after a long run I can hold them fairly tightly indefinitely - should they be hotter?

4. Matrix hoses are warm as they enter the firewall

5. No evidence of any moisture in driver's footwell

6. Blower fan operates on all speeds.

7. Warm air vents respond to the rotary dial selector as expected

8. There is warm air coming from the vents, it just isn't by any means hot. A pleasant heat - I could hold my hand over the vent on maximum heat indefinitely I think.

Is this just how 940 heaters are or is there a problem? I'd always imagined something designed for the arctic wastes would have an insanely hot heater?

[classicswede]

It should be very hot.

Try a new Tstat, you can also flush the water system. The matrix could be blocked with gunk

[Laird Scooby]

Also try reversing the hoses on the matrix, you should be able to do this on the bulkhead. I've had several cars in the past including my last 740 where some numpty had reversed the heater hoses so the flow was in the wrong direction through the matrix resulting in very little heat output and a constant air lock in the system.

Should be pretty hot before the temp gauge gets as far up as you say yours gets but by rights it should sit vertical when up to temperature so it does sound as if you have a 'stat problem as well. That said, you should get warmth - also check the control cable hasn't come off the heater valve, use an old door mirror glass and a torch to see what's happening with the valve and control cable - it's sort of above and left of the clutch pedal inside the car.

[kiloran]

Thanks both, will try the stat as it looks easy enough to do and I don't know the provenance of the coolant in the car. Then will take a look at the control valve/cable

I'm a bit nervous about back-flushing the matrix so will leave that to last. Don't want to accelerate its decline if its on the way out.

[Laird Scooby]

Originally Posted by kiloran

Thanks both, will try the stat as it looks easy enough to do and I don't know the provenance of the coolant in the car. Then will take a look at the control valve/cable

I'm a bit nervous about back-flushing the matrix so will leave that to last. Don't want to accelerate its decline if its on the way out.

https://www.volvoforums.org.uk/showp...44&postcount=5

Have a look at the flushing method described in that post ^^^^^ just ignore the references to the head gasket.

Before you get too far into it, i'd swap the hoses on the heater as a first try to see if that brings hot air from the heater. If so, flushing everything will improve matters and prollong the life of everything.
The flush can be done as part of the 'stat change as well

[kiloran]

Top advice, thanks. Definitely changing the coolant, the expansion tank just contains what looks like clear water, certainly not the blue or orange I'd expect. Got a long run tomorrow (150 miles) so will schedule it for the weekend

[Laird Scooby]

Originally Posted by kiloran

Top advice, thanks. Definitely changing the coolant, the expansion tank just contains what looks like clear water, certainly not the blue or orange I'd expect. Got a long run tomorrow (150 miles) so will schedule it for the weekend

I hope it's not orange or red - that would suggest OAT coolant which isn't good news!

Seriously, try swappinghte hoses on the heater, takes about 10 minutes tops to do it, if it doesn't improve the ehater it's only a few minutes to swap them back again. Might give you nice warm tootsies tomorrow instead of getting out with your feet like blocks of ice!

[TonyS9]

Have to admit my 940 heater isn't the best compared with the 360. Seems to have a poor output for longer that I think it should have.

I generally put the fan up to position 2 after the gauge starts to move, which seems to help.

Once its going about 10mins and a decent rpms it seems good.

I did put a new control valve in many years ago. It wasn't closing due to the hose being over tighened and distorting the housing, so I suspect it might have had a new matrix or something before.

[kiloran]

Update:

Given the hose clamps for the matrix a liberal spraying of release oil as they're pretty corroded.

Removed the kick panel under the steering wheel (yay, torx screws into proper brass ferrules rather than use once, break once plastic clips) and can confirm the following:

1. Heater position switch is connected - arm moves when moving selector

2. Heater control valve connected - can see the cable pulling the arm when moving the heat level selector.

Some evidence of leakage from heater control valve (HCV) - see photos. But it's dry at the moment so might be from long ago.



Got heated seats for the journey tomorrow so not too bothered. And being an almost 50yo Volvo driver, time for driving gloves perhaps!

What's involved in replacing the HCV for a non a/c car? Looks like there's reasonable access?

[griston64]

The worst thing in replacing the heater control valve is getting one !