Volvo 940 only blowing cold air

[McGandalf]

Originally Posted by Laird Scooby

I'm pretty sure you missed "Remove the bottom hose from the bottom of the rad to drain off excess water from the rad and block and then refit - having a new Jublee clip for it is a wise move as they often rust." from just past the green section above.

That would have made room for more than 4L of coolant!

No - I did remove the bottom radiator hose and a large amount of water gushed out. Sorry if I didn't make it clearer earlier.

I'll trace the heater matrix/coolant hoses when I can have a look here. Chucking it down here in grim old Sarf London - at least next door's cat won't be in any danger of lapping up the tasty ethylene glycol which flooded the driveway earlier!

[Laird Scooby]

Originally Posted by McGandalf

No - I did remove the bottom radiator hose and a large amount of water gushed out. Sorry if I didn't make it clearer earlier.

I'll trace the heater matrix/coolant hoses when I can have a look here. Chucking it down here in grim old Sarf London - at least next door's cat won't be in any danger of lapping up the tasty ethylene glycol which flooded the driveway earlier!

Then you should have had room for at least 5L of antifreeze and 3-4L of water on top. Something strange going on from the sound of things.

The heater hose that you trace back to the inlet manifold/head should go to the bottom bulkhead connection if my memory isn't playing tricks, the top stub on the bulkhead is in fact the lower of the two connections to the matrix but the top appears lower because of the valve extending it.

Worth swapping those two connections if in any doubt. Do it quickly enough and you'll lose barely any coolant.

At least the rain will wash away any evidence for you!

[AllHailKingVolvo]

**EDIT - I posted this in reply to an archived version of the post on my browser-please disregard!**

Another vote for stat issues being at the heart of the problem. Out of my seven 2/7/900 series cars, I’ve changed the stat on four of them as they weren’t getting up to full temp. My diesel 940 was totally transformed by a new stat and drives SO much better now. And gets properly toasty with the cabin heater on, too!

A stat is around a tenner and dead simple to change. Slather the stat cap on the car in penetrating fluid as suggested, leave it for a day and spin the nuts off, swap the stat and reassemble. Check torque settings on the nuts when reassembling...I learned this the hard way with my first 940 and snapped a stud by neglecting to use a torque wrench...don’t do that!

[McGandalf]

Thinking aloud now - I haven't had a chance to do much more tinkering since I refilled 4 litres of coolant, found more wouldn't fit and the vents were still blowing out cold air…

I then came to remove the hoses feeding the heater matrix through the bulkhead, only to find I couldn't access the jubilee clip on the lower hose - 7mm flexi head ratchet spanner since bought, yet to be used.

Could the heater matrix itself be shot, or blocked? I know a common symptom of a bad matrix is coolant pooling in the cabin footwell - which I don't have - but can the matrix still be the culprit? Are they available new?

Is there some pesky fuse I'm overlooking? Haynes says fuse 16 powers the air conditioning (none fitted) and "heater blower" - the blower itself turns over, but no heat comes out.

[McGandalf]

Originally Posted by AllHailKingVolvo

Check torque settings on the nuts when reassembling...I learned this the hard way with my first 940 and snapped a stud by neglecting to use a torque wrench...don’t do that!

Out of interest, what are the required torque settings for the 'stat housing nuts? Haynes doesn't say.

I tightened mine to "reasonably tight" and was obviously lucky that they didn't shear off!

[Laird Scooby]

Originally Posted by McGandalf

Thinking aloud now - I haven't had a chance to do much more tinkering since I refilled 4 litres of coolant, found more wouldn't fit and the vents were still blowing out cold air…

I then came to remove the hoses feeding the heater matrix through the bulkhead, only to find I couldn't access the jubilee clip on the lower hose - 7mm flexi head ratchet spanner since bought, yet to be used.

Could the heater matrix itself be shot, or blocked? I know a common symptom of a bad matrix is coolant pooling in the cabin footwell - which I don't have - but can the matrix still be the culprit? Are they available new?

Is there some pesky fuse I'm overlooking? Haynes says fuse 16 powers the air conditioning (none fitted) and "heater blower" - the blower itself turns over, but no heat comes out.

I doubt a ratchet spanner will get on a Jubilee clip, a 7mm socket with a 1/4 drive and a 1/4 ratchet will though. Matrix might be blocked but shouldn't be after reverse flushing. Maybe the valve is siezed shut, can be bypassed with a short length of 15mm copper water pipe but obviously a bit messy doing that in the footwell. Also check some bright spark hasn't fitted a 15mm domestic isolation/service valve in the engine bay to cut the feed to the heater.

Just the one fuse for the heater blower on the manual heating system, the rest is all mechanical operation.

[Ian21401]

My two pennorth, for what it's worth. Some of it may be useful. Please feel free to disregard if it doesn't help.
I have no knowledge of your B230F engine as mine is a B200F, non turbo and no AC but the heater and hoses etc. may be similar to yours.

My coolant system capacity is 8.5 litres. I suspect that yours may be more than that. As you drained more than 8 litres of coolant out then it is obvious that you should be able to replace a similar quantity and if that amount drained out it would appear that the HCV was open and the heater matrix drained. After flushing etc. you were only able to replace 4 litres into the expansion tank and that after running the engine it is still not possible to refill any more than there is obviously a problem somewhere. I think that I would be inclined to go back to square one and try another complete drain, including the drain on the side of the engine block.
When you do eventually refill the system do it very slowly.

You have mentioned that the dashboard heater control will not move to the cold position. Whilst the system is drained I would check that the HCV is operating correctly by disconnecting the HCV cable from the HCV lever and checking the movement of the valve. I cannot remember the orientation of the valve on the bulkhead but here are two images, one with the valve open
and one with the valve closed, of the old valve which I had to replace several years ago. (More of that later)








Re the heater hoses,
On my car there are two heater pipes through the bulkhead. The lower one is part of the moulded plastic body of the HCV. See the below image.





There is another hose inside the car connecting the HCV to the heater matrix.
I would not try to remove the lower hose from the HCV pipe unless it is absolutely necessary. The HCV in the image is one that I removed several years ago because of a leak I found shortly after acquiring the car. The leak was eventually traced to the fact that somehow that plastic pipe had beeen deformed, probably by overtightening of the hose clamp, so that it was no longer cylindrical. See below images.











That hose attached to the lower heater pipe (the HCV), the one which is very difficult to access, bends behind the engine block and continues behind the block to the inlet side of the engine then does a U turn to join a stub on the engine block under the inlet manifold under no. 4 injector. I consider this to be the inlet side of the heater system. If you wish to disconnect that hose I would advise doing so where it joins the engine block. If you must disconnect the hose from the HCV pipe I suggest releasing fluid first then, as Dave suggests, a 1/4" drive socket, extension and ratchet but be very careful not to put too much strain on the HCV pipe whilst doing so.
The hose attached to the top heater pipe also bends behind the engine block, does a U turn whilst still behind the engine block and is joined to the metal rigid pipe which runs under the exhaust manifold to the back of the water pump. I consider this to be the return pipe from the heater system.

Re the tightness of the thermostat housing nuts.
I don't have a torque figure either. After cleaning the stud threads I lightly oiled them then wound on the 10mm flange nuts. Tightened them with the ring end of a small combination spanner until they just felt tight with the open end of the spanner pressing into the cushion of the palm of my hand, then another small tweak. a small spanner used to reduce the amount of torque available. Checked them again the next day after using the car. Once tightened smear some grease on the exposed threads of the stud to prevent corrosion causing problems when they next have to be removed.

Viscous Fan.
I had engine warm up problems last year which were eventually traced to a broken thermostat.


t=overcoolinghttps://www.volvoforums.org.uk/showthread.php?t=301913&highligh



But whilst attempting to trace the problem I suspected the Viscous Fan. With the engine cold I was able to spin the fan a 1/4 turn. I had been led to believe that it should spin much more freely, more than one revolution. I obtained a new OE hub (Volvo name it as a "Slip Clutch" ) and upon comparing the resistance of my old one againsgt the new one found that they were the same, so the old one is still on the car and the new one is in store.

Heater Blower.
The heater blower is simply that, a fan. there is no physical connection between it and the heater matrix, HCV or coolant so it will not have any connection with your current problem.


Edit:
The thread link hasn’t worked so I’ll try that again later.

https://www.volvoforums.org.uk/showthread.php?t=301913

That's better.

[Laird Scooby]

Originally Posted by Ian21401

t=overcoolinghttps://www.volvoforums.org.uk/showthread.php?t=301913&highligh





Edit:
The thread link hasn’t worked so I’ll try that again later.

https://www.volvoforums.org.uk/showthread.php?t=301913

Is that the one Ian?

[Ian21401]

Yes. Thanks Dave. Got there eventually.

[Laird Scooby]

Originally Posted by Ian21401

Yes. Thanks Dave. Got there eventually.

You're welcome Ian, i've noticed quite a lot of thread links (and other links) have got corrupted on here lately. Can't remember which thread but someone had posted a link to an ebay item and it first of all came up with "Error 404" then second time of trying it took me to a site Firefox wouldn't let me open due to dangerous content.

I managed to extract the item number from the link that had been posted and searched for that and the OP on that thread confirmed that was the item - also the link hadn't worked for them that they posted. Weird!