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

[kiloran]

Originally Posted by kelvinp

Temperature gauge at 11:30 and dropping when you put the heater on full, then I would go with thermostat failing. It's either stuck partially open or opening too early.

The symptoms with mine were the same, there was a noticeable drop in the temperature gauge needle when I was doing fast driving. Around town I didn't really notice there was a problem as it was only short runs.

I'll be blatting it up the M3/A34/M4 tomorrow so will keep an eye on it. Have to love how 70mph is vertical on the speedo too, typical Volvo.

[Laird Scooby]

Keep an eye on the temp gauge as you hit the M27, if it starts to drop as you get up to motorway speeds you'll know for sure the 'stat is weak.

Many moons ago there was a design study on gauges (i think for the aerosapce industry) and it was found that the vertical position of gauges was the most easily read and recognised as being right.
Could get you into trouble round town though!

[AllHailKingVolvo]

I changed the HCV in my old 240. Absolute sh*tter of a job, and the one I fitted was defective, so sprayed the inside of the car with a fine mist of coolant!

Out came the defective unit and in went the old one, then out came the old one and in went a decent new one. Problem solved. Never again...most of my knuckles are still in the car!

[Rversteeg]

The temperature gauge is quite heavily dampened around the middle position, so it is not a lineair scale. I have seen some measuring results indicating that the needle stays more or less at 12 o’clock from 60 to 120 degrees! An 11.30 position is therefore considerably colder than you would expect. You will certainly notice this in the heater performance.
Rob

[kiloran]

Originally Posted by Rversteeg

The temperature gauge is quite heavily dampened around the middle position, so it is not a lineair scale. I have seen some measuring results indicating that the needle stays more or less at 12 o’clock from 60 to 120 degrees! An 11.30 position is therefore considerably colder than you would expect. You will certainly notice this in the heater performance.
Rob

Interesting thanks. On the run today it never got to 12 o'clock and on a couple of occasions it was down around 11 (lower than it is normally). The only time it was almost vertical was a max load test going up over White Horse hill near Avebury (motorways were screwed so I went cross country). For that test I arrived at the bottom at about 20mph in 4th gear and climbed at max load until the car got to 50mph. Once over the top it almost crept to vertical but still not quite and quickly dropped back to 11.5ish. Its a test I did in my old Mondeo diesel when it was having cooling issues so hopefully valid for a petrol car too.

Heater symptoms in the car - barely warm air from the drivers window, drivers hand vent, and windscreen vents with the selector on screen or upper. Cold air from the centre dash vents. On the screen heat setting it was still warm enough to keep the windscreen from misting. It was pretty cold first thing - I had to scrape the screen this morning. One thing I was getting was condensation on the outside of the windscreen in line with the dash screen vents. Thought it was inside until I used the wipers and it cleared.

On arrival in Swindon I checked the rad hoses. Top hose was definitely hot to touch but wasn't scorching. Didn't have time to check for any leakage from the HCV, will do that when I get home tonight.

Anyway, stat is on the way and I'll look at it at the weekend hopefully. Thanks for your help with this, as a first time poster it's really appreciated and I'm loving finding out about the quirks of my new car.

[Laird Scooby]

The 'stat will definitely improve matters for you! Also check your viscous coupling on the fan hasn't seized.
When the engine is cold (and off!) you should be able to spin the fan easily, get the engine hotter and switch off then try again, it should be considerably harder to turn.

Must admit, i think you made the right choice on the route, i would have opted for the one you took in the first place and avoided the motorways completely.
If the hill you're talking about near Avebury is the one i'm thinking of, if that didn't make the engine work and build temperature, nothing will!

Don't forget today has been cooler than it has been in general lately which would have probably caused the 11 o'clock position instead of the 1130 position of the temp gauge.

It's a while since i did a 'stat on a red block and i can't remember the sealing arrangement. If it's a sealing ring (rubbery thing) there should be a groove on the inside to fit on the 'stat. If so, smear the edge of the 'stat with silicone grease (or Vaseline at a push) and once the 'stat is in the ring, smear more on the outside of the ring.
When you've removed the old one, clean out the recess in the head and 'stat housing that the 'stat sits in using a flat bladed screwdriver or similar. Put the 'stat in place, twist it left/right a couple of times to get it seated then fit the 'stat housing again.

[griston64]

Be careful with the nuts on the housing as well. The rubber gasket fits round the edge of the stat. Clean all mating faces very carefully before refitting.

[Ian21401]

kiloran,
I have a 1992 940. The central facia vents are only designed to provide air at the ambient outside air temperature, so mine are closed except in the hottest of weather. The side facia vents are designed to provide air heated to whatever you have the heat control set to.
Decades ago I drove a 244 provided by my employer. I cannot remember whether it had central facia vents but the side facia vents were fitted with a mixer adjustment so that it was possible to control their output temperature between cold and whatever the main heat control was set to. Dave may be able to confirm that.
I’m in the process of sorting a problem very similar to yours. My viscous fan appears to have seized so I have removed it temporarily and will soon be fitting a new thermostat.

[Laird Scooby]

Originally Posted by Ian21401

kiloran,
I have a 1992 940. The central facia vents are only designed to provide air at the ambient outside air temperature, so mine are closed except in the hottest of weather. The side facia vents are designed to provide air heated to whatever you have the heat control set to.
Decades ago I drove a 244 provided by my employer. I cannot remember whether it had central facia vents but the side facia vents were fitted with a mixer adjustment so that it was possible to control their output temperature between cold and whatever the main heat control was set to. Dave may be able to confirm that.
I’m in the process of sorting a problem very similar to yours. My viscous fan appears to have seized so I have removed it temporarily and will soon be fitting a new thermostat.

If memory serves Ian, the centre vents on manual heaters are for fresh air, the outboard ones can be set to whatever temperature the hear is set at.
On air-con cars, the centre vents and outboard vents are designed to be left open, especially in Auto mode whre the system selects the outlets (vents, feet, screen etc) and the air blend to match the set temperature. If set to the screen or the system in auto mode senses the screen needs demisting, it will set full heat, fastest fan to the screen, no other output.

I can't remember what the 240 estate i had as an occasional company car had in the centre, vents, no vents, fresh air only or temperature controlled - could be any of them! Usual chariot of choice was a 360 GLT and i only had the 240 if the 360 was either in for service or some other reason.

[kiloran]

Originally Posted by Laird Scooby

If memory serves Ian, the centre vents on manual heaters are for fresh air, the outboard ones can be set to whatever temperature the hear is set at.
On air-con cars, the centre vents and outboard vents are designed to be left open, especially in Auto mode whre the system selects the outlets (vents, feet, screen etc) and the air blend to match the set temperature. If set to the screen or the system in auto mode senses the screen needs demisting, it will set full heat, fastest fan to the screen, no other output.

I can't remember what the 240 estate i had as an occasional company car had in the centre, vents, no vents, fresh air only or temperature controlled - could be any of them! Usual chariot of choice was a 360 GLT and i only had the 240 if the 360 was either in for service or some other reason.

Aha - that has to be one of the stranger quirks I've encountered. Can't recall any of the 15+ cars I've owned delivering cold air from some vents whilst others are delivering hot.

Further diagnostics - passenger side outer vent is warmer than the driver's side outer vent. And the glovebox is noticeably warm based on the slightly melted Twix I found this morning

Still waiting for stat to arrive.