In this recently bought 2000 volvo, I don't understand why the heat worked most of the times, @ 50%.
Ocassionaly....80%, sometimes 30%...and now it has quit..almost like 5 %.

Interestingly when outside was 60 F on Sat and Sunday...by setting at 80F, I got very good heat.Had to open the windows to stop cooking myself, but didnot wanto disturb the set temp.
I left the settings undisturbed...on Sunday night.
Monday morning when I needed heat there was NOTHING...not even 5%.
Since then tried everything to set temp lowest highest, put on auto fan, auto duct...but nothing.
Yesterday as the timing belt was changed, so was the Water pump, and hence new Volvo coolant installed. No heat.

Some feel its the sensors which open flaps in front og the heater core which is always fed hot water...!
Os it true...?
In most older cars, a separate valve opens the hot fluid to the core[which sits next to the AC core], on selection of the temp, higher than ambient, or inside.
In these 2000 Volvos with auto climate control, I am told there is no such valve...so it can be a sensor issue...

Need opinions and advice..

Thnx

 

The first thing I'd do is clean the air temp sensor behind the center console.

See the small horizontal cuts in the center console just under the cup holder? Behind that is a small sensor which pulls air in. It gets filled with dust over time.

And I'm no help on the heater control being a flapper door for air or a water temp valve. I have 2 Hondas with the water temp valve and 2 GM cars with a the air flapper door. I also have 2 Volvo S40's with ???? (I would like to know too)

 

How is your cooling system? Make sure your coolant level is good. Also, a stuck open thermostat could prevent the engine form warming up properly and producing heat on a cold day. If this is the case then it should eventually throw a code.
Stan

 

Thnx for the posts.

Yes I notice the two slitted intakes for the sampling of air temp..wonder how do you access the sensors.
Also since these are two, I am not sure if they both go bad together, or more importantly, why just three days ago,the heat has gone to 80% good down to 20 %, and now finally quit.
It does seem though, a sensor going bad and finally quit...maybe some other sensor, since there are five.

Now on the stuck thermostat, I would think it to allow the hot water to goto the htr. core,,,and if non-stuck, should open 'after' the engine has heated to its operating temp.
The coolant and the pump ve been replaced 2 days ago...and problem existed before.

I wonder if there is a way to see if the htr core indeed gets hot[gets the coolant flow].

Thnx again.

 

I just remembered something when working on these cooling systems. It is fairly easy to get them air bound. As I recall there should be a red bleed valve on one of the hoses to let air out of the system. I believe it is on a hose on the transmission side of the engine bay. Don't open it when the engine is hot.
Stan

 

When new coolant was installed, system was well bled from that red button-like screw or plug. There is no more air in the system..its that dogone...fancy climate control automation/modernization whatever ....that 'requires complexity'...and hence comes the decline/loss in reliability,,,I ve known as an engineer for the last 20 yrs.

Who really needs the auto climate control...and then talk about separation of temp correction for passenger and for the driver...as if two deg temp difference between them sides, will freeze or broil the driver or the passenger.

Ive this called Volvo 'BASE' model...I wish they had left the AC and Heat as 'base'[basic] also, as was in 90's.....let me control it....and you save some chunk on the cost of the car,and the sticker price !
And leave the coolant flow control valve for the heater ....under the hood so if its clogged or refuses to operate[like in Audi 100 of 1991]...I could change it w/o removing the darn dash board.
SO TO THE DESIGN ENGINEERS YOU CAN NEVER OVER EMPHASIZE..KISS[Keep it simple stupid].

Have you heard of those fancy auto regulating suspension systems...the darn sensor senses the road roughness and adjusts the strut/spring stiffness...?
Well many owners now realize the cost of replacement of these, from BMW 850 to the fancy Lincoln is prohibitive....some say $3000.
I will rather see a hole in the darn strut than a hole in my pocket to buy such a design and then pay to repair/replace it.
Then the owners of these cars wonder why suddenly after 100k the value of the car drops to 40%..well many buyers are wise.

Thnx

 

It very well could be a faulty climate control unit. I have heard of them going bad in these cars. They usually indicate a fault though and not just misbehave.

When they work, they are nice but when they break....

What is your field of engineering? I am electrical working satellite operation and some design.
Stan

 

Thats what I suspected and needed some one to confirm the commonality of this issue...with Volvos or S40's...so
Thnx for ure comnts.

Some while back the engine light came up and the code was read by Autozone, and for some reason,could not be translated,then I did narrow down that number to a heat related sensor.
I understand there are 5 sensors, most probably it can be the one sensing the heat output from the heater core, OR sensing the inside air temp[there are two I suspect behind the sampling slits, wonder if both CAN go bad.]
Are these sensors RTD type so can simply check their resistance..?

How hard is it to access the htr core area...these Volvos are new to me..have owned 5 Audis and 3 BMWs.

I m a ME with lot of work done in design of OPer Rm Equipment related to surgery and Infec control...Im now semi-retired.

Nice to see someone with EE and Volvo ownership...

[Oh..the speed IS needed to create the momentum..badly needed for the impact.. LOL !]

 

I wish I could answer your question about the core and I never has need to look into the sensors. While Volvo doesn't sell shop manuals for these cars, Haynes does in the UK. You can buy them here through IPDUSA.com and probably other places too. The other option is if you can get a hold of a VADIS disk. It has the manuals for all Volvos from 1975-2005. They are intended for dealer shops but they show up on auction sites.

Another good resource that I just remembered:
http://www.matthewsvolvosite.com/volvo-wiring-diagrams

Speed only enhances the impact.
Stan

 

There is a VADIS seller on ebay from the UK. Pretty decent price for models up to 2004.

 

Any update?

I ask because my 2005 has started doing the same thing. No heat, some heat, lots of heat, you never know. I suspect it's the cabin temp sensor as I replaced the ignition switch and had to disconnect that sensor to remove the panel behind the radio. I finally got home so I'm going to have a look.

 

Update of my own. I recently bought VIDA 2010B via ebay. I finally got it to work on an old windows xp laptop after I found the right patch file online. (The patch with the disk did not work for xp. Don't know why.) After much searching I found that the S40 has air doors much like my GM vehicles to direct air in the right spots. Unlike my old cars the S40 has little electric motors to move those doors. And some doors are known to break the tab that connects the motor to the door. The 2000-2004 and 2004.5+ use the same concept but the design is different. I really recommend VADIS for the older Volvos and VIDA for the newer. I hear VIDA 2010C with patch will work with windows 7. Rumor tho.

I'm still in the diagnostic phase on my 2005. It has two "Damper Motor Module"(s) for temp control. One for the driver's side temp control and one for the pax side temp control. VIDA says "see Dash Removal" for replacement. That sounds bad. We will see.

 

In the 2004.5+ the servos can get out of sync and cause weird problems with the HVAC (ie. one side blows hot, the other side cold and other odd problems). If this is the case, it takes a software reload by Volvo service to correct.

Mine did this while under CPO warranty and it was fixed for free. I don't know what they might charge out of warranty. Mine has been good ever since the software fix.
Stan

 

I could definitely see that happening. I'm lucky it was not the problem in my case as I'm long past the warranty period.

After removing the kick panel under the steering wheel and radio I played with the climate controls. You could clearly hear the door motors moving and what sounded like the doors themselves. Time to check elsewhere.

I had read another thread where the car was over-cooling due to a bad (open) t-stat. This lead me to look under the hood at the overflow tank where I found the coolant level low. So I topped off the overflow tank and the heat worked! Never had that problem before so now I know where to look first.

 

Thnx.

Suspecting the control system, I checked the flap-operator behind the radio[easy to remove]...it functions perfect by setting temp from 82/high to 40/low . So if there is no valve to control the coolant flow, and the flap is 'the guy' to control the temp, then I tend to assume the controller is working fine. And AC works fine[as I m told the core or evaporator for it is placed away from the ht core].
So now I need to disconnect the two lines going thru firewall[to the htr core inside], and plug the engine side and see if I can get the flow out of the htr core, now separated from the engine. I can then back flush, put some CLR, and the re- flush etc etc.
When I changed the coolant a yr ago, it was ridiculous...like orange with rust floating all over..like some one put a special oxidising compound in it...or oxygenated water for God's sake.
So if the damage is done, its to the core probably. The water pump recently changed was quite clean to my surprise.

But can some one confirm that indeed there is no htr valve to control coolant flow...?
sounds odd because w/o the valve ...the hot coolant is always dumping heat into the inside core [hoping the flap will 'totally ' cut it off], during warm/summer weather when AC has to work hard to get rid of the heat.

 

"Any update?

I ask because my 2005 has started doing the same thing.
No heat, some heat, lots of heat, you never know.
I suspect it's the cabin temp sensor as I replaced the
ignition switch and had to disconnect that sensor to
remove the panel behind the radio.
I finally got home so I'm going to have a look."....Hudini
.......................................
I just posted an update, but am curious if behind the radio you
CAN see the motor operated flap, 'move'
when you set/change the temp from lowest to highest.
If it does, then would you still think its the sensor..?
[Now ..there are four/five sensors I m told].

I would think the sensor feed to the control unit decides if the
flap hasto be moved based on the difference between the inside temp[sensed],
and the set temp[ by the control ****].
Like to know what you found.

I m pretty sure the problems in a design remain consistent over a
large population of production for a specific model/year.These manufacturers very rarely go back 5-10 yrs to see a problem, and help the previous owners...trye they just take the complaints and try to eliminate that in the newer models.

This is why a forum helps a lot to a common-problem-car owner..more than the darn dealer can.

 

I bought the VIDA 2010B and it shows no water valve, only air doors. You cannot see the air door moving as it's behind the dash and buried inside the climate control unit. You can hear the electric door motors though. If the doors move then I'd look elsewhere.

Have you checked the heater hoses to see if they get hot?

 

thnx..
Well I can see a plastic arm/link, turning an axle, which internally is turning the flap enclosed in the duct.What else should operate that if not the temp extreme settings...asking from full shut to full open.
What I didnot verify is if the link is spinning free on the axle..tied to the flap which then will not move even though visually the link is saying so.

Yes the lines/hoses going to the htr core ...are at diff temps, almost suggesting no/little flow.

I ain't changing the core...that damn dashboard.
..........
On a diff sbjct:
Hey from VADIS, can you interpret the engine check fault code..
[I just got the light]..
The code given tome by Autozone is:P0014, related to cam shaft sensor.

I don't know if that means sensor is bad or camshaft itself has its timing messed up due to something else say..loose T Belt..jumped

Now where is this sensor located...and is it resistive or has a coil with an impedence. Before I change that..expensive sob, like to confirm its failure.

Thnx

 

After the code was read, now the engine check light is gone.
Is that normal..?

Interestingly...when the E Chk L was on, my mpg went down from 25 to may be 19/18...and the exhaust was smelling bad/weird.

How bad is the cost of this sob...and what is the good source to order a good one.

Thnx

 

Do you have much crud in your cooling system that might clog your heater core? I figure that this is very unlikely. I am also surprised that there is no water control valve but then Volvo does some tricky things.

I have heard of cam sensors going bad. The engine may go into limp mode which will impact performance, economy and emissions.
Stan