C43 cooling / heating issues
12-07-2009, 09:39 AM
#1
MBWorld Fanatic!
Thread Starter
C43 cooling / heating issues
'99 C43, having some heating issues. Basically, the heat is only lukewarm, tepid, never blasting hot. It's the same out of all the vents, and regardless of which setting I have the car set to. I have it blasting at HI and full blower motor speed, but still just tepid.
Also, the engine takes quite a while to reach halfway up the needle on temps. Like 20 minutes at least. The only time I'm getting satisfactory heat was a couple days ago, when I was stuck in traffic for an hour.
The temps never really head over halfway - if it does, it's just a smidgen, or when I had to rev the car hard repeatedly to get out of some deep snow, and that was only once. Oh, and it's frigging cold here now too, -25*C. On a few testdrives last night, once stopped, I could touch the valve cover and not get scalded. It was warm, but not really really warm. The electric fans haven't come on.
I replaced the thermostat last night, and no change. I checked the duovalves, cleaned and reassembled, and no change. I then wondered if it was the main fan being on all the time. This is my first Benz and the first car with a main, mechanical fan. Should this fan be on all the time? How does the clutch work, what circumstances turn it on? I just fired up the car and the fan is on right away. When cold and engine off, the fan moves freely, a touch of resistance but no binding or anything.
Any suggestions, do let me know, thanks!
Also, the engine takes quite a while to reach halfway up the needle on temps. Like 20 minutes at least. The only time I'm getting satisfactory heat was a couple days ago, when I was stuck in traffic for an hour.
The temps never really head over halfway - if it does, it's just a smidgen, or when I had to rev the car hard repeatedly to get out of some deep snow, and that was only once. Oh, and it's frigging cold here now too, -25*C. On a few testdrives last night, once stopped, I could touch the valve cover and not get scalded. It was warm, but not really really warm. The electric fans haven't come on.
I replaced the thermostat last night, and no change. I checked the duovalves, cleaned and reassembled, and no change. I then wondered if it was the main fan being on all the time. This is my first Benz and the first car with a main, mechanical fan. Should this fan be on all the time? How does the clutch work, what circumstances turn it on? I just fired up the car and the fan is on right away. When cold and engine off, the fan moves freely, a touch of resistance but no binding or anything.
Any suggestions, do let me know, thanks!
12-08-2009, 01:36 AM
#2
MBWorld Fanatic!
Based on your description, the mechanical fan is working like it's supposed to. If the fan clutch were broken it would either always freewheel (which you won't be able to test until summer), or it would lock up solid.
If you can run AC diagnostics, you may want to display the temperatures of your left and right heater cores (diagnostic displays 03 and 04). Compare those numbers against the coolant temperature (diagnostic display 06). If all three are the same temperature, then the duovalve is working right. If the heater cores are dramatically lower, then I think it's the duovalve. You also may want to check the in-car temperature reading (diagnostic display 01), just to ensure it's working properly.
Don't you guys who live in the bitter cold usually take a piece of wood sheet (or thin gauge metal from a home improvement store) and partially block the radiator for the winter?
If you can run AC diagnostics, you may want to display the temperatures of your left and right heater cores (diagnostic displays 03 and 04). Compare those numbers against the coolant temperature (diagnostic display 06). If all three are the same temperature, then the duovalve is working right. If the heater cores are dramatically lower, then I think it's the duovalve. You also may want to check the in-car temperature reading (diagnostic display 01), just to ensure it's working properly.
Don't you guys who live in the bitter cold usually take a piece of wood sheet (or thin gauge metal from a home improvement store) and partially block the radiator for the winter?
12-08-2009, 11:20 AM
#3
MBWorld Fanatic!
Thread Starter
Thanks for your help (again!). I tried out the diagnostics. For some reason, there is no 04 display. The software and hardware version looks to be v.3. And there are about half a dozen more diagnostic displays past 42.
At any rate, after only a short 10 minute drive (but after about 10-12 minutes of idling this morning in the garage), I get 72*C on the engine temp (per display 06) and only about 29-30*C on the core (display 03). Taking your advice, I called up my engine builder (who I buy lots of parts from as they get jobber pricing) and ordered the only remaining heater control valve / duovalve in town. Actually, in the country, as the parts supplier (altrom.com) deals across the country. I can return it if I need to. I will do a longer drive tonight when I'm out and about, and will run the diagnostics again.
Mucking around with the duovalve before (the disassembly and cleaning, per your site), it looks like a pretty simple R&R? One hose on the front side, a couple on the back/bottom side. There's room to clamp the hoses, I think, and then just release the hose clamps to get it out?
When I did the thermostat on Sunday evening, I was *****ing and cursing about how difficult it was to access it. On my Saabs and my Volvo, I could have it done in about 2 minutes. I took me about 2 hours on the AMG, fiddling with torx sockets and a variety of extensions and ratchets. But on my Saab, the heater valve would involve contortions underneath the dash...
Oh, and I did try blocking the rad too. I had some leftover plastic sheet and I blocked out half the rad. Didn't help that much. It's currently -25*C and I wished my parents had immigrated to California instead. Every winter when it gets cold I threaten to move to the Bahamas. Can never follow through though....
At any rate, after only a short 10 minute drive (but after about 10-12 minutes of idling this morning in the garage), I get 72*C on the engine temp (per display 06) and only about 29-30*C on the core (display 03). Taking your advice, I called up my engine builder (who I buy lots of parts from as they get jobber pricing) and ordered the only remaining heater control valve / duovalve in town. Actually, in the country, as the parts supplier (altrom.com) deals across the country. I can return it if I need to. I will do a longer drive tonight when I'm out and about, and will run the diagnostics again.
Mucking around with the duovalve before (the disassembly and cleaning, per your site), it looks like a pretty simple R&R? One hose on the front side, a couple on the back/bottom side. There's room to clamp the hoses, I think, and then just release the hose clamps to get it out?
When I did the thermostat on Sunday evening, I was *****ing and cursing about how difficult it was to access it. On my Saabs and my Volvo, I could have it done in about 2 minutes. I took me about 2 hours on the AMG, fiddling with torx sockets and a variety of extensions and ratchets. But on my Saab, the heater valve would involve contortions underneath the dash...
Oh, and I did try blocking the rad too. I had some leftover plastic sheet and I blocked out half the rad. Didn't help that much. It's currently -25*C and I wished my parents had immigrated to California instead. Every winter when it gets cold I threaten to move to the Bahamas. Can never follow through though....
12-08-2009, 03:21 PM
#4
MBWorld Fanatic!
Thread Starter
Drove it some more at lunchtime, this time a good 20 minutes. Engine fully warmed up to 80-81*C, but the highest the heater core temp went up to was 49*C. Perhaps I will try and disassemble and clean the duovalve again before installing the new one I just picked up.
