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Discussion Starter #1 (Edited)
Hi guys, need some help, my 2002 cooper s (non climate control) has a problem with the heaters, they only blow lukewarm air, this is what i have done so far,

New thermostat, flushed system
Bled the system, everything is circulating
rad hot, all pipes hot & heater matrix also hot
Temp sits half way, no over heating
no oil in water, no water in oil, no smoking
heater knob cable attached both ends and when i turn it to cold it goes cold but when i turn it to hot i get lukewarm at best

I'm really stumped as the matrix is Boiling hot as in too hot to touch but still no heat.
Any ideas before i burn it !!! Lol.
 

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Modern cars are very difficult to bleed the coolant system due to the cluttered engine bay and tight angled pipe work, did you use the bleed valves fitted and did you bleed it when the heaters where on hot but blowers off. As this is either air in the matrix or the heater valve which controls the flow of water through it isnt openning fully due to say a cable clip come off. Make sure its the inner cable moving not the outer casing on the heater cables, if its easy, remove the cable and move the valve by hand if possible or visually see that its travelling to both stops, hot and cold. The matrix may feel hot but the blower will cool this down rapidly if there is a restriction or air in it. I bet if you put your hand on it when the blowers are on you will feel it cool down. My bet is on air in the system. Just as a quick check, remove the coolant filler cap and rev the engine @ 1500 rpm and see if the heaters get hotter as this should shift some air out, remember that you will hold the revs untill thermostat opens at least.
 

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If you are really convinced their is no air lock in the system and have carried out all the checks as advised by Stead34..........the only other possibilty I can think off is perhaps one or other of the air blending flaps within the heater unit are not responding to the RH rotary control which directs and blends the hot/cold air to the various outlets. These can jam shut, not fully open or the plastic linkage mechanisms seize/break or the cable behind the control panel knob (drivers side) can also become dislodged meaning the hot air is not being directed/blended to the outlet vents.

Can you get any hot air out the dash eyeball vents or windscreen demister vents?

Mini One Heater Problem -
Quote:
"I found the problem to be that the linkage for the heater control below the consol on the drivers side was disconnected. The linkage had obviously been knocked and had jumped out of its socket. The location of the linkage is below the drivers left leg.
Once I re-located the linkage the heater worked fine."
http://www.mini2.com/forum/first-generation-mini-one/152785-mini-one-heater-problem.html

RealOEM.com BMW R50 Cooper Various Bowden cables / shafts
 

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Yes, sorry if ive given wrong info on the way the heater control the temps, it is either done by a valve or flaps,flaps in this case but the checks will be the same though what ever is fitted, you just need to make sure that whatever the cable operates functions correctly..
 

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Discussion Starter #5
Thanks for the reply's.
I'm a mechanic, and im pretty sure there's no air left in the system as everything is perfect, the heaters do not get any hotter when the revs are held up and yes its been bled with it set to hot and blower off. Also the matrix does not get cooler when the blowers are flat out it is still too hot to touch, also i have noticed if i leave it idle with the heater set to cold and the blowers off for 5 mins then turn it back to hot and put the blowers on it is hot but within a minute its back to cool/lukewarm and thats how it stays again.
 

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If your sure the heater matrix is hot and circulating, then you need to check the heater box and its controls, as said if possible try and see the cables operating the flap and turn it manually if possible and hold it directing to hot, if its not the controls then the airbox may need to be removed for inspection..
 

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Photo below of non-climate MINI heater/ac unit out the car, note the silver metal horizontal shaft which controls the flaps via the flexible shaft from RH control panel knob, most of the flap actuating levers, etc are external to unit visible behind the dash/console and can be checked for movement.




The auto climate type of Mini heater unit below uses 3 small servo motors to control the flaps instead but manual levers, etc are very similar and clearer to see in this view:



http://www.realoem.com/bmw/showparts.do?model=RC32&mospid=48010&btnr=64_1148&hg=64&fg=45
 

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Discussion Starter #9
Today i have,
first bled it again - no air.
re-checked matrix - so hot i can not keep my hand on it.
checked control cables, disconnected from heater box and operated arm manually from hot to cold and seems to be working(can hear flaps changing positions) and when it is on cold it blows cold but when on hot it blows lukewarm only.
If i turn the heaters to cold for 5 mins then back to hot and speed 1 i get hot air for about a minute before going cool, but if i put the blower flat out it goes cool instantly.
Really getting on my nerves now, i just don't understand, if the matrix is giving out adequate heat and the cables and flaps are operating correctly then where's my heat!!!!!!!!!
Also it's the same from all the vents upper, mid and lower.
 

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Hi ya

I have had something like this on another car and it turned out to be the pollen filter.
When I got it out I had never seen one in such bad state before. If you have one fitted remove it and see what happens
Just a surgeston as your previous posts says matrix is getting hot and vent flaps are working and the fan is working. Just a thought if it can't draw any air though the matrix = no hot air out.
Anyway hope it helps :)
 

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If i turn the heaters to cold for 5 mins then back to hot and speed 1 i get hot air for about a minute before going cool, but if i put the blower flat out it goes cool instantly.
Running out of ideas now! :confused:

Does the fan boosted air flow have the same force whether blowing hot, cold or lukewarm?
I am just wondering if a flap/damper which blends hot and cold air has broken and is 'waving about in the breeze'........then when you boost the fan airflow perhaps it flips back into the position which cuts off all heat to the vents?

More info in links below which may be of help.........

There is a diagram in this NAM link below of the internal flaps/dampers and linkages, it is a climate unit but is very similar to the standard manual Mini heater apart from using servo control motors instead of bowden cables/rotary knobs to operate the linkage arms:
North American Motoring - View Single Post - Heater issues

This old Mini2 post below shows a photo of a broken plastic heater flap/damper:
Quote, "My problem was a broken cam follower arm on the heater air flow control damper"
http://www.mini2.com/forum/first-generation-faults-fixes/150313-vent-feet-not-working.html#post3271704
 

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Discussion Starter #12
Marque Thanks for the input, just whipped the pollen filter out didn't think to check that, it was caked but unfortunately still the same :(

Mab01uk, yes air flow is the same weather hot or lukewarm, but i have just noticed that the passenger dash vent is blowing slightly warmer than all the rest.
So i am starting to think that the problem is possibly inside the heater box and requiring a full strip down to find it what you think?
 

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Operating the recirc will eliminate the pollen filter, strange its warm for a minute then cools down if going from hot to cold, you would put your money on the matrix cooling down, if you can get your hand on the matrix when the blower is on can you feel the forced air coming through being alot hotter than is getting to the vents, if this is the case you may have to take the dash out to investigate as you know the hot air is being produced but not getting to the vents...
 

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Could there be something restricting the flow through the matrix? It would still be hot to the touch and the heat would last as long as the blower took to cool it down as it is in limited supply.
Just a thought.
 

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Mab01uk, yes air flow is the same weather hot or lukewarm, but i have just noticed that the passenger dash vent is blowing slightly warmer than all the rest.
So i am starting to think that the problem is possibly inside the heater box and requiring a full strip down to find it what you think?
Would be nice to be really sure of problem source first......as quite a big strip down job (even for you as a mechanic!) as you can see from pictures in this post:
http://www.mini2.com/forum/first-generation-faults-fixes/150313-vent-feet-not-working.html#post3271704
....although dash can be taken out as complete assembly in one piece complete with steering wheel, wiring harness, etc.
(Looks easy on the factory production line at Oxford when I have seen them put in but dash assy goes in on a special lifting jig and then gets secured by the line workers with just 2 bolts each side!)

I would maybe be tempted first to try to locate a cheapish s/h Mini heater unit from a scrap yard to examine it more closely out of car for the potential fault areas.......would also be a source for spares if the problem does indeed look to be inside heater box?
 

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Had a similar problem, ended up being both a lack of coolant, had to be perfect and air in the system, it was bled 7 or 8 times to get it right. That was after a new thermostat.

Dunno if this helps, but the system is a bugger to get right.

With the coolant, filled up, car burped, not enough coolant sort of thing....
 

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Discussion Starter #17
Would be nice to be really sure of problem source first......as quite a big strip down job
Yes i know what you mean, although it's looking like the way forward there's just something niggling at me.
Tomorrow i am going to run the car up to temp then run the heater until it goes cool then check the return pipe directly at exit from the matrix, thinking it will cool significantly maybe and if so pointing to a restriction or possibly a water pump not pumping efficiently enough to supply a steady feed to the matrix.
I don't know just trying to think out of the box now. lol
 

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Discussion Starter #18
if you can get your hand on the matrix when the blower is on can you feel the forced air coming through being alot hotter than is getting to the vents
No unfortunately i cant feel the core of the matrix while it is in place, so i will carry out the procedure as mentioned in my above post and see what happens.:nice:
 

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Yes i know what you mean, although it's looking like the way forward there's just something niggling at me.
Tomorrow i am going to run the car up to temp then run the heater until it goes cool then check the return pipe directly at exit from the matrix, thinking it will cool significantly maybe and if so pointing to a restriction or possibly a water pump not pumping efficiently enough to supply a steady feed to the matrix.
I don't know just trying to think out of the box now. lol
Good idea! :)
This would at least confirm whether or not the coolant system/heater matrix is providing a constant source of heat and that the problem of delivering the heat to the vents maybe lies elsewhere........
 

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Im confused, i thought you could get your hand on the matrix, as you said it was to hot to touch, this would have to have been direct of the front or back as the sides wouldnt be a conclusive test. The return pipe is a good way of telling but the accuracy will depend on how long the pipe is, as the heat will travel but doesnt disperse that quick from the rubber. How many bleed nipples did you use when bleeding the system, there is normally one specifically to aid bleeding the matrix. If your a mechanic have you got the means of filling the system under pressure(hose attachment) or an extension bottle to raise the height of the water level. Im sure if your water pump wasnt circulating the water you would have more to worry about than cold blowers.
 
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