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Discussion Starter · #1 ·
HEllo, I have strange problem. My car only blowing cold air under the car. All coolant level are ok and there is no visual leak..

But the car have only cold air and my automatic heater are under "Hi" mode.

No fault code. Anyone know this problem ?

Regards
 

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sounds like the servo that controls the heater flap in the heater box within the dash could of failed, or the heater control its self ..
ie link below link for a idea
the heater matrix on these cars is always hot and the heater box just controls the air flow through , would check the matrix is hot when car been run for a good hour first ,
 

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Discussion Starter · #3 ·
HEllo, when I touch the plastic cover at the level of pedal where the heater matrix is located I can feel the heat...
 

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HEllo, when I touch the plastic cover at the level of pedal where the heater matrix is located I can feel the heat...
then its a air flap fault on heater box ,, or the heat switch on heater controls , what year is the car and what spec
 

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just had a look for fuse diagram on it cant find a fuse ,, it most likely the switch or that servo motor on the heater box behind the dash , i would strip the switches out first check the switch for heat up and down and use a meter on resistance work switch while looking for a change on the meter ,, i would also use a probe from battery to the motor on the servo see if it moves with power to it,
something like below link,,
 

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Discussion Starter · #7 ·
HEllo, I go back to us. After 1 hours of driving I can feel the hot air coming... Its really long for start to have hot air on this car... ?
 

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Discussion Starter · #8 ·
HEllo,

today I checked about 2 heater hose. First at the top its really hot and second its hot. I always have cold air even in "HI" mode...
 

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HEllo,

today I checked about 2 heater hose. First at the top its really hot and second its hot. I always have cold air even in "HI" mode...
My heater on my R56 Cooper was not working very well, just blowing lukewarm air, and it was getting uncomfortable at -2C in Scotland so today I tried a few things. First I drove around with the coolant temperature displayed via the hidden menu (see this video for how to display:
) and established that the coolant was heating up to a suitable temperature on the road (up to around 103C and steady at 70mph), so I concluded the thermostat was probably not the problem. Then with the car still hot I tried flipping the temperature on the heater between highest and lowest a few times (wait 10 seconds each time to let servo do it’s thing) to see what difference in temperature I could feel at the vents: this seemed to help a bit, or maybe I was imagining it. I also tried opening the bleed screw, with engine hot and running, but no air came out, only coolant. Then I added some radiator flush from Halfords and drove another 20 miles (plus turned temperature up and down again), during which there was a significant improvement, nice hot air coming out of the vents and car got warm enough to have to turn the heater down a bit. Tomorrow I will drain and refill with fresh coolant, which I had been intending to do in any case.

Anyway my theories for a cold or insufficiently warm heater are:

1. Air lock in heater matrix, caused by
a) inadequate bleeding at coolant change or after running too low coolant level. Solution: bleed coolant system correctly using bleed valve. (Not sure if necessary to do with coolant hot, heater set to hot and heater fan on?)

Or b) leak allowing air to be drawn in. Solution: find and cure leak, then bleed as above.

2. Switch or servo control defective: check if you can hear it switching, I could on mine, plus there was a small but definite difference in temperature between hottest and coldest settings. Solution: try flipping between hottest and coldest setting, pausing for 10 seconds a few times to see if anything can unstick itself, but if not repair/replace faulty item.

3. Clogged heater matrix. Solution: try flushing system with suitable radiator flush, probably worth doing at least a couple of times as the next step if that fails is a new matrix (but maybe bear in mind possible cause 4 below).

4. I have heard it could possibly be a sign of a failing head gasket, I would guess either oil in water produces sludgy goo that clogs everything up, or combustion gases in coolant leading to air lock in matrix??

If any of the above is codswallop please do say so!

EDIT: I forgot the possibility of a dodgy thermostat in that list of causes, can be eliminated by observing the coolant temperature on a run via hidden menu as per video above.
 

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Update: the somewhat mediocre improvement was all too brief and the heater output soon went to lukewarm at best with constant screen misting problems and having to dress like an Eskimo on longer journeys, so after a run I felt the heater pipes where they go through the bulkhead and determined that one was v hot and the other was just moderately warm.

Diagnosis now almost certainly a clogged heater matrix so I removed the matrix and tried back flushing it, which revealed some small lumps of limescale. The car came from the London area where I know the tap water is very hard, so I concluded the matrix was probably clogged up with limescale due to tap water being used in the cooling system.

I filled the matrix with pure white vinegar and soaked it a couple of hours, then I back flushed it with full force mains water and several large chunks of limescale came out plus lots more smaller bits. I soaked it again overnight but not very much more stuff came out (though some may have been dissolved by the vinegar).

Today with the matrix reinstalled and system bled it is pumping out tons of lovely heat and both pipes through the bulkhead are scorching hot.
 

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Discussion Starter · #11 ·
So its same like me ? My top hose to the heater matrix is HOT and second hose bottom is cold.. So your fix is to change the radiator?

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So its same like me ? My top hose to the heater matrix is HOT and second hose bottom is cold.. So your fix is to change the radiator?

Regards
First take the matrix out and check if it is blocked. If it is you may be able to unblock it by the same method I used but if not then yes, fit a new one.
 

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Discussion Starter · #13 ·
ok crazy... Because garage told me its 100% thermostat housing the problem don't open for have heater.. I told him its impossible if I have top hose heater very hot and not the second (cold)...
 

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thermostat housing has a bypass for the heater, it's why they normally blow warm quickly, even with coolant temp in the 60's
 

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most common is is the rad cap that wont let system pressurise to around 2bar what happens it lets the air in header tank move to the engine and end up in the matrix hence cold heater , ie back pressuring , I had one do this yesterday again spat coolant out the header tank cap , fitted new cap and it drove 300 miles home no issues with coolant after
 

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thermostat housing has a bypass for the heater, it's why they normally blow warm quickly, even with coolant temp in the 60's
Yes I was monitoring coolant temperature via the hidden display yesterday and heat was already coming through the vents when the temperature was in the 50s.
 

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most common is is the rad cap that wont let system pressurise to around 2bar what happens it lets the air in header tank move to the engine and end up in the matrix hence cold heater , ie back pressuring , I had one do this yesterday again spat coolant out the header tank cap , fitted new cap and it drove 300 miles home no issues with coolant after
But OP says no leaks and fluid level ok, so I doubt that is the problem in his case.
 

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ok crazy... Because garage told me its 100% thermostat housing the problem don't open for have heater.. I told him its impossible if I have top hose heater very hot and not the second (cold)...
How long does it take for the big top hose going forward to the main radiator in front of the engine to get hot? It should be very hot within ten minutes of starting driving.

If it doesn’t get hot for a long time and never gets very hot then the thermostat is not closing when it should (when coolant is cold), but if it does get very hot quickly and so does one hose to the heater matrix then the matrix is definitely blocked.
 

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thermo housing is piloted ecu controlled, engines takes well over a hour at 2000 revs faster if under load, they are also thermal positive ie bottom hose stays cold for a lot longer than any other car ,, also they run the rad hot water in the top and push the heat down wards,, thermo housing dont open until gets to 104c and above as the running temps is 104c , i work on these things non stop and this is how they work,, DO NOT HEAT UP IN TEN MINUTES UNLESS REVING FLAT OUT MAYBE ,
as for rad cap they dont loose coolant all the time they just back pressure the air gap in the header tank and send it to top of head where it turns in to steam and sends that to matrix, or if cap is total ruined will blow the coolant out via its pressure relief valve ,,
 

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thermo housing is piloted ecu controlled, engines takes well over a hour at 2000 revs faster if under load, they are also thermal positive ie bottom hose stays cold for a lot longer than any other car ,, also they run the rad hot water in the top and push the heat down wards,, thermo housing dont open until gets to 104c and above as the running temps is 104c , i work on these things non stop and this is how they work,, DO NOT HEAT UP IN TEN MINUTES UNLESS REVING FLAT OUT MAYBE ,
as for rad cap they dont loose coolant all the time they just back pressure the air gap in the header tank and send it to top of head where it turns in to steam and sends that to matrix, or if cap is total ruined will blow the coolant out via its pressure relief valve ,,
With respect I don’t agree with a lot of what you have written, so I will respond to each point in turn with my view:

Firstly I don’t know how long it takes a Mini to get to operating temperature at 2000 rpm without load, but that is purely academic as the car is designed to be driven, i.e. operated under load. I do know that if started cold and left to idle it will only get to around 50c in 10 minutes, but if driven on the open road at up to 60-70mph without excessive revs it will reach around 103C in around 10 minutes. My car is a non turbo Cooper BTW, however ANY CAR THAT TAKES AN HOUR OR MORE TO REACH OPERATING TEMPERATURE IN NORMAL DRIVING HAS A MALFUNCTIONING COOLING SYSTEM, normally caused by a thermostat that is open at cold or opens well below operating temperature.

The job of the thermostat is to stay closed to stop coolant circulating through the radiator while below operating temperature (most efficient temperature), so that the engine heats up ASAP, then to open to allow coolant to circulate through the radiator and cool down when it goes over operating temperature. It will then close again once temp drops to a certain point, and so on. All thermostatically controlled internal combustion engine cooling systems work this way, regardless of whether the thermostat is controlled by an ecu or it is an old fashioned mechanical one.

I don’t know what you mean by “thermal positive” but the radiator’s job is the same on all cars and yes, the top hose is usually the one bringing hot coolant from the engine to the radiator and the bottom one takes cooled coolant back to the engine. If the coolant leaving the radiator at the bottom is not cool then obviously the radiator (or fan) is not doing it’s job and the engine could overheat. I don’t know that the Mini radiator and fan combination is particularly efficient but I seriously doubt it is the case that the “bottom hose stays cold longer than any other car”.

The expansion tank cap does not force anything anywhere, if it is working correctly the release valve in it stays shut until the desired pressure has built up, then it releases excess pressure by venting off the header tank air. The pressure is caused by heating the closed system of the coolant circuit. If functioning correctly air in the top of the header tank will be slightly compressed by the expanding coolant, meaning that the coolant level will rise slightly, which is why it should only be checked when cold. No air will ever get from the expansion tank to anywhere else in the system if the cap is functioning properly and the cold coolant level is correct.

If the expansion tank cap is not working correctly it allows the air to vent at too low pressure, then the coolant will boil over once warmed up forcing air then fluid/steam through the cap. This is because the boiling point of the coolant is lower at the lower pressure, i.e. the boiling point is below the thermostat controlled operating temperature.

This boiling will produce steam inside the engine and heater matrix as well, but that will condense back to a liquid once cool again, however if a lot of the coolant has been lost through boiling over through the expansion tank cap then air will be drawn into the system as it cools again. This can be rectified by refilling and bleeding the coolant system using the bleed screw on top of the thermostat housing with engine cold and idling, plus a replacement expansion tank cap of course.

However to sum up for the OP if your car‘s radiator top hose heats up quickly, your coolant level is correct and does not need topping up frequently and only one of the two heater matrix hoses gets hot, then I am certain you have a blocked heater matrix.
 
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