Hot air blowing constantly
Discussion
Second post today - been busy again.
The two black swivel vents along the tunnel just below the dash trim are constantly blowing hot air. I can turn the hot on and add more if I want. However, not good when it is 30+ outside. I cannot seem to turn this hot air supply off. Closing the vents stops a direct flow but as it is always blowing invariably some still comes out - how can I turn this hot air off?
Thanks.
The two black swivel vents along the tunnel just below the dash trim are constantly blowing hot air. I can turn the hot on and add more if I want. However, not good when it is 30+ outside. I cannot seem to turn this hot air supply off. Closing the vents stops a direct flow but as it is always blowing invariably some still comes out - how can I turn this hot air off?
Thanks.
Starting with the obvious question: Do you have Aircon fitted?
Assuming you do, turn it on and be sure that the temperature dial is at least changing the air temperature on a vent, any vent, to eliminate a dodgy connection at the back of the dial as a cause of the problem.
Those vents are nearest to the heat trap created by bodyshell at the back of the engine so this air will always be naturally a smidge hotter when the car is running hot. It might be worth looking at the state of your heat shielding if the transmission tunnel itself also feels more warm than it used to by your feet.
Also, if I remember correctly from my dash strip out, these vents have the shortest hose runs from the heater matrix, so when heat is required these will always be the hottest.
Since shutting the vents off is not seeming to be sufficient, take a look at this thread:
https://www.pistonheads.com/gassing/topic.asp?t=87...
Maybe UKKID35 can explain his expansion tank mod.
And if you're really stuck but don't fancy doing any mods, a tennis ball fits nicely in the end of the pipe, held in place with some gaffer tape.
Assuming you do, turn it on and be sure that the temperature dial is at least changing the air temperature on a vent, any vent, to eliminate a dodgy connection at the back of the dial as a cause of the problem.
Those vents are nearest to the heat trap created by bodyshell at the back of the engine so this air will always be naturally a smidge hotter when the car is running hot. It might be worth looking at the state of your heat shielding if the transmission tunnel itself also feels more warm than it used to by your feet.
Also, if I remember correctly from my dash strip out, these vents have the shortest hose runs from the heater matrix, so when heat is required these will always be the hottest.
Since shutting the vents off is not seeming to be sufficient, take a look at this thread:
https://www.pistonheads.com/gassing/topic.asp?t=87...
Maybe UKKID35 can explain his expansion tank mod.
And if you're really stuck but don't fancy doing any mods, a tennis ball fits nicely in the end of the pipe, held in place with some gaffer tape.
There are several variants of heater plumbing fittied to Cerbs, seemingly dependant on when they were produced, the day of the week, and whatever was in the parts bin at the time. Early Cerbs had a solenoid operated valve in the hot air pipe connecting the heater box to the mixing plenum behind the centre dash so when the hot fan was off no hot air could be forced in by ram effect from the front N/S wing. In later cars this was removed, god knows why.
There was a mod for those cars which involved sealing up the inside wing to prevent ram air going through the heater matrix, and then cutting a hole in the removal panel in the passenger footwell used to access the heater box to turn the heater into a recirculating system.
To add to that some cars seem to be plumbed differently with hot air only available from some vents and cold only from some others. Other cars, like my '96, have hot & cold available from all vents.
There was a mod for those cars which involved sealing up the inside wing to prevent ram air going through the heater matrix, and then cutting a hole in the removal panel in the passenger footwell used to access the heater box to turn the heater into a recirculating system.
To add to that some cars seem to be plumbed differently with hot air only available from some vents and cold only from some others. Other cars, like my '96, have hot & cold available from all vents.
NuddyRap said:
Since shutting the vents off is not seeming to be sufficient, take a look at this thread:
https://www.pistonheads.com/gassing/topic.asp?t=87...
Maybe UKKID35 can explain his expansion tank mod.
Sadly never got around to attempting to fit the electric valve, and have employed this much cruder option instead.https://www.pistonheads.com/gassing/topic.asp?t=87...
Maybe UKKID35 can explain his expansion tank mod.
The valve should allow the heater matrix coolant flow to be diverted, reducing the chance of hot air escaping even with the vents closed (or plugged)
This suggests I may have been lucky not to fit the cheap pattern valve that I bought anyway
https://www.youtube.com/watch?v=zyl5cCOvIis
Thanks for the quick replies.
The vents I’m referring to are not the ball vents which do blow colder air (usually from outside) but the two on the transmission wall on the inside of the footwell.
My air con has been removed
My trans tunnel does get pretty hot and the heat does come up through the gear knob area but I can live with that. It is the pretty big flow of hot air through the vents mentioned that I’m peeved with.
I cannot believe that these vents should be blowing hot air constantly - I’m not 100% sure but I don’t think they were on all of the time when I originally got the car nearly two years ago!
The vents I’m referring to are not the ball vents which do blow colder air (usually from outside) but the two on the transmission wall on the inside of the footwell.
My air con has been removed
My trans tunnel does get pretty hot and the heat does come up through the gear knob area but I can live with that. It is the pretty big flow of hot air through the vents mentioned that I’m peeved with.
I cannot believe that these vents should be blowing hot air constantly - I’m not 100% sure but I don’t think they were on all of the time when I originally got the car nearly two years ago!
Seems there might be an inconvenient difference between our cars in this instance, as my transmission tunnel vents are also the ball type with the same diameter of donkey d
ck carrying the air to my feet as to the dash vents. It's exactly the same setup for me, so pulling the vent off and shoving a tennis ball in there would temporarily solve the problem you describe, if I had it.
In that case all I can recommend is mods in line with some of the previous posts as a permanent fix, or blocking it up in some other way temporarily.
ck carrying the air to my feet as to the dash vents. It's exactly the same setup for me, so pulling the vent off and shoving a tennis ball in there would temporarily solve the problem you describe, if I had it. In that case all I can recommend is mods in line with some of the previous posts as a permanent fix, or blocking it up in some other way temporarily.
Haha - I laughed twice as I meant 37 outside (temp) and at the drawing with a mates name!
I literally “would if I could but I can’t” —- the said hole for the ram air I don’t think exists on my car yet it is right that the hot air only comes in whilst moving. My heater also works independantly of this extra hot air.
The hole in the front below the passengers indicator goes through to a large aperture with an air con part located there. I have previously accessed this from the wheel arch and don’t remember any large piping big enough to squeeze a a tennis ball through.
I literally “would if I could but I can’t” —- the said hole for the ram air I don’t think exists on my car yet it is right that the hot air only comes in whilst moving. My heater also works independantly of this extra hot air.
The hole in the front below the passengers indicator goes through to a large aperture with an air con part located there. I have previously accessed this from the wheel arch and don’t remember any large piping big enough to squeeze a a tennis ball through.
so did anyone fit the ford puma heater control valve
https://www.ebay.co.uk/itm/Heater-Control-Valve-Fo...
https://www.ebay.co.uk/itm/Heater-Control-Valve-Fo...
Byker28i said:
Wolvesboy said:
My trans tunnel does get pretty hot and the heat does come up through the gear knob area but I can live with that. It is the pretty big flow of hot air through the vents mentioned that I’m peeved with.
This is why my car is decattedWolvesboy said:
Decatted so nothing underneath the gear box except plan old exhaust until the smallish back boxes!
Wrapping the exhaust manifolds / headers make a big difference to that too as does adding more heat shielding 
That's not the best pic, but you can see half of the extra shield I added there. I riveted it to the gearbox mounts sheilds (bent bits of aluminium). I kind of miss the heat from the tunnel in winter now!
Hopefully you will find why you have hot air blowing it does sound like yours is a bit different....
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