No Hot Air in Heaters

[roryhopcraft123]

Hi All,

Sorry, i know that this might be a little bit of a repeat from other discussions but they all seem to have slightly different issues than mine.

I recently bought my Bongo (BamVan) a month ago and have done a couple of trips over the bank holidays. I have just come back from a 400mile round trip and noticed that my front heaters only blows warm air, not enough to demist the screen. When we bought BamVan we checked that the heaters worked and they did (got a lot hotter than they are now). So scanned through the forum looking for answers. After investigating the rear heater does NOT blow hot air either. This is for a 2.5 diesel auto (N reg) with manual heater controls)

So below is what i have found:

1) The linkages in the passenger's footwell are all ok and moving
2) front and rear heaters blow cold air on cold and warm air on hot (just not hot hot)
3) Temperature gauge creeps up after 20mins to the 11 o'clock position and stays there (didnt overheat after 200 miles)
4) Coolant level is constant - so no leaks etc
5) both the pipes from the front heater matrix are hot (one slightly warmer than the other)
6) fuses are all ok

Im now at a complete loss on what to do next...

The forums suggest checking/changing the thermostat... is there a way to check if it is working correctly before i change it? If i do need to change it do i have to do a full bleed?

Im based in Kent (UK), is there any known specialists around the area that might be of use?

Thanks

[g8dhe]

If it takes 20 minutes to warm up then that would suggest either a faulty thermostat or even no thermostat at all!
However if the pipes to the heating matrices are hot one side and cooler on the other then it might also be blocked matrices as well as thermostat problems. This suggests poor maintenance in the past with reduced flow thru them and hence the poor heat output. A complete flush and overhaul of the cooling system might be in order looking for crunchy hoses and rusted pipes and flushing radiator and heating matrices to remove debris in them.
Its not easy to check the thermostat without removing it, unless you have an IR thermometer to measure the temperatures around the system, flushing the system or removing the the thermostat will require a full bleed of the system of course.

[mikeonb4c]

If it takes 20 minutes to warm up then that would suggest either a faulty thermostat or even no thermostat at all!
However if the pipes to the heating matrices are hot one side and cooler on the other then it might also be blocked matrices as well as thermostat problems. This suggests poor maintenance in the past with reduced flow thru them and hence the poor heat output. A complete flush and overhaul of the cooling system might be in order looking for crunchy hoses and rusted pipes and flushing radiator and heating matrices to remove debris in them.
Its not easy to check the thermostat without removing it, unless you have an IR thermometer to measure the temperatures around the system, flushing the system or removing the the thermostat will require a full bleed of the system of course.

Spot on Geoff - saved me a lot of typing.

And welcome roryhopcraft

[roryhopcraft123]

Hi
Thanks for the quick response!
When you say flush you mean pipes off rad/matrix/rear matrix and blast hose through?
Thanks!

[g8dhe]

Yes that is the most effective route, BUT be aware the heater matrices and various other parts have plastic spigots which are fragile with age, so take great care when removing hoses from them as otherwise you will be replacing the whole item!

[mikeonb4c]

Yes that is the most effective route, BUT be aware the heater matrices and various other parts have plastic spigots which are fragile with age, so take great care when removing hoses from them as otherwise you will be replacing the whole item!

Also, i'm never convinced that flushing can magically make a scaled up rad matrix free flowing. The main rad on Bongos often starts to fail/leak at the plastic top/main metal body interface anyway with age and replacement is not that expensive. So if in doubt i'd fit new main rad and thermostat anyway. Heater rad is trickier but can still be done. Rear rad i suspect could be trickier still but could always be taken out of circuit. Feel top hose for crunchiness - if it is the rads are likely scaled up also.

[g8dhe]

Wouldn't disagree with that Mike, and given that the radiators tend to fail at around 20+ years it could pay not to have the frustration of seeing the top of the radiator leaking, so well worth replacing especially if you do it yourself as the cost is only in the order of £100 to replace with new.

[cwilliams255]

While not specific to this issue or this thread exactly, I recently took the rear heater out of my loop and the bongo seems happier. It didn’t have a cooling problem before, main radiator replaced a couple of years back, hoses changed etc. I did buy a new front matrix just before and had planned to do at the same time for good measure but having seen the pain endured by some to get the matrix out and time contraints I had, I decided against for now. Having said that on mine 18 = cold, 28 = hot anything else vague inbetweeness so maybe it does need doing

Anyway back to thread, get vehicle to temp, set heaters to hot and cold and grab some hoses and see what’s happening. There is a good diagram of the cooling loop somewhere so should be reasonably easy to work out the problem. It does seem odd that you see same prob front and rear, if rear isn’t essential I’d blank off, drain bleed and see how front is going, replace front if necessary