Heater problem

bongobeliever · Post by **bongobeliever** » Fri Dec 11, 2015 12:14 pm

Dear Bongo chums, I'm relying on you for advice on my heater problem!
The heater works only when it's set to the maximum 32 degrees. Even half a degree less means all I get is cold air. My excellent local garage chappy has tried all the simple things – airlock, thermostat, clogged-up cabin air temperature sensor – and is flummoxed.
It's interesting to see that unless the air is directed to the footwell, instead of moving incrementally as the heater is turned down, the rod to the right of the passenger footwell shifts a good inch when the setting is reduced by just half a degree from 32.
It then doesn't move again until I turn the setting down to 24 degrees, whereupon it starts moving incrementally (almost imperceptibly) as presumably it should. But even at 24 degrees, I note, the air is pretty cold.
If the air is directed to the footwell, the rod works incrementally – but the air is still cold except on the max setting.
My mechanic reckons the only thing left is a faulty heater matrix, but has asked for your advice before he commits himself.
What do you reckon?
I want to go off a-Bongoing again but I don't fancy it without some warmth!

cmm303 · Post by **cmm303** » Fri Dec 11, 2015 2:46 pm

Doubt it is the heater matrix as it works on max. When set to the maximum temp it ignores the input from the cabin temp sensor and goes full heat. On minimum temp it goes max cold. Anywhere in between it adjusts between hot and cold based on cabin sensor feed, which is where it sounds like the problem is.

bongobeliever · Post by **bongobeliever** » Fri Dec 11, 2015 4:30 pm

Thanks. It seems it's a common problem. Since mentioning it on the Bongo Facebook page this morning I've had six messages from people saying they're suffering the same thing - and, worryingly, none has got it sorted yet!

mikeonb4c · Post by **mikeonb4c** » Fri Dec 11, 2015 5:49 pm

bongobeliever wrote:Thanks. It seems it's a common problem. Since mentioning it on the Bongo Facebook page this morning I've had six messages from people saying they're suffering the same thing - and, worryingly, none has got it sorted yet!

If push comes to shove, can a manual way of adjusting the heater be rigged up as a 'get you by' solution?

I'm feeling smug as I have the manual aircon system, with me as the temp sensor

cmm303 · Post by **cmm303** » Fri Dec 11, 2015 6:49 pm

bongobeliever wrote:Thanks. It seems it's a common problem. Since mentioning it on the Bongo Facebook page this morning I've had six messages from people saying they're suffering the same thing - and, worryingly, none has got it sorted yet!

This thread makes good reading - its quite long! http://www.igmaynard.co.uk/bongo/forum/ ... 3&p=669147Unfortunately it does not give a solution

. I thought I had seen resistance values for the thermistor that measures the cabin temperature quoted but can't find it - that would enable it to be identified as the culprit or eliminated. It's where I would start.

psquiddy · Post by **psquiddy** » Sat Dec 12, 2015 12:54 am

This thread makes good reading - its quite long! http://www.igmaynard.co.uk/bongo/forum/ ... ortunately it does not give a solution

That link doesn't work for me - it sends me to post a reply instead.

cmm303 · Post by **cmm303** » Sat Dec 12, 2015 10:01 am

psquiddy wrote:
This thread makes good reading - its quite long! http://www.igmaynard.co.uk/bongo/forum/ ... ortunately it does not give a solution
That link doesn't work for me - it sends me to post a reply instead.

Oops. My bad. http://www.igmaynard.co.uk/bongo/forum/ ... r&start=30

jimmo62 · Post by **jimmo62** » Sat Dec 12, 2015 12:46 pm

I think there may be good news and bad news here - the good news is that it may be working as designed, the bad news is that "as designed" may not be what you want..... As I understand it from a careful read of the handbook and backed up by experiments in a 1995 2.5 diesel, the system seems to work like this -

There are 2 modes - Auto and Manual. Auto is activated by pushing the Auto button and controls the fan speed and temperature of the air outlets to maintain the overall cabin temp. In mine, it switches the outlets to feed and screen. If you now press any of the controls (except the temp up/down control) the system drops back to Manual. You can now control the fan speed and temp manually but critically, the dash vents if turned on ALWAYS blow air at outside temp. So you can have toasty feet and cool air in your face.

I have not found a way on Auto to get the dash vents to blow hot.

Hope that helps and if anyone has managed to get theirs to work differently I'd love to hear!

Post by **g8dhe** » Sat Dec 12, 2015 12:51 pm

I've also found that the two extreme temp. settings are "special" in that rather than trying to achieve the target temperature setting, the controls are set for Maximum fan speed and Max/Min temperature settings to allow you to quickly purge the air in the cabin.

BongoKiwi · Post by **BongoKiwi** » Sun Dec 13, 2015 11:40 am

I think jimmo62 is right about the aircon algorithm.

I've an '09 Mazda 6 and its aircon works in the same way.

It will only blow hot air to the footwells when it's warming the cabin up and will only blow cold air out the top vents when it's cooling down on Auto.

I guess it's a Mazda thing!

corrour · Post by **corrour** » Mon Feb 29, 2016 8:31 pm

Things look like this topic will last a while
Trying all combinations at the minute to report findings.

corrour · Post by **corrour** » Mon Mar 07, 2016 7:41 pm

One thing you could do is disconnect the control rod from the servo to the heater flap in the passenger footwell and wedge it in the hot position as a temporary fix.
It would give you hot air but still give you full control of direction.
Connecting it back up when weather gets warmer and you need Aircon

tommyrugrat40 · Post by **tommyrugrat40** » Fri Mar 11, 2016 3:07 pm

Hi Folks

I also posted this problem on the Facebook back in February and had lots and lots of people get in touch privately stating that they had the very same issue, (hot at 32 degrees, cold at any other temperature) I personally have been through the entire heating system to try and get to the bottom of this issue but alas i am at a complete loss. Here is a list of the things i have tried to do to rectify this problem and to save some of you the hassle for yourselves:

1. Cleaned cabin temp sensor
2. Replaced cabin temp sensor with another unit.
3. Had a look at front and rear heater matrix's (matrii?) to see if they were getting hot.
4. Removed dirt from front and rear A/C matrix's to see if made a difference (it didn't)
5. Checked wiring in out of cabin sensor to see if they were getting voltage.
6. Checked all flaps covering matrix's to see if they were operational (only two positions actually worked open (32 degrees) and closed (all other temperatures).
7. Checked all coolant hoses to see if there was an air-lock of sorts.

So....here we are, i am at a total and complete loss, i am pretty sure mine did work at some point as i have had the Bongo for well over a year now and i think it started last Summer, but as it was Summer i really did not need the heater on full tilt hot. So if anyone has any other ideas please feel free to chip in.
Cheers.

jimmo62 · Post by **jimmo62** » Fri Mar 11, 2016 9:45 pm

As posted above - it says in the manual that if you set the controls to Upper Body/Lower Leg mode ("face and feet") you will get cool air from the upper body area and warm air from the leg area. So you probably don't have a fault, that's how it works.... (page 125 in the handbook)

tommyrugrat40 · Post by **tommyrugrat40** » Tue Mar 22, 2016 2:33 pm

After much experimentation that is exactly how the heating works, there is no fault.

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