3rd gen HELP HELP HELP- heater

[520ft/lbs-roadeater]

My heater has been only blowing cold air since late summer! My cold morning commutes are becoming a killer! The hose (left one) feeding hot water to the matrix through bulkhead is hot, but the return hose is only warm and the blower is blowing cold to luke warm at best. I have removed the mixer valve thing and bypassed with a straight connector. This improved nothing. But the luke warm air in the cab is still affected by moving the control from hot to cold, it goes from cold to really cold. Is there another valve controlling flow to the matrix? I have had all hoses off and checked for physical blocks and I can blow through the matrix hoses okay, so no blockages. Changed the thermostat and rad cap incase something wasn't letting pressure build up. But it has me stumped and I need to know what else to check or basically remove so I get "HOT" air.....

[Karma Supra]

Edit, sorry you said 3rd gen....

there is a valve before the heater matrix, these can fail and stop the flow (this may be the one you said that you bypassed)

I also had issues on mine of a cable operated valve jamming behind the dash... you can access one end of it from the passenger foot well, on the centre console side at the front.. check that that moves.

Failing that, it may be an airlock.

[520ft/lbs-roadeater]

Yip. That's the valve I bypassed and I have tried twice to chase any air out the system and made no difference. I can remove the return from the matrix and run the engine, the water flow coming out it is rather low until engine is revved. I'm 99% sure it is not a air lock. I have a small heat exchanger on the bulk head that sits higher than the matrix and this is seeing full heat and good flow still. I was hoping someone can say there is another valve before I have to start taking the dash to bits!!

Cheers anyhow.

[yoshie]

I would flush the matrix before pulling it out.

Flushing a matrix with a garden hose or simmilar is often recommened. However, I have never had sucess with this. I would remove inlet and outlet hoses fill the matrix with water and blow through with an airline, ideally with a triggered air blower attachment so you dont put to much pressure through.

[Dobbslc]

What's the matrix on the bulkhead? Is it an extra or something? If so I would take that out the system first, then see if you have hot water flow out the normal heater pipes.
It could be the heater control panel has gone pop and isn't directing any hot air through the vents, the vents are motor controlled not manual wires on the 3rd gen' s as far as I know.
If you take out the radio and surrounding fascia panels you can reach some of the heater gubbings, you might be able to see what's not moving when you switch between screen, footwell, face vents etc.
Just check you have coolant in the heater pipes as if it's full of air that's a sign of a buggered cylinder head.......

[520ft/lbs-roadeater]

The 2nd heat exchanger is for heating my WVO fuel and has been in situ for near 6 years without affecting heaters. But I did hose clamp the feed to this and that would take it out the coolant loop and this change nothing for my issue. I have had both the matrix hose off and can pour water down one then it comes out the other, I can blow through them too. But how easy should I be able to do that? My aircon was totally stripped out a couple years back, well the rad, compressor and any pipes I could chop out. Coolant system was treated to a can of flush stuff and a garden hose rinse about 18 months ago. I need to maybe try flushing the matrix through as Yoshie suggests before jumping in and taking the dash out! Which I would rather avoid tbh. I can't get my head around how the temp control still slightly changes when I have bypassed the control valve for this?

Thanks for the opinions so far... I'll be out with the head torch this evening trying my luck to get some heat for the morning.... ha ha.

[yoshie]

The 2nd heat exchanger is for heating my WVO fuel and has been in situ for near 6 years without affecting heaters. But I did hose clamp the feed to this and that would take it out the coolant loop and this change nothing for my issue. I have had both the matrix hose off and can pour water down one then it comes out the other, I can blow through them too. But how easy should I be able to do that? My aircon was totally stripped out a couple years back, well the rad, compressor and any pipes I could chop out. Coolant system was treated to a can of flush stuff and a garden hose rinse about 18 months ago. I need to maybe try flushing the matrix through as Yoshie suggests before jumping in and taking the dash out! Which I would rather avoid tbh. I can't get my head around how the temp control still slightly changes when I have bypassed the control valve for this?

Thanks for the opinions so far... I'll be out with the head torch this evening trying my luck to get some heat for the morning.... ha ha.

I flushed my Audi with a garden hose on two separate attempts and I used the coolant flush liquid. No change. I then as a last resort before a 10hr dash out and in, adventure used the airline. That was last winter, it fixed it perfectly and since my climate control, dual cabin control and manual control has all been perfect.

All that came out was some clouded water (i had filled with plain water to flush)and a few fish scale sized rubbish. That's all it had taken to totally block my matrix and give me the luke warm at best heaters you describe.

[520ft/lbs-roadeater]

I flushed my Audi with a garden hose on two separate attempts and I used the coolant flush liquid. No change. I then as a last resort before a 10hr dash out and in, adventure used the airline. That was last winter, it fixed it perfectly and since my climate control, dual cabin control and manual control has all been perfect.

All that came out was some clouded water (i had filled with plain water to flush)and a few fish scale sized rubbish. That's all it had taken to totally block my matrix and give me the luke warm at best heaters you describe.

Sounds well worth a try. I will see if I can try so sort of 'forced' flush on the matrix hoses.

Does anyone know if the 3rd gen climate control (auto position) has a seperate valve to control coolant flow through matrix or does it use the main valve on the bulk head that I have already bypassed? Once removed this valve seems to be working fine and will be replaced when I eventually sort things.

[520ft/lbs-roadeater]

Well.... tried flushing out the matrix and giving it a good dose of cleaner and it has made no difference. I have also removed and cleaned the wee cabin temp sensor under the steering wheel and it has made no difference.

If I have removed the coolant flow valve on the bulk head that is controlled by the hot/cold positioning, how do I still get a change in temp from barely luke warm to proper cold when I move the control from red to blue positions? Unless I'm not understanding the heating system quite right! I've been forced into doing the commute in my 500bhp Subaru, fun, but no where near as cheap a WVO fuel in the Surf! The heaters are roasting in the Subaru though. Not sure if they are worth the £80+ on v-power. Ha ha

[KERRSURF]

Did you try with and airline?

[Jameswallace]

Sounds blocked to me. Will water pass freely through the matrix ??

[yoshie]

Sounds blocked to me. Will water pass freely through the matrix ??

Water passed freely through mine and it was still useless. The air line worked a treat

[Jameswallace]

Fair enough! But if water passes through surely it should be heating it up though? (Im not reputing uour answer just curious)

[yoshie]

Fair enough! But if water passes through surely it should be heating it up though? (Im not reputing uour answer just curious)

I flushed mine twice in the normal way and I also used thus two stage chemical flush.
As a last resort I gambled with an air line as it was useless anyway. All I got out was some clouded water and very small flakes. Heater has been perfect ever since.

[Bogus]

Water might pass through freely but any scaling on the tubes can inhibit heat transfer. If you live in a hard water area , or your Surf has, and previous owners have been topping up with tap water, not bothering with a decent coolant mix, all this is quite possible