Discovery 4 heater

This site contains affiliate links for which LandyZone may be compensated if you make a purchase.
N

niffty10

Member
Posts
14
Location
Medway. Kent
Hi all, i have just got a 62 plate 3.0 Discovery 4
The heater will not blow warm air, fans work fine, air con is very cold, controls claim they are working but no heat at all, engine comes up to temp quickly enough and sits perfect in the middle
Anyone had this or know where the problem might lie.
Tia
 
Hi and welcome to the asylum

first thing would be to check the water level in ur expansion tank, ensure the vents have no air in the pipes , if that’s ok u may have

an air lock , or the heater matrix is blocked , with the engine hot can u feel the flow and return pipes on the heater matrix where they go through the bulkhead

if u got it from a garage there’s normally some form of warranty so would call them

see how u get on and hope that helps a little
 
Last edited:
I'd run a diagnostic on the HVAC system to see if any servo motors are showing faults. You want to be looking at the blender motors, which are responsible for diverting air through or around the heater matrix.
 
niffty10 said:
Hi all, i have just got a 62 plate 3.0 Discovery 4
The heater will not blow warm air, fans work fine, air con is very cold, controls claim they are working but no heat at all, engine comes up to temp quickly enough and sits perfect in the middle
Anyone had this or know where the problem might lie.
Tia
Click to expand...
Hi, isnt the de-frost LED flashing? cos if it is there is a problem with the stepper motors which are controlling the air temperature for the outlets, if you feel skilled enough to fix it yourself see exactly how the system is working(important for you is page 5) http://gershon.ucoz.com/LANDROVER/DISCO4/Heating_and_Ventilation-Heating_and_Ventilation.pdf , if no visual warnings IMO it's most likely something related to what gstuart said
 
Thanks for the info guys, i have bled the system several times with no joy, maybe it has an air lock that i haven't managed to move yet.
I will track down the flow and return tomorrow to see if its circulating through the matrix.
No flashing led's anywhere but i did wonder if it might be the motors that move the heat around, i am assuming its dash out if its the Matrix or the motors.
 
Evening gents
Interesting update on the heater problem, had a local mobile mechanic look at it today, first thing he noticed is the egr valve isn't very old.
He plugged it in and found a load of stored faults relating to the heater.
He said they most likely relate to a recent flat battery which also showed up on the same date, he cleared the faults and run the car for a while.

One fault come back quite quickly, It reads (HEATER LOCKED OUT) he cleared it several times and it comes back, there is no hot water circulating
the heating system at all, he has bled it to within an inch of its life thinking a censor might be picking up no water where an air lock might be sitting in the system and still the same fault and still no hot water moving.
The rest of the engine has hot water moving around and all the hoses are hot, radiator is hot just nothing happening in the heater system, the mechanic is half convinced the pump next to the fuel burning heater is at fault but cant be sure.
Any suggestions to point us right would be appreciated.
 
Evening gents
Interesting update on the heater problem, had a local mobile mechanic look at it today, first thing he noticed is the egr valve isn't very old.
He plugged it in and found a load of stored faults relating to the heater.
He said they most likely relate to a recent flat battery which also showed up on the same date, he cleared the faults and run the car for a while.

One fault come back quite quickly, It reads (HEATER LOCKED OUT) he cleared it several times and it comes back, there is no hot water circulating
the heating system at all, he has bled it to within an inch of its life thinking a censor might be picking up no water where an air lock might be sitting in the system and still the same fault and still no hot water moving.
The rest of the engine has hot water moving around and all the hoses are hot, radiator is hot just nothing happening in the heater system, the mechanic is half convinced the pump next to the fuel burning heater is at fault but cant be sure.
Any suggestions to point us right would be appreciated.
 
Heater locked out would suggest to me the fuel burning heater is locked out and not the main cabin heater.
Is the fbh running? think with engine running the fbh runs when outside temp is under 7 degc.

Is the heater a full flow type? ie the matrix runs hot all the time , and the temp is controlled by the flaps, if so and you have hot water in and hot water out, that only leaves the heater box/controls.

Tried a hard reset?
 
lynall said:
Heater locked out would suggest to me the fuel burning heater is locked out and not the main cabin heater.
Is the fbh running? think with engine running the fbh runs when outside temp is under 7 degc.

Is the heater a full flow type? ie the matrix runs hot all the time , and the temp is controlled by the flaps, if so and you have hot water in and hot water out, that only leaves the heater box/controls.

Tried a hard reset?
Click to expand...

It appears you could be right about the fbh being locked out, the most popular reason for it locking out is it needs de-coking.
It is full flow but we have no flow at all in any heater pipes, everything else in the system is working fine.
 
niffty10 said:
It appears you could be right about the fbh being locked out, the most popular reason for it locking out is it needs de-coking.
It is full flow but we have no flow at all in any heater pipes, everything else in the system is working fine.
Click to expand...

Main reason for fbh lock out is low fuel, under 1/4 tank and they do not start, do that enough times and they lock out, clearing the codes does normally unlock them.

If it is full flow then I would suggest the old trick of disconnect heater pipes under bonnet and flush the matrix both ways with the hose pipe, cannot really seeing it being blocked as its still quite a new car in my eyes, but who knows what previous owners have done?

Have you ever changed the stat?
Iirc the egr valves also have their own stats, not sure if this would effect the heater though?

Can you see a stream of coolant moving in the header tank when its running?
 
lynall said:
Main reason for fbh lock out is low fuel, under 1/4 tank and they do not start, do that enough times and they lock out, clearing the codes does normally unlock them.

If it is full flow then I would suggest the old trick of disconnect heater pipes under bonnet and flush the matrix both ways with the hose pipe, cannot really seeing it being blocked as its still quite a new car in my eyes, but who knows what previous owners have done?

Have you ever changed the stat?
Iirc the egr valves also have their own stats, not sure if this would effect the heater though?

Can you see a stream of coolant moving in the header tank when it’s running?
Click to expand...

Defiantly have flow at the header tank and the egr valve looks very new and you can see it’s all been disturbed recently. We thought the same about being blocked at it’s age, saying that the power steering fluid is black so it’s possible someone really didn’t know what they were doing, got to change that fluid before it goes back on the road. I am going to try flying it on Saturday Thanks for your help.
 
niffty10 said:
Defiantly have flow at the header tank and the egr valve looks very new and you can see it’s all been disturbed recently. We thought the same about being blocked at it’s age, saying that the power steering fluid is black so it’s possible someone really didn’t know what they were doing, got to change that fluid before it goes back on the road. I am going to try flying it on Saturday Thanks for your help.
Click to expand...

I had to read that twice, I think you meant flushing and not flying:)
Be interesting to see how the water flows through the matrix, not sure what the hosepipe pressure is like in your area?
 
Hi

have also heard a few other things with regards to the heater not working on the D4

1) by using a pressure tester to push any air out

2) FBH control valve stuck closed/ failed

if u have an air compressor that can produce a min of 90 PSI there is also a coolant flushing gun that uses water and air to aid flushing out a heater matrix on both ports , no guarantee but are only around £20

hopefully at the end of the day it’s an easy fix
 
Last edited:
gstuart said:
Hi

have also heard a few other things with regards to the heater not working on the D4

1) by using a pressure tester to push any air out

2) FBH control valve stuck closed/ failed

if u have an air compressor that can produce a min of 90 PSI there is also a coolant flushing gun that uses water and air to aid flushing out a heater matrix on both ports , no guarantee but are only around £20

hopefully at the end of the day it’s an easy fix
Click to expand...


Where would i find the fbh control valve, the guy who looked at it for me was suspect of the of what looks like a pump that mounted behind the fbh, it has two hoses connected to it, i was thinking about connecting the two pipes to bypass the unit to see if it allowed a flow.
 
niffty10 said:
Where would i find the fbh control valve, the guy who looked at it for me was suspect of the of what looks like a pump that mounted behind the fbh, it has two hoses connected to it, i was thinking about connecting the two pipes to bypass the unit to see if it allowed a flow.
Click to expand...

Surely feeling the hoses or using an infra red heat gun (cheap off ebay) would tell you if coolant was flowing?
All that elec water pump does is allow the hot water to be pumped around the system mainly in preheat mode, ie engine off, I dont know if it runs with the engine running? I suspect it does.

But and here may be the thing to look into, I think the d4 allows the interior heater to run when the fbh is running so the car is warmish when you start it up, but I dont know how it controls the flow of coolant?
 
Last edited:
You must log in or register to reply here.

Similar threads

E
Discovery Sport cabin temp sensor fan location?
Replies
1
Views
654
Graculus
Graculus
deangermouse
L320 Lack of heat in the cab
Replies
0
Views
192
deangermouse
deangermouse
M
Discovery 4 - Limp Mode Cold Start Manifold absolute pressure issues
Replies
2
Views
420
Graculus
Graculus
Lazydave
Disco 4 (LR4) SOLD Discovery 4 HSE 2010 for sale £5250 ono
Replies
1
Views
674
Lazydave
Lazydave
v8roar
Heater issues
Replies
9
Views
1K
tilly2
T
Back
Top