Hello

Having an issue with my heater if anyone can help!

Car is a 2003 4.4 V8, it's a heater issue where the heater blows luke warm or cold on any setting other than maximum (28 degrees) where it will blow hot, basically it's either red hot or cold with no in between. I always check coolant level and it hasn't dropped so don't think there's a leak anywhere and the heater matrix pipes that run into the cab are all hot, obviously hot water is getting there because it works on full. Checked for air in system and it seems ok so a little bit stumped now. Has anyone else had same/similar problem before? Only thing I'm not sure of is if air con needs re gas but would this affect the heater? Also does it regardless of what setting heater is on (manual or auto , feet , screen or mid vents)

Thanks

Hi there i am facing almost the same problem.Difference is that i donot have warm air at any stage.Hot only when at max temp and from 27 and below only cold.
Unfo RR Greece is unable to find what is causing such a problem. They have changed all the relevant sensors even the twinvalve in engine bay but nothing has changed so far.
Their last suggestion was to change the heater-a/c panel as "might be defective"
In a last effort,as i am already fed up with this problem, have ordered a new panel from ebay and as soon as i will install it i let you know if this was the problem or just another waste of money.

I don't know about the 'hot on max' aspect, but I would check the final stage resistor. Only Range Rovers since 1988

Ok thanks, let me know how you get on with the face plate swap. Not sure about the FSR , I thought this controlled fan speed?

When my 2004 4.4 ceased to heat I had the FSR changed and it worked again, beyond that my technical knowledge is inadequate I'm afraid. Only Range Rovers since 1988

Has anyone else had this problem and managed to solve it? I’ve changed the valve on the passenger side wing and made no difference, also the final stage resistor. The heater works as it should for a couple of miles after cold start up then it just goes colder unless you put the temperature setting on max then it’s like being in an oven. I thought it could be air locked but if it was surely it wouldn’t work at all. The weather is cold at the min and this is really bugging me , on the plus side when summer comes around the air con works a treat.

I've had a no heat problem for three years. Last week I found out I didn't have a heater problem, I had a user error problem.

After poring over the workshop manual, checking coolant line temps, wondering if I had an auxiliary coolant pump fault, etc, reading threads on this forum, I found that the central horizontal control adjusted the heat for all face level vents and for the footwell vents. I mistakenly thought it only controlled the temp on the centre vent.

I set it to max and I now have heat (not needed lately with our daytime temp up in the 41-43 deg range.)

EDIT: I was wrong.

It's cool today (26 deg C/79 deg F) so I thought I'd try the heater whilst driving to my local LR independent. Like the others, mine only puts out heat when set to max temperature. Ron B. VK2OTC
2003 L322 V8 Auto
2007 Yamaha XJR1300
Previous: 1983, 1986 RRC; 1995, 1996 P38A; 1995 Disco1; 1984 V8 County 110; Series IIA

Coming home I thought I try something. I turned off the air-conditioning and got an improvement in heating.

I guess I was so used to the way the air con worked in the P38A that I'd never considered turning off the A/C. The P38A seemed to be better.

I'm not sure if the A/C doesn't heat that well when it thinks it's already warm, e.g., 26 deg C.

When it cools down later tonight, I might play again (it's 27C now and might cool to 21C by midnight).
I'm tempted to put T4 on the system to recalibrate the blends flaps. Ron B. VK2OTC
2003 L322 V8 Auto
2007 Yamaha XJR1300
Previous: 1983, 1986 RRC; 1995, 1996 P38A; 1995 Disco1; 1984 V8 County 110; Series IIA

Hmmm.

It didn't get cold enough to get any different results.

I put T4 onto the system but couldn't find where to force calibrate the flap motors as indicated in the workshop manual (see below). I think I might try Faultmate on the system. It makes a lot more parameters viewable than T4 does. I don't know if one can do any of this with the GAP IID tool - maybe I should read the instructions again and try it, too.

From the description, it's unlikely forced calibration would be needed but one never knows with Land Rovers!

Quote:

None of the stepper motors incorporate a feedback potentiometer. Instead, the ATC ECU determines the positions of the flaps by using either their closed or open position as a datum and memorising the steps that it drives the individual stepper motors. Each time the ignition is switched on, the ATC ECU checks the memorised position of the stepper motors against fixed values for the current system configuration. If there is an error (e.g. after a power supply failure during operation or after replacement of the ATC ECU), the ATC ECU calibrates the applicable stepper motors, to re-establish
the datums, by driving them fully closed or open before re-setting them to their nominal position. A calibration run can also be invoked using TestBook/T4.

When any of the control flaps are set to fully closed or open, the ATC ECU signals the related stepper motor to move the appropriate number of steps in the applicable direction. To accommodate build tolerances and wear, and to ensure the flaps are held in the selected position, every 20 seconds the ATC ECU signals the stepper motor to move an additional 10 steps in the relevant direction.

It was cold (23 deg C/73 F) and wet today so I thought I'd try the heating again..

It simply doesn't provide much heat unless the controls are set to maximum and, preferably with the air con off.

I don't know if that's how they all are if some of us have a problem.

When winter comes I might have to add the accessory I used to carry in my '38 Vauxhall - a blanket to put over my legs! (Or I could buy a pair of long pants.) Ron B. VK2OTC
2003 L322 V8 Auto
2007 Yamaha XJR1300
Previous: 1983, 1986 RRC; 1995, 1996 P38A; 1995 Disco1; 1984 V8 County 110; Series IIA

Last edited by p38arover on 8th Jun 2023 8:47am. Edited 1 time in total

Have you both done the thermostat?

Asking for a cold friend.... aka any passengers of mine

My heater works as it should until the engine is up to full running temp. I changed both the circulation pump and heater valves just to be sure....unlike others its my drivers side that is permanantly hot hot hot. Passenger side adjusts as it should. Drivers side burning hot.

ohuntsman wrote:

Have you both done the thermostat?

Was the 1st thing i did when i bought it. Im going to check the lpg vapouriser hoses have been connected up to the correct pipes when its a bit warmer and get the aircon regassed.

No mines not had the mod done, the heater did start working normally again the other day for a trip to Lincolnshire and back from Leeds then went out for a short trip yesterday and normal service had resumed