no heater

[harrylime]

I'm having a couple of niggles at the moment. Took my 99 LS400 out today and the temp gauge rose as normal (almost to halfway), but got no warm air from the heater. Can anyone suggest any obvious checks, other than coolant level?

[ambermarine]

Hi Hugh

There may be a servo inoperable in the system, the heater is forced fed from the water pump unless a gate valve is closed .The gate is opened by a servo when you switch your heater on.Switch on the ignition and  the heater on and off,you should hear a servo operating.

Also check there is not an airlock in the cooling system the way to do this is release the relief valve by the outlet hose at the top front of the engine make sure the engine is cold when you start this procedure and take off the expansion tank cap if there is any air trapped in the system it will as the engine warms up escape through the venting nut at the front of the engine,the thermostat opens as the engine warms up and coolant and air should be seen escaping it will only take a couple of minutes if there is an air lock.

[harrylime]

1 hour ago, ambermarine said:

Hi Hugh

There may be a servo inoperable in the system, the heater is forced fed from the water pump unless a gate valve is closed .The gate is opened by a servo when you switch your heater on.Switch on the ignition and  the heater on and off,you should hear a servo operating.

Also check there is not an airlock in the cooling system the way to do this is release the relief valve by the outlet hose at the top front of the engine make sure the engine is cold when you start this procedure and take off the expansion tank cap if there is any air trapped in the system it will as the engine warms up escape through the venting nut at the front of the engine,the thermostat opens as the engine warms up and coolant and air should be seen escaping it will only take a couple of minutes if there is an air lock.

Many thanks for taking the time to respond. I have something to try now and appreciate that. I want to eliminate the simple things before taking it to the garage

[harrylime]

I have checked the servo, as suggested (another little bit of knowledge gained). It sounds as though it is working, when I adjust either the driver's side temperature levels or the passengers side temperature. I have discovered that my Battery is faulty, but can't think of a way in which this might affect the heating?

The Battery is still under warranty, and my dealer has the Battery for an overnight charge and test, as they need to produce a printout to claim the Battery replacement. I hope it comes back as faulty, because en route to the dealer, I had the Battery tested at two different places, including Kwik Fit. Both tests concluded that the Battery has a dead cell.

I had no air con for a while, and it took several garage visits, new pipes, seals etc. to get that working . The air con is working great now, but I have no heat.

[steve2006]

Mounted on the rear engine bulkhead is the heater valve, this may have a cover fitted but there is a rubber water pipe entering from the bottom and one from the side, the vavle controls the flow of hot water from the engine to the heater.

The operation is mechanical with a control cable from a servo motor opening and closing the valve dependant on the heater temperature settings.

Check to ensure this valve operates when hot and cold settings are selected, the cable c,an be removed and the valve operated manually to confirm either the valve itself is at fault or the control system.

 

[harrylime]

Thanks for the responses, Phil and Steve,I do appreciate it. I checked for a noise when changing the temperature and got a noise, so the solenoid seemed to be working. I then found the valve described, on the bulkhead, and watched it while my wife altered the temperature up and down. Both heater pipes were hot so it pointed to the valve as the culprit (although I was worried it might be a problem with the heater matrix).. I removed the cable this morning and manually worked it up and down a few times, it was obvious it was not moving its full length of travel. I applied some WD 40 and reconnected it, and it seems to be working fine now, with a nice hot heater in the car. This is important, as I am expecting to have to take a longish trip to Wales, and have bad memories of cars with no working heater (Morris Traveller and Mk 2 Jag)

It was a simple fix, as most things seem to be with the 400, touch wood.

[Scribe]

Steve/Hugh, my heater seems to reach temperature when expected but doesn't sustain it for long.  Turning the temperature up doesn't seem to do much, and you have to wait for it drop quite a bit before the heat returns.  Could this be a valve issue, or a thermostat?  (The engine temperature gauge is where it should be.)  Should I try what Hugh's done with the cable?

[harrylime]

I would find the heater valve near the bulkhed, disconnect the cable (easy), then turn the valve (it's shaped like a quadrant) to its highest point. This is on full. If you have consistent high heat, this narrows it down the the cable or the solenoid (which you can hear if it operates). I believe my cable may have been kinked somehow, I have to manuall lift it to the top position until I have a proper look at it, I can then turn it down to the required position using the controls as normal

[Scribe]

Thanks.  Will have a look, or ask my mechanic to.  Apart from that and the key issue, it was 450 miles of effortless travel and of course the car didn't miss a beat.  Averaged 34 mpg, too.