Heater Not Hot

[SteveLS400]

Chaps

As Ive probably mentioned elsewhere, I had the aircon on my 95 MK3 completeley refurbed a year or so ago.

It would not gas-up and thus required rather more than a £45 Kwik Fit. Off it went to a specialist, and as most of the kit is behind the dash, dash was out. I was and remain pleased with the job, cold is cold. However, hot aint necessarily hot.

Prior to the refurb, I always had it set on 20 degrees auto, with or without aircon. Since the refurb, to get really warm it needs setting at 27 or above. It also ocaisionally makes groaning noises (mechanical not gurgling water noises).

The short question is why? The longer question is what can I do to rectify it? Am I right to assume its a dash out job? If so, does anyone have a link to its removal and replacement?

Incidentally, I do keep the sensor clean on the underside of the dash.

Steve

[ROYT]

Is your engine temp. normal when hot?

If not it may just be the engine thermostat

[SteveLS400]

Is your engine temp. normal when hot?

If not it may just be the engine thermostat

Thank you for getting back to me, see my posts about temperature gauge, but before it packed in the temp was always the same when fully warmed up and, on the rare ocaissions that it has worked since, its not been a problem.

[ROYT]

Before you start dismantling the dash, check for airlocks in the heater system.

Can you hear all the flaps and vents moving inside, when you change the air distribution?

[steve2006]

Also check the heater flow valve which is situated on the rear engine bulkhead behind the intake manifold/plenem chamber. There should be a plastic cover on it and once removed you will see the valve.

With the heater on check that both the inlet and outlet hoses are the same temperature if the outlet is cooler try opening the valve manually or get someone in the car to reduce and increase the temp and see if it activates the valve.

Another thing worth checking, the outside temperature display is it accurate? If not this could confuse the system.

[SteveLS400]

Also check the heater flow valve which is situated on the rear engine bulkhead behind the intake manifold/plenem chamber. There should be a plastic cover on it and once removed you will see the valve.

With the heater on check that both the inlet and outlet hoses are the same temperature if the outlet is cooler try opening the valve manually or get someone in the car to reduce and increase the temp and see if it activates the valve.

Another thing worth checking, the outside temperature display is it accurate? If not this could confuse the system.

Thanks Steve, and indeed Roy. I will check this out when I get a moment and report back.

No, the outside temp has always been pretty accurate.

Steve

[SteveLS400]

Also check the heater flow valve which is situated on the rear engine bulkhead behind the intake manifold/plenem chamber. There should be a plastic cover on it and once removed you will see the valve.

With the heater on check that both the inlet and outlet hoses are the same temperature if the outlet is cooler try opening the valve manually or get someone in the car to reduce and increase the temp and see if it activates the valve.

Another thing worth checking, the outside temperature display is it accurate? If not this could confuse the system.

Thanks Steve, and indeed Roy. I will check this out when I get a moment and report back.

No, the outside temp has always been pretty accurate.

Steve

Chaps. Its the baby's 15th b'day today and to celebrate she's had a wash a full tank!

Right, whilst attending to the temp gauge issue (see below and my other post), we had a look at this.

At the rear of the engine we found a valve. Of the 2 pipes, the top 1 connected to this valve and it was quite warm maybe even hot although it wasn't flesh-meltingly so. The lower pipe was significantly cooler. The valve I'm referring to has a cable connection. Operating the temperature control in the car from Max Cold to Max Hot had the cable move the valve throughout the full extent of its travel (as seen by removing the cable and operating the valve from under the bonnet). The airflow into the car is via the appropriately selected direction ie screen, feet etc whether via manual selection or when on automatic climate control. The fan appears to cut in correctly as well. Does this enable a better diagnosis?

To save looking at my other post on the temperature gauge, and for completion, I will explain here as there may be a link although I can't see it.

The temperature gauge has always read at the "half-full" mark when fully warmed-up. It might have gone up a thou in traffic in hot weather but that was that In June last year at Le Mans 24H we needed to plug the laptop in and have a meeting. As it was stinking hot we sat in the car with the engine idleing and the aircon on. After 45 mins or so I noticed the temp gauge nudging the Hot so shut dowm and opened bonnet. At no time it lose any coolant and the temp gauge worked fine on the return to home and indeed for 3 months afterwards. Since then I have not had a reading, nil, nowt. Given that the aircon overhall ( and cooler heater) took place in July 2007 and the temp gauge packed-in in Sept 2009 I cannot see any connection but...

Whilst testing the work done on the temperature gauge today, I took the car out on a couple of occaisions on a journey that would absolutely guarantee normal operating temperature even though air temp was only 4c. The gauge only read "quarter" but at least it was reading. But I noticed that the top hose - along its length - wasn't hot, rather more tepid. Whilst I cannot see any connection between the aircon overall and the temp gauge, I can see a connection between a tepid top hose and a not very hot heater. What to do about it, I don't know.

Views gratefully received.

Confused.

[ROYT]

Is the fluid coupled engine fan, the big un behind the rad. seized and running at full speed all the time?

Is the engine thermostat stuck open?

[SteveLS400]

Is the fluid coupled engine fan, the big un behind the rad. seized and running at full speed all the time?

Is the engine thermostat stuck open?

Hi Royt

Tell me more about the fan please. I thought it ran all the time. It certainly was when I was sqeezing hoses this afternoon.

Steve

[ROYT]

The big fan is fluid coupled, the fan starts with the engine but only runs slow,

as the engine [and the coupling] heat up, the fan picks up speed to give the right cooling effect

at all engine temperatures.

[Ronan]

Two items of discussion here have peaked my interest on my search to sort out the heater in a 2001 LS430 with circa 155k miles onboard. Firstly the question as to whether the temp gauge differed when the non heating problem occured and secondly the fluid coupled cooling fan.

Here is my present dilema, during the recent cold snap here in the West of Ireland the heater stopped working (or should I say didnt start working) one morning while the temp outside was below zero and the windows were all iced up(-2 to -8 range over the previous night). It was someone else driving the car when it happened so I didnt get to see the problem first hand until I had to drive the car on a long (very cold without the heater) journey. Every now and then, of its own accord, the heater kicked back in again from cold start or during the journey but never for very long. For a few days, at that time, it would decide of its own valition whether to work or not (I hate blasted intermittant faults). That was prior to the New Year.

When the car was taken out a few days in to the New Year the heater remained cold on all settings , all sorts of cold air through each and every one of the different vent choices and hasnt heated up since (thankfully the heated seat was still working so it wasnt all bad, brrrr). The new problem however is that the temp started to rise towards the upper end of the scale on short journeys!

Question 1 IF it is a thermostat problem would that lead A) to the heater not heating up, AND B) to the temp rise on the guage? If so could somebody explain the link?

Question 2 Why doesnt the Fan manage the cooling from the sensor?

Question 3 How would one diagnose the thermostat problem?

[SteveLS400]

The big fan is fluid coupled, the fan starts with the engine but only runs slow,

as the engine [and the coupling] heat up, the fan picks up speed to give the right cooling effect

at all engine temperatures.

RoyT

I have given the fan the once over whilst cold. It turns easily by hand. Am I right to assume that if it was buggered, it would turn when cold?

Steve

[SteveLS400]

The big fan is fluid coupled, the fan starts with the engine but only runs slow,

as the engine [and the coupling] heat up, the fan picks up speed to give the right cooling effect

at all engine temperatures.

RoyT

I have given the fan the once over whilst cold. It turns easily by hand. Am I right to assume that if it was buggered, it would turn when cold?

Steve

Ive also had chance to start her up and run her till she's (the new) warm. The fan ran at the same speed as the engine turned throughout the test; it definately didnt slow down on its own accord.

Steve

[SteveLS400]

I have given the fan the once over whilst cold. It turns easily by hand. Am I right to assume that if it was buggered, it would turn when cold?

Steve

Incorrect assumption, if it was buggered then it would be 'coupled' when cold and hard to turn, if it turns freely when cold then it's working as intended.

The coupling gets progressively more direct as it heats up.

Thanks. I think thats what I meant to say but I'm not sure

So, for the avoidance of doubt. The fact it turns freely with the engine off, suggests its ok?

I think I'm going to progress matters by trying to ensure that I do not have an airlock. I didnt personally change the coolant and my man can't remember when he did, if he followed the full procedure; it was a couple of years ago.

Steve

[ROYT]

Devon-LS......... Is that a technical term similar to knackered?

RONAN LS 430.........sounds like the engine thermostat, but this is a wild guess......

know nothing about a 430

STEVE, sounds like the fan is OK, go for air locks and engine thermostat checks...

[dan_t]

For what it'll cost why not replace the Theromostat and the Temperature Transmitter?

[Mybikesacx500]

My tuppenseworth says it sounds awfully like an airlock.

If it happened just after the really cold weather started, perhaps a pipe froze? your antifreeze is up to scratch?

[SteveLS400]

It actually started well before the cold weather so no connection there.

Anyway, Ive bit the bullet. She's booked in for a flush, a new thermostat and a correct refilling procedure on Tuesday. Next riveting installment will follow.

Steve

[Ronan]

Thanks for the replies,

Is checking for an airlock as easy as squeesing the pipes or would one have to drain the system and refill?

As to the antifreeze being ok, I can only sumise that it is, had a full service history, or so I was told by the outlaws but will have to check!

I might try and boil the thermostat,

TY again

R.

[SteveLS400]

Thanks for the replies,

Is checking for an airlock as easy as squeesing the pipes or would one have to drain the system and refill?

As to the antifreeze being ok, I can only sumise that it is, had a full service history, or so I was told by the outlaws but will have to check!

I might try and boil the thermostat,

TY again

R.

Infact, by removing the thermostat, you will lose no-end of coolant. If you follow the correct procedure when refilling it should eliminate airlocks. Given you cant squeeze the inside of the heater, it is the only way that my research says works.

Steve

[SteveLS400]

It actually started well before the cold weather so no connection there.

Anyway, Ive bit the bullet. She's booked in for a flush, a new thermostat and a correct refilling procedure on Tuesday. Next riveting installment will follow.

Steve

Delighted to say that I know have a hot heater