Heater Doesn't Get Hot...

[Donagh]

Hi Guys, time for my semi-regular mystery challenge to the group. ;^)
I have a 2000 HSK.

It's getting cooler here in CT and I went to turn my heater on the other evening and got only cool air. I'm not leaking fluid either from the radiator, engine or inside the cabin from the heater core itself. The level seems to be where is is supposed to be when the engine is cool. The fan works, all of the different air routing configurations work, and 'AUTO' works.

I recently had the intake manifold gasket replaced this summer, and I was wondering if they might have done (or not done) something to cause this problem. As some of you may recall, shortly after the repairs were done, (about a week or so) the 'check engine' light came on. Nothing has changed in the engine's performance, and I'm presuming it might be the O2 sensors asking to be replaced or cleaned, but as I said, there has been no negative effect on the engine's performance. However, might this be a clue?

I do notice one peculiar thing: As I'm driving along, with cool air blowing on me, when I make a sharp turn, I get the hint of warm air for a second, and then it returns to the cool air. It's like, 'Oh, here it finally comes...' and then nothing. Very odd... Perhaps it's some programing thing? I don't know, but I thought I'd start here for suggestions, and to see if this is a garden variety problem with this make/model, before I take it to a service person.

Thanks in advance,

Den Gleason/Connecticut

[Joey4420]

Sounds like who ever did your work, didn't bleed the system and you have an air pocket in the cooling system.

[Donagh]

didn't bleed the system...

Ohhhh, that sounds promising. Are you suggesting that this is something I might (might, mind you) remedy the problem with, by draining my cooling system and refilling it? (fingers crossed!)

[Joey4420]

Park with the rovers front end in the air say a steep driveway or bank.

Open the radiator reservoir and fill as needed, close it and start the engine with the heater on when it starts to warm the engine up, shut down let it cool refill reservoir as needed repeat till it does not require a fill up and the heater is working.

[Donagh]

Thanks Joey! I'll keep you posted!

[Donagh]

Well, I put the car on an upward angle removed the cap to the reservoir, and let the engine heat up with the heater on. The coolant in the reservoir got hotter and eventually expanded to the point where it was being pushed up and out of the opening. So... does that mean that there is no circulation, that the thermostat isn't working, or that that it was installed backward?

[kevin-ct]

Is the book icon diplayed in the HVAC unit? With the engine fully warmed up feel the heater hoses, are both of them hot?

Where are you in CT?


Kevin

[Joey4420]

You have an air pocket in the coolant system this may cause this issue. Please read this again.... I did state to check fluid level add as needed, then put the cap back on... start engine and let get to temp with heater on... After it warms up shut it down.. let it cool down open fill as needed, repeat until it doesn't need filled again.

[Donagh]

Is the book icon diplayed in the HVAC unit? With the engine fully warmed up feel the heater hoses, are both of them hot?

Where are you in CT?


Kevin

Hi Kevin,

I'm in Middletown, CT. The book symbol has been on the heater's display since I purchased the car, over 3 years ago, and the heater worked fine, (as does the AC) Both heater hoses are pressurized and hot after the car has run and warmed up. The level of the coolant in the reservoir when hot is actually a bit above the 'cold' level, and there doesn't appear to be any leakage anywhere, inside or out. What do you suspect? Could there actually be an air bubble or pocket inside of the heater core itself, preventing circulation? For some reason, i don't think it's anything huge, just something simple. But this is not my area of even basic knowledge.

Den

[kevin-ct]

Hi Kevin,

I'm in Middletown, CT. The book symbol has been on the heater's display since I purchased the car, over 3 years ago, and the heater worked fine, (as does the AC) Both heater hoses are pressurized and hot after the car has run and warmed up. The level of the coolant in the reservoir when hot is actually a bit above the 'cold' level, and there doesn't appear to be any leakage anywhere, inside or out. What do you suspect? Could there actually be an air bubble or pocket inside of the heater core itself, preventing circulation? For some reason, i don't think it's anything huge, just something simple. But this is not my area of even basic knowledge.

Den

Den, I am in Ridgefield CT not to far from you. Yes, you may have an air pocket in the system. However, after driving it as long as you have it should have escaped by know.

I think that one of the blend door motors that controls the temperature is not working.

I just have replaced all the blend doors motors on a customer
P38. Have you ever had the codes read for the HVAC system?

Let me know if I can help.

Cheers,
Kevin

[Donagh]

Hi Kevin,
No, I can honestly say that this is the first time I've ever heard the two words 'blend' and 'door' used together a description of a car part. LOL. But I'll tell you what, I had the car repaired by some guys who specialize in Benz repair, not Land Rover. I had to tell them to replace the bolts on the intake manifold when they replaced the gasket. I did the research that they should have. So I have a suspicion that it may have something to do with their repair. I know they replaced the coolant, but they didn't replace the top hose clamp properly and I had a slow leak there until I replaced it myself. (they were probably in a hurry).

I saw someone had posted something about a 'flap' being stuck or jammed in relation to this sort of problem. Is that what you are speaking about? The point is, everything worked fine before I gave it to them, and now... so my first thought is that they might have done something inadvertently, to contribute to this issue.

Could that blend door motor be a 'fuse' that is blown?

[kevin-ct]

Den, Here is a description of the heater unit that I got from Rave.

The heater unit consists of a housing containing a
heater matrix which is connected to the engine cooling
system. As water is circulated continuously through
the heater matrix, the selection of hot or cold air is
controlled by servo operated LH and RH blend flaps
directing the air through or around the heater matrix.
The LH and RH blend flaps operate independently to
allow different temperatures to be set for the LH and
RH air vents. The servo operated distribution flaps
control the flow of air from the heater unit to the outlet
vents. Air distribution is common to both sides of the
vehicle interior.
The two temperature servos and the distribution servo
each incorporate a feedback potentiometer which
provides the Heater ECU with a flap position signal to
enable accurate control of air temperature and
distribution.

[Rovah]

I'm going to jump in on this thread because I have a mystery coolant system issue.

A couple years ago(yeah, I'm that busy, with that many vehicles), I lost heat in the cabin followed directly by the truck overheating. Odd thing was that the coolant level didn't drop.

I finally resurrected the truck last month(partially), and we replaced the following; head gaskets, lifters, valve seals, water pump, front main seal, thermostat.

So, drove the truck on a couple of short rides. Seeemed to be ok. Then we lost heat in the cabin and it started to overheat. Thinking we had air in the system, we let it cool, refilled, etc. Attempted another drive with similar symptoms.

Thinking the radiator might be bad(I've heard stories), I replaced it today. Refilled, warmed, refilled, etc. Drove for about 15 miles with no issue and then cabin heat became variable. Once again the truck got hot.

Our heads hurt from trying to think what is going on! Are we simply dealing with a air pocket in the system that won't go away. Is the water pump just pumping air? Did we get a bad thermostat?

ANY help/suggestions are welcome. I need this truck to work and I've run out of things to replace. Everything in the coolant system external to the block(except the hoses) has been replaced. I'm out of ideas and options. I don't really want to take it to my local cooling/radiator shop because I don't think they're any more mechanically inclined than I am. But if we are dealing with an air pocket-would they have the gear to get it to go away?

Thanks again in advance for any suggestions/help.

Cheers! John

[spacemutt]

Check your passenger....no...wait...you've got LHD cars...er...probably driver side carpet in the footwell. (check both sides just in case they run the pipes in a different direction)

Is it damp?

If so you have a real BAR STEWARD of a job. There are heater hoses running to the matrix that perish and leak causing fluid loss. This could cause an air lock in the matrix. You need long bendy arms to reach them. Either that or send in a small child...

[Rovah]

Thanks Spacemutt-I'll check. Not smelling any coolant in the cab, but I've read about the heater core o-rings over the past few years. I'm sure my day will come-maybe sooner than I want. ;-)