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[bruce]

I have read the first 50 pages of General Help and have some Idea what my problem may be..

My heater on my 98 2.5 elite is not warming up and has started blowing out cold air, it blows warm at first for a few seconds only..on one post a member was told to see if the two pipes that went into the bulkhead were hot..well on mine the top one is hot but the bottom is cold...please can anyone explain in a child like fashion because I know zero about car mechanics  
Bruce

[A380 Elite]

I to no nothing,

But could it be the thermostat not opening.

I'm sure someone will confidently answer your Q.

[JamesV6CDX]

possible HBV issue

Also worth giving the matrix a flush...

[Grumpy]

it blows warm at first for a few seconds only..

and

the top one is hot but the bottom is cold

This would suggest that the Matrix is partially blocked.

Although there is little flow through the matrix, the heat from the
water will permeate through the matrix, warming the coolant inside
of it and the matrix itself. First batch of air passed through the matrix
will warm up and give you warm air for a few seconds.
As the permeated heat is now removed from the matrix, and the reduced
flow of hot coolant fails to overcome the airflow cooling, the air blows cool.

Disconnect both pipes and reverse flush the matrix. If this fails to cure it,
you should get an increased flow if successful, ask on here about recommended
coolant flush products. I've never used one, so can't recommend one from
personal experience (never believe advertising blurb).

If a coolant flush doesn't cure it, then it's either replace the matrix, or live with
it until the summer.

[Grumpy]

Forgot to add.

If when flushing the matrix, you immediately get a good flow through
it, then that would suggest that you have a restriction in the coolant flow
to the matrix.
The most likely cause is a faulty HBV, that is only partially opening, which
could mean a vacuum problem to the HBV. So don't automatically
condemn the HBV.

You'll know more when you've tried flushing the matrix.

[madmax]

im having same problem with my heater, im gonna try FORTE FLUSH you can get it on ebay, im also gonna replace hbv.!!!!

[bruce]

Forgot to add.

If when flushing the matrix, you immediately get a good flow through
it, then that would suggest that you have a restriction in the coolant flow
to the matrix.
The most likely cause is a faulty HBV, that is only partially opening, which
could mean a vacuum problem to the HBV. So don't automatically
condemn the HBV.

You'll know more when you've tried flushing the matrix.

Cheers Grumpy,

I'll try the flush first..and see how it goes...thanks also to everybody else who gave advice

[mega]

hello bruce it sound to me like you have a problem under the dash with one of the vacume units (the hot/cold actuator unit) because what you are saying was a problem i came across several times in the field.it sound like a nightmare but is a very easy thing to do as it just pulls out and a new one plugs back in with a connecting rod,if you had a matrix problem(blocked)your heater would of got less and less over a period of time and not just stopped,the reason it starts getting warm then drops off is because the vacume bowl is worn and seeps pressure.hope this helps,oh and it on the glovebox side under the dash>right hand drive spec.

[ffcgary1]

Hi bruce i can assure you that mega knows his stuff as he is a gold std vx trained mechanic and one of only two people who would be allowed near my car, try what he says and post up your findings. He is not a bodge artist as generally found at some main stealers.

[bruce]

hello bruce it sound to me like you have a problem under the dash with one of the vacume units (the hot/cold actuator unit) because what you are saying was a problem i came across several times in the field.it sound like a nightmare but is a very easy thing to do as it just pulls out and a new one plugs back in with a connecting rod,if you had a matrix problem(blocked)your heater would of got less and less over a period of time and not just stopped,the reason it starts getting warm then drops off is because the vacume bowl is worn and seeps pressure hope this helps,oh and it on the glovebox side under the dash>right hand drive spec.

Thank Mega..

Just one more question...as i know nothing about motors, will I have to dismantle anything to get to this and what does it look like..sorry for sounding like a thicko..

Bruce

[Marks DTM Calib]

Bruce.

Best thing to do is start at the source of actautor power for the Omega setup....and in the case of the Omega, this is engine vaccum.

So, look in the engine bay, at the rear left you will see the large brake servo vaccum pipe, this has a number of small black plastic vac feeds (3 on later V6 units, 2 on early ones) which carry out various functions. One of these pipes travels across the rear of teh engine bay and attaches to a black vac reservios which is mounted in the scuttle at the rear right (at the rear righ you will see a flap in the plastic that covers the pollen filter, remove the rubber seal a bit and ligt it up...). A further pipe then travels back across the rear of the engine to the bulk head at the back left of the engine bay. Here you will see the two heater matrix pipes, where they pass through the bulk head should be two of these small pipes, the one from the vac tank above the pollen filter should pass through this area to the left of teh pipes adn a further pipe shoudl return to teh right of these pipes adn connect to the top of the heater bypas valve.

Check all these pipes are attached and have no damage.

Theres absolutely no point in buggering about with vac pipes behind the dash until you can confirm that the ones in the engine bay are all good.....coz these are the ones that are most likely to get distrubed and damaged.

I say this because you say the heater matrix pipes are not both hot which sudgests the heater bypass valve is not allowing flow through the matrix at all.

I hear whats being said about the blend motors but, there are two seperate ones, one for passenger and one for driver and I doubt both would fail at the same time

[Grumpy]

I say this because you say the heater matrix pipes are not both hot which sudgests the heater bypass valve is not allowing flow through the matrix at all.

Hmm. Now that's why I reckon there's a reduced flow through the matrix.

If there was no flow, then the heat from the engine would heat the coolant
on both sides of the matrix. You can't have hot water in the block and head,
right next to cold water in the pipe from the matrix. It's all one connected
system.

If one pipe is cold, then there must be a flow, that is getting cooled. If it's
getting cooled enough to give a cold pipe, as Bruce says it is, then to my mind
it's a reduced flow that the blower cools easily.

Whether this is due to a partially blocked matrix, or a reduced flow due
to low vac pressure not opening the HBV fully, I don't know.

Interesting to read Mega's comments ref poor vac pressure failing to hold
the internal air ducts in the correct position. Not thought of this.

Look forward with interest to see what this problem turns out to be. Should be
a useful addition to the knowledge base.

[mega]

hello geezer.if it is the vacume unit you can remove it after the glovebox has been removed and it can be checked with a mitivac or some sort of vacume holding devise that you can see pressure drop off on,but as somebody else has said do check the vac pipes under the bonnet as well and you do have a water cut of valve at the back of the engine that shuts off the water to the matrix when you select cold settings on the heater panel this stops the hot water from the engine entering the matrix so the ac evaporator can work at max cooling without fighting the hot matrix beside it,these do leak and once in a while get stuck but by discriptions ie (gets warm then cold)im sure its an air seeping unit on the hot cold flap.i could be wrong but that has always been the problem when ive came accross it,hope you get it sorted mega ....ffcgary1 thankyou for the nice comment m8 and im a master tech not just gold,,come on get with it,22 years all total on vauxhall how sad am i

[raximax]

i had this problem but the reason was when i fitted the hbv i put the two drivers side pipes on upside down and i was sure they where right have you changed the hbv :question

[ffcgary1]

Mega, that told me