Heater Maximum Output Temperature - Too Low?

Having read a number of threads and now completed a few checks, I was hoping that someone maybe able to confirm wether or not my heater is performing below spec.

 

The heater is never hot even when the temperature control is turned to max and the fan on full (auto off). The engine runs at normal temerature - gauge always at half way and the heater input and output pipes are both very hot. I have run the engine hot with the radiator cap off for ten minutes or more to hopefully eliminate air locks. I have flushed the heater matrix out in both directions - there wasn't any sign of rust or sediment. The coolent that came out was very clean. The temperature control does move the air mixing flap and changes the air output temperature from cold to quite warm, but not hot like in other cars. When the temperature control is moved slowly with the engine off but ignition on, the air mixing flap can be heard to move right across the range of the temperature control.

 

I have tested the temperature coming out of one vent (passenger RH) with the temperature control set to max and the blower on full, outside air coming in, and the maximum it would read with the thermometer sensor in the vent was 45°C (outside temp was 14°C at the time), an increase of only 31°C. This sounds quite a lot but by comparison with another vehicle on the same day (14°C outside), the vent temperature was well in excess of 70°C. The thermometer wouldn't read over 70°C and displayed HI.

 

If anyone has a digital thermometer and can confirm that my heater is definitely working below what it should, I would be grateful. A solution to the problem would be even better!

 

Apparantly this is going to be a very cold winter!!

That sound way too low. I can check for you in a little while. About ten minutes.

 

May be the core is partially blocked, you could try a rever se flush, gently at first and gradually increasing the pressure.

 

You could try the heater/air con error codes.

Yep sounds like it's clogged up...do as termi says and flush the entire system...concentrating on the martix via the hoses going into the bulkhead.

 

(Attach a garden hose and gently wash it through....then increase the pressure)

Whip out the heater matrix and pop a new one in there.

Thanks for the fast replies.

 

I have already flushed the heater out in both directions, several times over a period of around an hour. Nothing at all came out in the way of sediment, just clean water. The pressure from the hose pipe is quite good and I also tried the pressure washer - although I doubt this would be any better that the hose pipe due to the lower volume of water per minute this can put out compared to the the tap alone. If I had seen some sediment I may have thought that the matrix could be partially blocked, but my feeling is that it is clean.

 

As A last resort I will change the heater matrix - it would probably take me a couple of hours though.

it would probably take me a couple of hours though.

Yeah, probably.

 

Carl0s was saying yesterday that he had got his GF's heater working again with the help of some Bars Radiator Flush. Might be worth a shot.

As A last resort I will change the heater matrix - it would probably take me a couple of hours though.

 

OK just checked air entering vent above the bonnet was 15.5C air from passenger right vent setting on full 60.5C and still rising after 10 minutes.

 

You may need a chemical flush. I tried all you have done on a RS Cosworth and it still was cool. Used a chemical flush and it did improve but not back to normal. Changing the matrix is an abosolute pig and best avoided unless absolutley necessary.

 

I wonder if one of the valves has got stuck and you are reveiving a mix of heated air and ambient air. I think error codes may show this fault.

Thanks for checking the temperature Terminator, that has definitely confirmed my heater is performing poorly. It will be useful info for anyone else with a suspect heater.

 

I forgot to mention previously that I had checked the heater codes and they were normal. I'm probably mentally trying to block out the heater may need replacing - but wouldn't there be some sign of sediment if it was partially blocked?

 

I wondered if the cabin temperature sensor was sending an incorrect signal to the heating ECU and the system thinks that the inside temperature is a lot warmer than what it actually is, resulting in the air mixing flap not moving fully across.

 

I'll check out the sensor and then will have to consider some serious flushing additive!

Hello,

 

I posted a thread on supraforums regardin gthis, I had the same problem, and I have a fix.

 

I guy on this forums tried it too and it worked very well.

 

 

Disconnect the Matrix hoses from the firewall, and try flushing them both ways with a high power jet wash. (Use hose extensions else your bay will be well messy)

 

If that fails to fix it, the only thing I could find to un clog it was Nitrox Drain Cleaner. It is 99% Sulphuric acid so be very careful. You can buy it from B&Q and its about £6.

 

Run some down in there and leave if for about 30 mins, shoudl start to bubble nicly, then rinse through with a hose pipe (not high pressure) from the side you put the cleaner down.

 

Repeat this 3-4 times in both directions untill water flown cleanly.

 

Then Use jetwash again to 100% clean out any acid and crap that is in there.

 

This worked fine for me and continued to work for months untill I have now taken my car off the road.

 

Seems alot easier than changing the matrix!!!!

 

*** Be care full with that drain cleaner , I use welding gloves when using it.

***** Flushing aditives didnt do squat!

Martin

I wondered if the cabin temperature sensor was sending an incorrect signal to the heating ECU and the system thinks that the inside temperature is a lot warmer than what it actually is, resulting in the air mixing flap not moving fully across.

 

Wouldn't that only matter if you had the system set to Auto?

Wouldn't that only matter if you had the system set to Auto?

I thought that the Auto switches controlled fan speed and the airflow output vents only. The air mixing flap should be fully across to the hot position anyway if the temperature control was at maximum - I'm not sure if the internal cabin temerature sensor circuit would have any effect even if faulty.

 

Reading the Toyota service manual at the moment - testing sounds like a Sunday job.

I thought that the Auto switches controlled fan speed and the airflow output vents only. The air mixing flap should be fully across to the hot position anyway if the temperature control was at maximum - I'm not sure if the internal cabin temerature sensor circuit would have any effect even if faulty.

 

Reading the Toyota service manual at the moment - testing sounds like a Sunday job.

 

I think you're right in that the Auto switch only affects fan speed and high/low vent selection, but I also think that this is the only thing the temperature sensor works with, so with Auto turned off, the temperature sensor wouldn't be having any effect.

 

(this is just my thoughts BTW, not saying it's correct)

Sorry in advance for the:hijack: :hijack:

 

My heating is remaining cold, irrelevant of the climate knob's position. Obviously not bothered me over the summer months, though, it's getting a bit chillier in the morning on the way to work.

I've flushed through the heater matrix with the grden hose, and it was relatively clean, the only thing i can think of is the air mix flap is sticking in one position???? what d'ya reckon, and if so....is it easy to get to/free off???

sorry for the hi-jack:whistle:

the only thing i can think of is the air mix flap is sticking in one position???? what d'ya reckon, and if so....is it easy to get to/free off???

Take the left dash panel off. As you turn the heater temperature control (with the ignition on), you should be able to see and hear the air mixing flap actuator arm moving through around 100° of movement from the cold to the hot position. This can be seen by using a torch and looking over the radio to the area behind the passenger air bag panel, on the top left hand side of the heater/ac unit.

 

I checked mine on Sunday and it's ok. My faulty heater is now down to either:

 

1. A broken/damaged air mixing flap. (very unlikely)

2. A bad air lock.

3. The matrix is partially blocked (even though no sign of sediment) as previously stated, and it can't be cleared with a hose pipe or pressure washer.

 

It looks like the drain cleaner option is next for me.

I know three and a half years (exactly) have passed since my post above, but I thought I'd let you know that I did eventually find the problem - about four weeks ago!

 

Hopefully the following may be of some use and potentially save someone a good few hours of wasted time...

 

It did turn out to be the air mixing flap that was causing the problem. When looking from behind the left dash panel (as mentioned above), I could see the actuating arm move ok when the heater temperature knob was turned; what I didn't realise at the time, was that a rod connected to the actuating arm goes down through the heater unit and ends up at point 'A' in the first photo (which is looking up towards the heater unit from the passenger footwell).

 

The actuating arm had come off the air flap lever end as at point 'B' in the second photo (just taken it off again for the photo )

 

It should be connected as in the third photo at point 'C'.

 

After spending quite some time flushing the system out (which was clean anyway), the fix turned out to be very simple and took no more than a minute or so. Anyway, I've now got a heater that when on maximum it could strip paint.

Edited April 24, 2009 by SteveC (see edit history)

Great post, thanks for sharing. "Something" has happened to the wife's Jeep heater controls, possibly a similar sort of fault, but access is all but impossible without ripping the dash apart

Thank you Steve for taking the trouble to post the solution.Just been out to check mine,as the heat was miserly.Mine had come off at point A.Was the easiest fix ever.Mucho kudos.

I'm very pleased that my post turned out to be useful to you... and thanks for the comments.

As far as the Jeep (PO[Yank]S) goes, it seems it has a fault coomn to Chryslers, in that constant ECU self setting of the heater distribution flap has broken it internally. The air blend flap is the one that most usually goes, and the Yanks sell a butcher it repair kit. They don't seem to address the distribution flap though. I may have to cut a big access hole in the heater box with a hole saw or a hot knife and see if the damned thing can be codged back into a place where air can mainly demist the screen, rather than the random blowing from all orifices it enjoys now, as the thing's all but unusable in cold weather. Bring back Bowden cable operated heaters with 2 slides, not this crazy ECU controlled stuff

The problem with faulty heaters Chris, is that most of us only appear to try and sort them out when the weather gets really cold!

 

It's not so bad if you have a heated premises to work in, but it's not so great in temps below freezing point - especially knowing full well that you could have done the job in Summer!

 

Good luck with the Jeep heater repair. Isn't there any good info as to the quickest fix on any Jeep forums? Or, would a complete s/h heater unit be a good option - if not too expensive?

SteveC, many thanks for posting this up, you're a credit to the club.

 

I've only just seen this thread but your symptoms exactly describe mine. My heater is luke-warm only. I've tried flushing the matrix both ways via a hosepipe: water coming out is as clean as a whistle, with zero sediment. I refilled the cooling system with a raised tube to act as a header to eliminate airlocks.

 

I'll take note of your post and have a look. Thanks again.

Edited December 2, 2009 by stevie_b (see edit history)

stevie_b, I hope your heater also turns out to be such a quick fix - and again, thanks for the comments.

 

I had pretty much given up on mine a few years ago, after reading all the comments on here saying that the problem was almost certainly down to the heater matrix with an immovable partial blockage.

 

Apart from spending hours outside in the freezing cold trying to flush the matrix out (only to find perfectly clean water coming out), I also drove the car a few miles away and parked up on a very steep hill, left the engine running for ages with the radiator cap off, in the hope that it would get an air lock out of the system - which also turned out to be a complete waste of time!

 

I've done it before, and most likely I'll do it again - that's just dive in at the deep(ish) end without thoroughly looking for the simple solution first!

 

It could have been far worse I suppose; I could have just taken the dash completely apart and bought a new matrix instead.

I know three and a half years (exactly) have passed since my post above, but I thought I'd let you know that I did eventually find the problem - about four weeks ago!

 

Hopefully the following may be of some use and potentially save someone a good few hours of wasted time...

 

It did turn out to be the air mixing flap that was causing the problem. When looking from behind the left dash panel (as mentioned above), I could see the actuating arm move ok when the heater temperature knob was turned; what I didn't realise at the time, was that a rod connected to the actuating arm goes down through the heater unit and ends up at point 'A' in the first photo (which is looking up towards the heater unit from the passenger footwell).

 

The actuating arm had come off the air flap lever end as at point 'B' in the second photo (just taken it off again for the photo )

 

It should be connected as in the third photo at point 'C'.

 

After spending quite some time flushing the system out (which was clean anyway), the fix turned out to be very simple and took no more than a minute or so. Anyway, I've now got a heater that when on maximum it could strip paint.

 

I owe you big time, man!

 

3 months ago I found out I do not get hot air from heater and was little bit stressed now about it because the fall and winter is coming over to Finland fast and I would freeze my balls off if not getting the heater to work.

 

I searched some info here and did a list what could be the problem.

 

This was #1 on the list and this morning went out to check all the things in my loooong list.

 

Well, turned out it was that metal thingy hanging loose on passenger footwell. Clipped it back and everything is now working like it should again

 

That was like.. 10 second fix. Only because of your great pictures. Please PM your address and I will send you a gift

I'm really pleased FlrSupra that my post was of use and that your balls will remain intact in Winter!

 

There's really no need to send me any gift, but thanks anyway. Just acknowledging that my post helped you have an easy fix was payment enough for me. Thanks.

 

Steve.