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The mkiv Supra Owners Club

heater blowing only warm not hot


girth45

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There's a mechanical link in the passenger footwell that can come unclipped; it happened on mine and the heater would only go warm.

 

I spent ages trying to find the problem and then the fix took just a few seconds by clipping the link back together and I had a hot heater again. The link operates the air mixing flap.

 

You need a torch, head down in the passenger footwell and look up towards the centre of the car. I did a post about it ages ago but unfortunately the photos in the post are missing.

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As David says it would help if you could find out what was fitted, the price your mate paid

should be a good guide as the OE matrix was over £400 back in 2011

 

The aftermarket versions are around £70

 

You could get a pressure check done on the cooling system or fill the expansion tank to a given mark

and check it to see if it drops over a period of time

 

I've attached photos of the flap linkage

24042009021.jpg

24042009022.jpg

24042009026.jpg

Edited by Dnk (see edit history)
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  • 3 weeks later...

Hello Dnk, I have still not had any success with this and would appreciate it if you could have a look. I am near Coventry.

All I can tell you about the matrix is that it was replaced April 2015 , I assume my garage got it from their Toyota suppliers and I was charged £230 for the unit.

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Hello Dnk, I have still not had any success with this and would appreciate it if you could have a look. I am near Coventry.

All I can tell you about the matrix is that it was replaced April 2015 , I assume my garage got it from their Toyota suppliers and I was charged £230 for the unit.

 

Hi, im happy to look at it but have you done any of the checks mentioned above in the previous posts.

 

Does it lose coolant ? Does it have an expansion tank plumbed up to the rad filler neck ? How old is the rad filler cap ? these tend to fall apart

with age and can bugger up the coolant flow that goes in and out of the system as the coolant heats up and cools down

 

Have you checked the control rod is connected ?

 

The price you paid sounds very cheap going on prices i was given for a genuine Toyota matrix

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Hello Dunk, many thanks for such a quick response.

 

I am not losing any coolant and yes, there is a proper expansion tank and the radiator was replaced at around the same time as the matrix.

I'm not sure what you mean by 'control rod' but the garage which I normally use tells me that they have checked everything, all flaps are operational and there is no air in the system, input and output pipes under the bonnet are hot and they think it's either a head gasket or warped head. Which I hope it's NOT !! as you can imagine. I have even changed the heating sensor behind the dash although this was out of a write off and so isn't new but still the same, air is certainly not reaching the right temperature.

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See my post above for photos of the control rod, post 11 and SteveC's post 7

 

I'd have thought if you had headgasket failing it would be losing coolant and have some

tell tale signs of this if it was affecting the heater

 

http://www.mkivsupra.net/vbb/content.php?60-Cooling-System, page CO-18

Edited by Dnk (see edit history)
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See my post above for photos of the control rod, post 11 and SteveC's post 7

 

I'd have thought if you had headgasket failing it would be losing coolant and have some

tell tale signs of this if it was affecting the heater

 

http://www.mkivsupra.net/vbb/content.php?60-Cooling-System, page CO-18

 

Yes, those have been checked and all apparently working as they should.

I'm afraid for some reason I can't see the link, I don't have permission or something

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You possibly need to be a paid up member to view the link

 

Its basically a simple pressure test on the cooling system but if your not losing coolant then i wouldn't

worry about it.

 

I'm not sure why your garage suggest the head gasket being the cause of the poor heater ? how would that affect it

unless you were losing coolant and had air in the cooling system

 

When the engines cold take the rad cap off, is the coolant level sitting in the rad neck ?

 

Does the engine get up to normal operating temp, mine always sat bang in the middle

of the stock temp gauge

 

What was the heater like before you changed it ? Why was it changed ?

Edited by Dnk (see edit history)
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Yes, that does seem to be the problem, unfortunately I'm also having trouble with Paypal, just not my day !!

 

I don't know why they think that but I would feel happier if I could resolve this heating issue then at least I would know they were wrong.

 

Yes, the coolant is full when cold.

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Sorry, missed your last bit.

 

Yes, the temperature gauge appears normal, it may just minutely below the halfway mark but that may be my imagination, it is always steady at the same level.

 

The heater matrix 'blew up' about a week after I'd had the car, about 1/4 mile away from the motorway junction, luckily not in the middle of the motorway.

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Sorry, missed your last bit.

 

Yes, the temperature gauge appears normal, it may just minutely below the halfway mark but that may be my imagination, it is always steady at the same level.

 

The heater matrix 'blew up' about a week after I'd had the car, about 1/4 mile away from the motorway junction, luckily not in the middle of the motorway.

 

Sorry i edited my post a bit :)

 

I assume the engine didn't over heat when the matrix went pop ?

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If it had overheated then it could of damaged the head gasket but then for it to affect the cooling system i'd expect

it to be losing coolant either into an oil gallery, a cylinder or too the outside of the block

 

But if its not losing coolant that kind of rules that out

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guy fawkes, this isn't your car I have in for heater / coolant issues is it??

 

 

(I have a MKIV TT in for poor heater output and excess and near immediate pressurisation of the engine coolant. A dye test and a sniff with the 4 gas analyser showed combustion gasses in the coolant, and revving the engine slightly showed a myriad of fine bubbles forming in the header tank. Head is off, no obvious head gasket failure, but I have seen plenty of N/A's do this, the bubbles in the coolant cavitate the water pump and the water fails to circulate properly. Next step is a pressure test of the head, which is warped, and if it passes, a skim and crossing of the fingers. I also need to hardness test it as the owner states it was over heated in the past, but "not much" :) )

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