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        General >> Problems >> Cold Heater - Link with Temp gauging?
        
(Message started by: Headscratcher on Feb 7^th, 2008, 6:23pm)

Title: Cold Heater - Link with Temp gauging?
Post by Headscratcher on Feb 7^th, 2008, 6:23pm

My 2.3 Ultima heater now barely puts out any heat, and from time to time the temperature gauge dips from its normal mid position to the top of the blue and returns over about 20 seconds. There is an occasional shortish squeak from behind the centre fascia as though a bearing is rubbing in the heater controls. I've reset the aircon multiple time (no error code), but sometimes the airflow drops almost to nothing. I've used a flushing compound, back flushed the heater matrix with the garden hose, changed the thermostat and the gauge sender, had the aircon gassed up (it was very low), and checked the bulkhead multi connector. The cooling system is not leaking. I've tried all the techniques listed on this forum save for changing the matrix, and got some heat back for a while. However, I've now run out of ideas. I suspect my next step is to change the heater matrix, although there
was no sign of any deposits when I used the flushing compound, but I can't help the nagging feeling that the unstable gauge and the lack of heat are linked. When I run the instrument panel diagnostics, Engt reflects the movement of the gauge. Is there a possibility that the heater/aircon unit has a defective flap which is bringing in fresh air rather than heated air, and this defect is also causing an electrical problem which in turn is affecting the interface with the temp gauging system?

Title: Re: Cold Heater - Link with Temp gauging?
Post by Snoopy on Feb 7^th, 2008, 7:18pm

Do the heater pipes in and out get equally hot? , but from your explantion of the fault I would most certainly check the thermostat first they can stick open and that results in several syptoms one of which you describe with the temp gauge reading .. The other thing to do is to check the BIG multi plug on the offside wing , the one with the nut holding it in and carefully and I mean carefully clean the pins , possible by using some switch cleaner and plugging and unplugging a few times .

What sort of reading do you get on the dash diagnostics for engine temp.?

From memory it should be in the 110/130 as its a digital readout with 255 being cold and 0 being boiling.

Title: Re: Cold Heater - Link with Temp gauging?
Post by Headscratcher on Feb 7^th, 2008, 8:05pm

As above, changed thermostat and cleaned multiconnector. EngT changes as expected with needle position 130 in middle, 160 ish towards blue.

Title: Re: Cold Heater - Link with Temp gauging?
Post by Tompion on Feb 7^th, 2008, 9:04pm

Sounds like it could be the blower fan seizing, what happens if you turn the fan up high on manual, should give a good blast of air. Have a look here:
http://www.fordscorpio.co.uk/fanrepair.htm

Some people say they’ve managed to free it up by squirting WD 40 onto the bearings via the filter housing.

Title: Re: Cold Heater - Link with Temp gauging?
Post by Headscratcher on Feb 7^th, 2008, 11:05pm

The squeak only lasts a second or two, and I think it is associated with a change of heater blower speed, or perhaps one of the air control valves/flaps moving. The fan normally runs at the speed I would expect for the circumstances, it is just that one of the effects I have is that sometimes the airflow decreases almost to nil, even with the fan running fast. This happened before the aircon was gassed (which it badly needed) so I don't think it was icing. Also the pollen filter is new. Thanks for all the suggestions, but I'm really asking if anyone knows enough about the controls to tell me if the aircon/heater controls can affect the temperature gauging. circuit.

Title: Re: Cold Heater - Link with Temp gauging?
Post by jonnycab on Feb 8^th, 2008, 1:40am

The aircon controls do not affect the temperature guage, as the guage works from a sensor in the thermostat housing that reads the temperature of the water flowing past it in the cooling system....so nothing to do with the aircon system :)

As Snoopy suggested, have you checked that the heater matrix inlet & outlet pipes are the same hot temperature....they should be too hot to hold for more that a few seconds once the engine has warmed up.

Usually if the heater matrix is blocked or restricted then the outlet pipe will be cooler than the inlet pipe as there will be hardly any water flowing through it back to the engine block, which (in my experience) does cause a fluctuating temp guage :)

Hope this helps :)

Title: Re: Cold Heater - Link with Temp gauging?
Post by Headscratcher on Feb 8^th, 2008, 6:53am

jonnycab,

The pipes are about the same temp, but either I've got asbestos hands or they are not that hot with the coolant temp at its historically normal position. I know where the temp senders are, having changed the gauge one, however, I expect that the SATC takes coolant temp as an input signal, so I wondered whether a fault in the SATC could in turn affect the gauging circuit. However, your observation that low flow through the matrix can cause fluctuating temp is interesting. When I fushed the matrix, there was little resistance to flow, but I don't know how that would compare with a new matrix.

Title: Re: Cold Heater - Link with Temp gauging?
Post by Tompion on Feb 8^th, 2008, 10:25am

I took a few readings via OBD a while ago:
From cold the heater fan is on low, then when the coolant reaches 120F (49C) the fan speed increases (usally after about a mile on mine), once up to temp the fan speed drops back to a speed to maintain the set cabin temp.
It would appear the climate control doesn’t know if the matrix is blocked or has an air lock & will continue blowing air at the increased speed even if it’s cold air because the engine has reached the preset temp.

I don’t know if the heater fan speed drops back if the coolant temp drops below 120F.

Other readings:
Engine fans on low at 210F
Engine fans off at 202F

Title: Re: Cold Heater - Link with Temp gauging?
Post by Headscratcher on Feb 8^th, 2008, 5:17pm

Tompion,

Interesting that the fan speed is sensitive to coolant temp - that supports my theory that there is a link between coolant temp gauging and the SATC, so there is a possibility that a duff SATC affects the temp reading on the gauge. What we need is the complete system diagram

Title: Re: Cold Heater - Link with Temp gauging?
Post by scorpio_man on Feb 8^th, 2008, 5:56pm

hi there

here's the wiring diagrams, if it helps.

http://www.carsoft.ru/avtorepair/sierra_el.html

hth

Title: Re: Cold Heater - Link with Temp gauging?
Post by Headscratcher on Feb 8^th, 2008, 6:16pm

Thanks, That certainly shows a link between the SATC and the instrument panel through F16, but that seems more like a power circuit than a signal circuit.

Title: Re: Cold Heater - Link with Temp gauging?
Post by Jim on Feb 8^th, 2008, 6:36pm

Pipes should be hot. If the temperature is at normal all hose temperatures will be in equilibrium, well sort of. I would go for either air lock or blocked matrix.

Title: Re: Cold Heater - Link with Temp gauging?
Post by ren on Feb 8^th, 2008, 10:42pm

its a blocked matrix i say this because its made up
by 7 seperate u bend aluminium pipes which lead off the inlet
and back into the outlet tube seprately if you look
at a pic of a matrix you will see that the inlet/outlet
tube fixes along the edge of the matrix to allow for
the 7 tubes to be attached,and when you blast water
along the inlet tube (i call it tube b/c its more of a plastic
compound than a metal)the first pipe with the weakest
muck gets cleaned out now as we know water will always
travel the easy route so it aint going to try and unblock
pipes when it as an easy way past
theres got to be others out there with a matrix that if they
look down the inlet tube will see the 7 slots/holes
to verify the difficulty of trying a backflush whilst matrix
still fitted in car

Title: Re: Cold Heater - Link with Temp gauging?
Post by jonnycab on Feb 9^th, 2008, 2:42am

Headscratcher....you must have asbestos hands if you can hold a boiling hot matrix pipe for more than a couple of seconds }{

Seriously though, they should both be red hot. If only luke warm then it sounds like the matrix is restricted & only letting a limited flow of water through it. Also if the matrix inlet pipe is hotter at the manifold end than it is at the matrix end, then this is another sign that there is a blockage in the matrix :)

Flushing with a hose pipe may produce a good flow with little resistance, but a hose pipe with the tap turned on full produces alot more pressure than a car water pump does.

Your theory about the SATC affecting the engine temp guage I think is wrong.... it may take readings from the temp guage (don't really know), but it certainly wouldn't give any back & deffinately doesn't affect the cooling system in any way. The temp guage works purely from the sensor in the manifold, it doesn't even go via the PCM. The ECT sensor next to it performs that job :)

To put it in nutshell.......for all the climate control & heating features etc that the Scorp has....it still needs the good old fashioned tried & tested, been around for years cooling system to make it work.....& if the cooling system has a problem, then the gadgetry won't work properly :)

Remember.......It's made by Ford, not NASA ;)...... ;D

Title: Re: Cold Heater - Link with Temp gauging?
Post by Headscratcher on Feb 12^th, 2008, 11:27pm

Still no heat and it is pretty chilly going 25 miles to work. If I put blower from off to auto, the indicated temp sometimes drops in a few seconds from mid position to almost the blue sector and then recovers. If the problem is no flow through the matrix, then how come the heat is lost so quickly by turning the heater blower on? It still seems to show the symptoms of an electrical response. To answer jonnycab about asbestos hands, at the end of a 25 mile run I can hold the radiator top hose reasonably easily, and I wouldn't say the heater hoses were much cooler.

If I am to replace the matrix, what can I check out in the heater controls flaps/ motors etc whilst I'm at it ?

How much would a new SATC be, and is that easy to change?

I did see a part number for the correct matrix for a 2.3 Ultima on his site, but can't find it again.