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AC cut out switch info.

Dave2000

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spain
Looking for the switch cut out settings, FSM shows the switch but not the rating.

Petrol versions according to our friends across the pond have them rated at as near as you like 107°C, anyone know if the diesel switch is the same part number or temp?

Regards

Dave
 
I’m interested in this because my AC works fine when the engine is cold but when it’s at running temp (and there’s no indication that the engine is running hotter than it should) the AC stops working, or at best it is barely cool, not cold.

It’s as though something is switching off, but I’m sure the AC is still cycling on & off, although not cooling like it should.

I had it regassed last summer and I dont mind doing it again this year, it’s only about £18 a time, here.
 
Hi Clive, mine was working fine when I took the car off the road for preventative maintenance.........thats buggered it!

I use an electric fan to cool my engine, and am presently trying to fine tune my overheating warning system. Your right the switch does drop out the AC function if the engine temperature is too high.

If I understand the wiring diagram, the switch is normally closed when working ok and temps are normal? You should be able to pull the plug off and see if it makes any difference to your AC cutting in and out, and of course if we can find out the temperature it operates at I can finish my project, and you can test yours with a MM and immersing in oil.

EDIT: Should have added 'jump the plug, if the switch is faulty your AC should now stay on'.

Regards

Dave
 
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There's a strain on the engine when AC pump is driven so it's cut out when engine temp is high so to bring the engine temperature down ??
 
There's a strain on the engine when AC pump is driven so it's cut out when engine temp is high so to bring the engine temperature down ??
And to have cooler air available for the radiator with no heat being lost by the condenser.

I’ve no idea on the Cut in and Cut out temps of the switch Dave. I guess you’re thinking of linking into that switch to give an overheat warning? Would you not be better off with a simple digital thermostat? Amazon have some at under £20.

Clive, I suspect your AC system has moisture in it and is plugging up the orifice :shock: .
 
image.jpg
When I installed an AC unit from a hzj78 into my hzj75, I bridged the switch to get the AC working. I guess the 80 won't be very different.
 
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All a bit beyond my small brain I’m afraid...

Ill see if i can get mine vacced this year and see how it goes. I know my 1HZ isn’t overheating, that’s why i thought it may be a faulty switch...
 
I have a digital temp gauge with the sensor under one of the bolts on the block where the coolant leaves towards the rad. Had the car up to 112c towing a big trailer in the NW of Western Australia when the outside temp was 46c, air con was on all the time and didn't trip the cut out. Its a 1HD-FT
 
Nice one Wout. :) Does it give the location of the switch?
 
Apologies all, I normally get an alert when someone replies to a thread I am posting on, nothing on this one?

Anyway, thanks to all for your contributions and to clarify, the switch detects higher temperatures than considered OK by Mr T. As per @StarCruiser the AC is cut out to prevent it loading the condenser with heat, this would added to the engine cooling radiator, and given the extra work the AC compressor adds as per @frank rabbets comments this too may help.

So story time, a couple of years back I converted the strip of plain plastic (mines manual) between the speedometer and rev counter to hold a row of LED's, these would convey extra information about what was going on under the bonnet. First attempt looked crap, it worked but for an OCD person such as I am, simply not good enough.

I drew up a design to be sent to a screen printer, in the meantime had asked @karl webster send me the centre piece from an automatic transmission dashboard, this normally told the driver of the gear range selected.

maxresdefault.jpg



So I had graphics added to a piece of 'dead fronted' material, so nothing is shown as per the OE dash when not illuminated.

Dash insert.png



This was integrated with my electric engine cooling fan, it showed different speeds, loss of coolant, loss of oil pressure (which the stock 80 only has a gauge) not noticed until it is too late, and of course other 'stuff'.

Status indicator.JPG


I am trying to get the overheat warning to work accurately enough to not trigger false alarms, by having the sensor cut out temperature, I can extrapolate the temperature switch needed to trigger the LED and activate the buzzer paralleled with low oil pressure and coolant loss indicators.

I had considered the AC switch but was not quite sure if when open circuit there would be a live potential when not earthed? If yes this would feed back to my LED's and they do not like that. :icon-cry:

Also in the interest of future fault finding, I try to keep wiring mods as isolated from OE wiring where possible, so the switch is to be independent.

The post from @SeaJay mentions AC still working @112 C°, I am thinking this a good ball park figure in fact, would be happy to switch off the AC manually at that temp however, our friends across the pond AC switch on their petrol version cuts at 107 C°.

EDIT: I have just seen @Firewout's post, how I missed that in the FSM I don't know, thank you for that clarification mate, you are in a beer credit! :clap:

So I am now working on finding a sensor, many thanks again.

Regards

Dave
 
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I’m interested in this because my AC works fine when the engine is cold but when it’s at running temp (and there’s no indication that the engine is running hotter than it should) the AC stops working, or at best it is barely cool, not cold.

It’s as though something is switching off, but I’m sure the AC is still cycling on & off, although not cooling like it should.

I had it regassed last summer and I dont mind doing it again this year, it’s only about £18 a time, here.


Check your heater valve is closing properly Clive, it is adjustable and a common fault. Even when closed and getting old the valve does not always seal shut properly, when closed the pipe exiting the valve should remain cold, your symptoms match this problem exactly.

Regards

Dave
 
Check your heater valve is closing properly Clive, it is adjustable and a common fault. Even when closed and getting old the valve does not always seal shut properly, when closed the pipe exiting the valve should remain cold, your symptoms match this problem exactly.

Regards

Dave

Good call Dave, I’ll give that a look at, its simple enough even for me to check, cheers :thumbup:
 
Hi guys,
I'm on the road in Azerbaijan at the moment and the AC has decided to retire (again!)
I am suspecting an electric fault as jumping the compressor produces cold air but I'm having trouble locating the high temperature sensor on the 1hd-t to short it out as the first likely culprit. There is a likely looking candidate down by the oil filter but confirmation before messing with it would be appreciated. Next I'll be looking for the clutch relay! All suggestions welcomed as it's 30 degrees here.
John
 
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