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Gary, Australia Car Mechanic
Category: Australia Car
Satisfied Customers: 1007
Experience:  Senior Technician
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I have a holden astra TS 1999. I fitted a new radiator but

Customer Question

i have a holden astra TS 1999. I fitted a new radiator but when are start up (after filling) the engine warning light and I assume the radiator warning light comes on and both fans come on like the engine thinks its hot. I thought I could perhaps check the water temp sensor but I cant find it.
Submitted: 9 months ago.
Category: Australia Car
Expert:  Gary replied 9 months ago.

Hello Alan,

Are you sure the system has been bled up?

Are the switches connected on the bottom of the radiator?

I've worked on TS Astra since they were new.


Customer: replied 9 months ago.
1. How do I bleed the system. On a youtube video they just filled up then revved the engine a little and the air supposedly bubbled out.
2. I dont remember any plugs when I pulled out the old one and when I inspect it carefully I cant see anywhere a plug would go.
Expert:  Gary replied 9 months ago.

Hi Alan,

Did you have the heater on hot, fan speed 1 so you feel the warm heater from the heater?

Does your radiator have the bleed tap on the top of the RH tank?

If not, then run the engine with the heater on once it has warmed up a bit, at 2000 rpm for about 2 minutes while watching the temp gauge and the coolant level.

Keep the level up in the header tank, and monitor the fluid and air on the top "bleed hose" on the tank.

That hose should always have flow occurring while the engine is running.

Can you tell me whether yours has a cooling module, which is mounted vertically, behind the LH bumper bar, under the headlight etc?

You can see it lying on your back under the front bar.


Customer: replied 8 months ago.
Sorry I didnt get back sooner I had to go away for the day.
The I did as suggested and there appears to be no air in the system and the heater blows hot but the fans stay on and the temp gauge dosent move.I found a couple of stray plugs (electric0 but these look like spares fo extra light or horn.
Expert:  Gary replied 8 months ago.

Hi Alan,

Was the car operating normally prior to the radiator change?

The strays underneath are for second horn and foglights if not fitted.

If the system is bled up full now, there is an electrical issue.

We now need tech2 to look at ECM and cooling module data.

Can you see the cooling module under the LHF as I described above?


Customer: replied 8 months ago.
The car was operating normally except the air-con wasnt 'clicking in'. the aircon gas was ok and I changed the air -con clutch coil but as yet dosnt seem to be power to this.
I did check for a cooling module expecting some sort of tank but now I look and see a 'black box' is that it?
Expert:  Gary replied 8 months ago.

Hi Alan,

I normally substitute a test lamp across the compressor connector with the A/C on.

If the lamp is it, the compressor clutch is open circuit.

This happens on a majority of cases.

The ECM is generally the next cause for no A/C.

Are you quite sure it has the right weight of gas?

It will not work if that is the case.

Yes, the black box you see under the front is the cooling module.

Because yours has this module, there could be a problem here that is the cause of BOTH of your problems.

Not all Astras have a cooling module.

Now you need a TECH2 diagnosis from a Holden dealer to see what the cooling module is doing.

Has the car had any impact damage in the LHF?


Customer: replied 8 months ago.
Some history: when the air-con stopped working I thought perhaps it needed gas. I took it to an air-con guy and he said that there was plenty of gas but Astras have a weakness where the fuse blows on the clutch coil. I took out the coil and using a multimeter this showed continuity. I then put 12v on it with it inside the pulley expecting a magnet but no go. I then took the coil to the garage to double check it was told it was faulty. I then hooked the mulimeter on to the wires to the coil from the switch, turned the air -con expecting to see 12v but no go. I suppose the next step is TECH2 diagnosis.As far as we know there has been no impact damage on the LHF
Expert:  Gary replied 8 months ago.

Hi Alan,

Another thing I have seen is clutch coil failure from a partly seizing compressor, overheats the coil.

I had a customers car that had a coil 2 weeks prior by another tech, I pulled the coil and it was burnt out.

The compressor took more effort to turn than normal and was lumpy, so I flushed the system, replaced the compressor and the drier/filter.

TECH2 diagnosis is the next step.

I hope my advice has been of assistance to you.

Kind regards


Customer: replied 8 months ago.
how do I know if the coil is burnt out; shouldnt the thermal fuse go first . The old coil still showed continuity.
Expert:  Gary replied 8 months ago.

Yes, normally the fuse would go first.

That one I mentioned failed from the heat conducted from the seizing pump.

Something in the 2-5 ohm range would be applicable to a magnetic clutch.

You have a few faults here, did they all happen at once. otr different times?


Customer: replied 8 months ago.
I have taken it to a garage to get the TECH2 diag
Expert:  Gary replied 8 months ago.

Ok, I'll leave it with you until you get some TECH2 diagnosis.


Customer: replied 8 months ago.
The 'temp gauge not working' and the fans coming on straight away was because the plug to the sensor was dislodged (cracked).The A/C not powering up was because the module was damaged (the techo couldnt 'talk' to it) perhaps water ingress.The temp gauge and fans are now working and I have ordered a 2nd hand module to install and then all should be oK.
Expert:  Gary replied 8 months ago.

Hi Alan,

Yes the cooling module is prone to water even with weatherproof seals on the coneectors.

Odd for the coolant temp sensor connector to be damaged, but anything is possible.

Good to hear you are sorted.