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Discussion Starter · #1 ·
Hi all this is my first time here so please be gentle with me. My 45 hatch has a problem with the air conditioning all help greately recieved. I bought this car just after the Germans pulled the plug and the new management took over it is 5 years old now. My problem is there is no power going through the red lead to the air con clutch ? drive under the Alternater. I know this because the thing works fine if i connect it up directly to the cigar lighter. The fuse is fine and the air con light comes on when the fan is running in the car. Is there another fuse somewhere i should be looking for ?, or does the electricity supply come via some other route than, heater fan, air con switch. As i said everthing works ok when i connect directly. Is this a comon problem, a fault in the wiring loom perhaps. Thanks in advance for all help.
Oh i have had it looked at by my rover dealer, all they suggested was to replace the unit itself which i thought daft when i know it works. Hmmm makes me think it is something simple and they just want some more cash out of me.
 
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It is probably low coolant pressure. If some of the gas has escaped, the pressure may be low enough to cause the low pressure safety switch to activate in order to cut the power to the compressor and save it from damage. A top up of the refrigerant will probably do the trick.

Do you use the system regularly throughout the winter? If not, you should because the refrigerant in the system stops the seals from drying out and therefore allowing gas to escape.
 

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Discussion Starter · #3 ·
Hi thanks for the fast reply. I did get the coolant checked before i wired it up direct though and it did not need any topping up.
 

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It could be a couple of things.

Have you checked all the fuses??

The ECU will not energise the AC if it thinks there is too little gas in the system, or if it thinks the engine is too hot!! Could have a bad engine temp input into ECU.

Could be a bad relay also, or this may be within a multi function unit.
 

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Discussion Starter · #5 ·
Yes i have checked all the fuses thanks. The fault started when i had not used the air con for a few weeks. So you think something is stopping the power on purpose.
 

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Not sure, defo need to check the pressure is in the system.

There is also a "trinary" switch which monitors AC system pressure. Should the pressure be too low (not enough AC gas in system), the system will not cut the compressor in and should the pressure be too high (system problem) it will not cut it in either to stop it blowing up.

Something else that will cut out the system is the ICE sensor in the evaporator. This detects ICE on the evaporator fins and shuts thr system down - I think this is unlikely!!

Actually, I have just had a brain wave:

If it is an issue such as a bad fuse/relay, or something on the "output" side of the curcuit, the idle on the car will rise when you turn on the AC. The ECU raises the idle a little before it engages the compressor so the car does not vibrate/engine stall.

If, when you are pressing the AC button, the idle does not move at all, then it means the ECU is not asking the AC to come in, not raising the idle and not asking the compressor to cut in - this could be due to - thinks engine temp is too hot, thinks there is not enough gas in system, think AC system pressure is too high.

I reckon your trinary switch could be busted, or your engine coolant temperature sensor is saying the engine is overheating.

HTH
 

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Discussion Starter · #7 ·
Ok thanks for that i will check out this switch if i can and the idle speed. This will have to be tomorrow of course. Where can i find this switch please. Once again thanks for the help. I only have an old Hayes manual given to me by a friend i have never been able to find one for my 45
 

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I don't suppose we know what happened do we? I have a similar problem, and although I haven't done anything about it for a couple of years, at the time of the fault I had an aircon engineer check the gas, and my local garage could persuade the compressor to kick in by powering it externally, but it didn't work on the button. They said it might take a long time to find the fault so they stopped to save me an unwelcome bill.

John
 
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