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What causes air conditioner compressor to shut off? - Interior/Exterior/Lights/Glass/Alarms/ICE/HVAC/Other - The Lotus Forums Jump to content
mark248am

What causes air conditioner compressor to shut off?

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I've started using the cars AC this past week because the weather has gotten warm and I noticed something weird. The AC compressor would should off randomly at times and I would just get air coming out of the vents. At first I thought the compressor would disconnect at high rpms but that isn't the case since I've had the compressor shut off at lower parking speeds as well.

What are the variables that would cause the compressor to shut off and the vents to just give out uncooled air?

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Low gas pressure would be the first (and probably the easiest )one to check. 

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on a new car? cuz the compressor shuts off for a minute or two and then comes back on again. but don't know what are the variables that would do that.

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 If it’s new take it back to the dealer and tell him to fix it.

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I'm trying to figure out if this is normal first. My previous Exige was the GCC spec which had the rear AC unit behind the seats so never really noticed the fronts but now my Cup is EU spec without the rear AC so my only source of cold air are the front vents. Wanted to check with other owners if their compressor also turns off and what are the variables that cause it to.

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From the service manual, 2 scenario's:

 

1. A thermostat, using a sensor inserted into the outlet side of the evaporator finning, monitors the temperature of the refrigerated air and signals the compressor to cycle on and off in order to maintain outlet air temperature just above freezing

2.  The clutch will also be disengaged by the ECU if a loss of refrigerant is detected by the trinary switch 

 

 

 

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Golden rule about A/C In cars is they need to be run all year round prefrably once a week 

If the outside ambient is to cold run the car up to temperature and the cabin and then place on recirc and put the A/C on 

Now it's got something to chill if you don't run the compressor for a long period then the glandseal on the input shaft of the compressor looses its oil coating and its only that which stops gas loss

I've lost count how maney cars I've recharged after the ( it was working last time i used it in the summer ) 

Another thing please don't engage the A/C at high reves it does neither the compressor or the clutch any favours 

If your hot wait till the next set of lights or even dip the clutch let the reves die down then the A/C on 

Never had to recharge my old Mercedes and that was 18 Years old before it had to go because of rust but the A/C was blowing cold right till the last 

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I don't think my issue has to do with gas loss. Gas loss would mean the AC is never cold or not that cold but in my case its actually cold, just sometimes the compressor stops and the vents just give out air before the compressor comes back on again a couple of minutes later.

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iWhen the A/C Is running do the radiator cooling fans run as the compressor could be stopping on High Condensing pressure which decays when the compressor stops and allows it to start again 

But usually when on the move above day 30-40 mph this isn't a problem due to normal airflow through the car radiator 

remember the A/C Condensor is strapped to the front of the radiator and is designed to get the first cool air supply 

As for short of gas it could still be short as the compressor will run but due to insuficant charge it will cool initially untithe pressure drops then stops 

Also if the pressure is low the evaporator will tend to ice up and reduce the boiling affect and the pressure further 

When it runs with an outside temp of say 25'C And the engine at about 3K reves you should be getting air out of the vents at about 6'C or there abouts with the interior fan at high speed if it can do that then it might be a thermostats problem just nocking it off to earley 

Remember when testing the A/C give it a while to get going refrigeration effect is never instant 

Also remember most cars A/C only hold around 700grams of R134a so you only need a slight weep and it soon goes 

And they are critically charged so no extra is allowed to accomadate for losses 

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There was an ecu update (Version N), might be worth making sure your up to date as they wouldn't tell you. That update was

 apparently was to correct an AC fault of some sort.

Martin S

 

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where could i find info on the update out of curiosity?

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I guess just ask your Lotus dealer what the latest ecun update is and if its on your car. I got mine update for free but now they charge a small fee apparently.

 

Martin S

 

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On ‎10‎/‎05‎/‎2018 at 08:23, MARTIN_S said:

There was an ecu update (Version N), might be worth making sure your up to date as they wouldn't tell you. That update was

 apparently was to correct an AC fault of some sort.

Martin S

 

That was to do with an over sensitive compressor / engine speed mismatch cut out. 

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How long ago was that? cuz when I picked up my car in Jan they told me they had applied all the software updates to the car.

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I got my update about 10 months ago.

Martin S

 

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