Author Topic: Engine fans constantly on while A/C is on (Read 12796 times)

Beneeeeek · « **on:** March 23, 2024, 05:38:52 PM »

Hi everyone. I already seen similar topics but still need some advice. I just noticed that that engine fans are Ci stantly running when I'm using A/C. Before them been kicking on and off in like 20 seconds intervals but now the fans keep spinning until I manually turn them off. When switching A/C on I can hear compressor kicking in and it seem to work normally, I had system regassed and checked for leaks about 10 months ago (gas run out because of faulty valve)
Some people say that my gas level is on the level to just start the compressor and fans but not high enough to cool properly to switch the fans off with proper intervals.
What do you suggest? Is it just a case of regassing and checking the system again at the garage or you might have a different solutions?
Thanks in advance.

jazzphil · « **Reply #1 on:** March 24, 2024, 09:14:37 AM »

I have the same issue. Raised it on this forum and was told it's normal. Have had the system checked and advised all is performing as it should. I've just learned to live with it....

madasafish · « **Reply #2 on:** March 24, 2024, 09:57:04 AM »

Normal. Switch on ignition: fan on..Switch off ignition : fan off.

GBH · « **Reply #3 on:** March 25, 2024, 07:49:39 AM »

When parked at the side of the road with a cold engine and the A/C turned on I can hear and see both fans switch in and out.

I'm sure that this also happens with a hot engine - will check later this morning after a drive.

Have just got back from a four mile run (mainly in traffic) so engine is now hot and both fans are switching in and out with A/C switched on.

Lord Voltermore · « **Reply #4 on:** March 25, 2024, 10:06:37 AM »

I dont know how this will affect whether the fans start and stop due to a thermostat. But it seems logical that the aircon condenser fan would run constantly while the aircon compressor is engaged. If the cabin temperature indicates the aircon doesnt need to run constantly I would have thought it more fuel efficient to disengage the compressor (and the fan at the same time) . If it runs constantly maybe the aircon is not cooling the cabin very efficiently. Have you checked the cabin air filter?

When the compressor engages it puts more load on the engine ,which may produce more heat. The ECU may engage the engine cooling fan to overcome this extra heat, actual or anticipated. If the aircon fan and compressor are not disengaging ,for whatever reason, ,maybe the engine fan wont do so either.

A further thought, but just a theory. . If you use the aircon in the winter the system may be programmed to assume you are using it to dehumidify the cabin rather than cool it. Maybe a cold outside air temperature overrides the cabin temperature and allows it to run for longer, as it wouldnt be easy to detect how long you need dehumidifying.

Beneeeeek · « **Reply #5 on:** March 25, 2024, 03:02:32 PM »

Quote from: Lord Voltermore on March 25, 2024, 10:06:37 AM

I dont know how this will affect whether the fans start and stop due to a thermostat. But it seems logical that the aircon condenser fan would run constantly while the aircon compressor is engaged. If the cabin temperature indicates the aircon doesnt need to run constantly I would have thought it more fuel efficient to disengage the compressor (and the fan at the same time) . If it runs constantly maybe the aircon is not cooling the cabin very efficiently. Have you checked the cabin air filter?

When the compressor engages it puts more load on the engine ,which may produce more heat. The ECU may engage the engine cooling fan to overcome this extra heat, actual or anticipated. If the aircon fan and compressor are not disengaging ,for whatever reason, ,maybe the engine fan wont do so either.

A further thought, but just a theory. . If you use the aircon in the winter the system may be programmed to assume you are using it to dehumidify the cabin rather than cool it. Maybe a cold outside air temperature overrides the cabin temperature and allows it to run for longer, as it wouldnt be easy to detect how long you need dehumidifying.

Yesterday I went to kwik fit to have the system regassed, after whole procedure the fans are acting normal like it was before, so now short intervals between on and off. The guy at the garage said that I had about 100mg left in the system which is really low. There should be around 394mg when fully topped.
Last time I had air con regassed 10 months ago so he said that a little bit to fast to drop down so much. But on the other side I'm using A/C everyday and in the winter as well. The vacuum test was fine. He advised me to take it to another garage to do a UV test but I think I'll leave it for now as it is. Maybe it's just normal that because I'm using it everyday it will run out of the gas faster.

Lord Voltermore · « **Reply #6 on:** March 25, 2024, 04:05:46 PM »

I'm no expert but i would have said losing 3/4 of your gas in 10 months is a significant leak, regardless of how you use the car. I believe aircon professionals have a legal obligation to refuse to keep topping up cars if they know it has a significant leak. If it hasnt reached that stage yet it may do so soon.

Depending on how old your car is it may be worth looking into the possibility of using a leak stop additive. The professional regassing outlets dont normally use this as its not a reliable fix and there may be disadvantages so they cannot give any guarantees. But halfords sell kits,£19.99 if your gas is R134 (which it probably is) , or £29.99 if your gas is R1234 , But I believe you also have it topped up with refrigerant gas immediately afterwards, or as part of the procedure . You might also need to buy gauges and
connectors, for another £20. if you have these gauges you might be able to buy a bottle of refrigerant gas that may be enough to do 2 -3 refills. But there may be other more suitable kits on the market. But I'd advise you to research the pros and cons thoroughly and its at your own risk. And it might not work.