Advice needed regarding ac problems in car

Advice needed regarding ac problems in car

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klaudmjj

Original Poster:

96 posts

16 months

Wednesday 9th June
quotequote all
Hi all, I need some advice regarding the ac system in my car.
Own a ford fiesta mk6 2007 1.4

As the weather got hotter I started to use my ac a lot more, I noticed a strange clicking noise coming from the AC compressor and I've never heard that before. Every 5-6 seconds the AC clutch disengages and after 5-6 seconds it engages again.

I know that compressors, in general, don't run all the time but I know that they shouldn't turn on and off every 5 seconds.
Now, the temperature of the AC is about 10c, measured with a crappy fridge thermometer.
I got my car's ac regassed today but I'm not convinced they have done it correctly, they had the special machine to do it, pulled a vacuum for about 20 minutes and then started to recharge my AC, however, they did not turn my car on while doing it, should they have turned the car on and the car's ac while refilling?

Anyways, after they refilled it, the AC was still clicking on and off every 5 seconds, this time I got a meat thermometer, shoved it down my air vents, turned the ac on, fan setting 1, all the vents open, left it for about 10 minutes and it was reading about 9-10c (48-50f). I've read online that the AC system should be about 5-7c (41-44f)

Didn't have much time today, but my first steps would to take it back to them and get it regassed again.
Any advice, comments would be greatly appreciated.

klaudmjj

Original Poster:

96 posts

16 months

Wednesday 9th June
quotequote all
Here is a visual representation of whats happening.
https://www.youtube.com/watch?v=rlHPFMSn9UA

Lincsls1

2,079 posts

107 months

Wednesday 9th June
quotequote all
klaudmjj said:
I got my car's ac regassed today but I'm not convinced they have done it correctly, they had the special machine to do it, pulled a vacuum for about 20 minutes and then started to recharge my AC, however, they did not turn my car on while doing it, should they have turned the car on and the car's ac while refilling?

No, the engine and a/c should be off whilst re-gassing the system.

Lincsls1

2,079 posts

107 months

Wednesday 9th June
quotequote all
I also think the temperature you're achieving is quite acceptable given that the car is stationary so will have some engine heat soak AND the car is far from new so may have lost a little performance AND its been a rather hot day.

klaudmjj

Original Poster:

96 posts

16 months

Wednesday 9th June
quotequote all
Lincsls1 said:
No, the engine and a/c should be off whilst re-gassing the system.
Oh right, just saw a bunch of videos with the engine and ac actually being on while they recharge it.

Lincsls1

2,079 posts

107 months

Wednesday 9th June
quotequote all
klaudmjj said:
Oh right, just saw a bunch of videos with the engine and ac actually being on while they recharge it.
Weird. I have never seen my cars running whilst being re-gassed over the years. Funnily enough had my Astra re-gassed yesterday (working perfectly now) and it was 100% off whilst being done.
Your issue sounds more electrical than mechanical.


Edited by Lincsls1 on Wednesday 9th June 19:57

klaudmjj

Original Poster:

96 posts

16 months

Wednesday 9th June
quotequote all
Lincsls1 said:
Weird. I have never seen my cars running whilst being re-gassed over the years. Funnily enough had my Astra re-gassed yesterday (working perfectly now) and it was 100% off whilst been done.
Your issue sounds more electrically than mechanically.
This is the video I watched: https://www.youtube.com/watch?v=Pdq8JAlct6s
He did it at home but I'm assuming its because he used a can, and not an actual machine.

Still, never had this issue before, would like to know what is causing the clicking because it drives me crazy, and if a large repair bill is avoidable with something simple, I'd rather do something simple.

Lincsls1

2,079 posts

107 months

Wednesday 9th June
quotequote all
The compressor will be clicking on and off because it is either been told (not a compressor clutch issue) or the compressor clutch could be faulty, maybe going open circuit after a few seconds then normal again - doubt it though.
You might try the replacing the a/c relay, it could be dropping out, there is probably an identical one in your fuse box feeding a different system you could 'borrow' for a few minutes to try it.
Otherwise guessing over the internet is generally futile and I would take it to a garage that can diagnose and repair a/c.
The good news is your system seems to hold gas, many older cars have a hole it the system somewhere and owners aren't prepared to pay the repair cost.

klaudmjj

Original Poster:

96 posts

16 months

Wednesday 9th June
quotequote all
Lincsls1 said:
The compressor will be clicking on and off because it is either been told (not a compressor clutch issue) or the compressor clutch could be faulty, maybe going open circuit after a few seconds then normal again - doubt it though.
You might try the replacing the a/c relay, it could be dropping out, there is probably an identical one in your fuse box feeding a different system you could 'borrow' for a few minutes to try it.
Otherwise guessing over the internet is generally futile and I would take it to a garage that can diagnose and repair a/c.
The good news is your system seems to hold gas, many older cars have a hole it the system somewhere and owners aren't prepared to pay the repair cost.
Done, and bad news, tried looking for the relay under the glovebox, it wasn't there, so checked by the battery, found it, there was only one relay and that was for the ac as when I unplugged it and tried the ac it wouldn't turn on at all.
Swapped it for the relay controlling my auto lamps, which was under the glovebox, it had the same amps, and the same circuit drawing on the relay.
It was still clicking on and off with the donor relay.

Bollycerb

422 posts

133 months

Wednesday 9th June
quotequote all
Overcharged with gas perhaps - so pressure builds up too quickly before full cooling effect takes place. This causes the trinary switch to cut power to the compressor hence the rapid cycling. Of course it could be the trinary switch itself that is faulty....
Its been a long time since i last worked in car ac so my memory is at best hazy ! I'm sure someone more knowledgeable may be along to correct me...

Also - there are two methods of regassing; by liquid or by gas. If by liquid, this is faster and performed with the engine off , or if by gas, you run the engine so the compressor draws in the gas from the bottle...

Edited by Bollycerb on Wednesday 9th June 21:24

klaudmjj

Original Poster:

96 posts

16 months

Wednesday 9th June
quotequote all
Bollycerb said:
Overcharged with gas perhaps - so pressure builds up too quickly before full cooling effect takes place. This causes the trinary switch to cut power to the compressor hence the rapid cycling. Of course it could be the trinary switch itself that is faulty....
Its been a long time since i last worked in car ac so my memory is at best hazy ! I'm sure someone more knowledgeable may be along to correct me...
I know all systems are different, but do you happen to know what the pressure should be or what it roughly should be?

Bollycerb

422 posts

133 months

Wednesday 9th June
quotequote all
Cant say what the pressure sgould be. A set of gauges attached to low and high presssure ports should show pointers at equilibrium whilst the compressor is running.
The level of gas varies between cars , theres normally a sticker under the bonnet stating how many grammes of gas to use .

scottyp123

2,554 posts

23 months

Sunday 13th June
quotequote all
Bypass the pressure switch and see what it does.