Technical Peculiar A/C compression issue Palio 1.6

[vijaycool]

Hi Guys,
I have this issue for the past 1 year. Now I must fix this issue as its killing the milage. My car is not Auto A/C type. When I turned on the A/C after 15 secs high speed fan comes on and it runs for 10 secs then gets turned off. Wait for another 15 secs it will kick in. Initially I thought the refrigerant was low and asked the mechanic to add some gas so that pressure switch will keep the fan running. But even after adding gas the pressure switch repeatedly clicking off after every 15 secs of operation. I have even replaced with another switch still the issue persist. The A/C compressor is not cut. What we have found is high speed fan is controlled by the pressure A/C pressure switch and compressor is controlled by the thermostat. As the pressure drops 2nd speed fan cuts but since the thermostat cutoff point is not reached the compressor continues to run. I was inspecting the high pressure pipe and it looks like the pipe is very hot to touch when the fan is running. When the fan turns off the pipe is cold. I can say the compression of the refrigerant happening intermittently so when the compression is high the temperature and pressure rises causing the pressure switch to turn on the fan. Suddenly the pressure drops causing the pipe to cool and due to insufficient pressure the pressure switch unlocks causing the fan to stop. Cooling is also not great as the compression is happening intermittently. Since the fan is not running at a stretch the temp needs stays just above 1/2 mark. A/C mechanic is confused and couldnt able to provide any solution? Does this mean the A/C compressor is kaput. Please advice.

Regards,
Vijay

 

[Most Easterly Pandas]

TBH, that actually sounds normal - how our Fiats with AC have always operated.

 

[vijaycool]

Actually thats not normal. Since the compressor is running the pressure switch should keep in closed position which makes the fan to run continuously. Another A/C mechanic suggests that "loading valve" (I dont know what) is failed causes this uneven pressure issue.

 

[Most Easterly Pandas]

Tbh your post was a bit of info over load. What I got is that the fan comes on for about 15-20 sec every 15-20 sec and that the compressor clicks in and out like this also. Is that correct

 

[Peter Pick-Up]

My suggestion: maybe find another A/C mechanic, who knows what he's doing....!!

www.autoacforum.com

 

[Peter Pick-Up]

Actually thats not normal. Since the compressor is running the pressure switch should keep in closed position which makes the fan to run continuously. Another A/C mechanic suggests that "loading valve" (I dont know what) is failed causes this uneven pressure issue.

This is NOT normal, the fan shouldn't run all the time with the A/C on....!!
It is supposed to "cycle"...!!

 

[Most Easterly Pandas]

This is NOT normal, the fan shouldn't run all the time with the A/C on....!!
It is supposed to "cycle"...!!

Glad you've cleared that up Peter, TBH when I first got my Stilo, I thought it was suppose to be constant, but soon learnt otherwise, and as said our other Fiats with AC do the same, so it must be right.

 

[vijaycool]

I have checked atleast some dozen of palio's none of the car exhibit this issue. Here Weather is very hot 38~43C. It will take atleast 10 mins to achieve the grill temperature to 2.5C (cut off point). The only possible way to cycle the fan is the thermostat cutting in frequently which cuts A/C clutch to disengage resulting drop in pressure. As I mentioned earlier this should take atleast 10~15mins to achieve. But right from the starting the fan cycles to On-Off. I must visit other competent A/C mechanic and will keep posted.