AC Compressor

[melbs]

Ok, on my third AC compressor in 6 years.

First compressor died 4 months ago (just suddenly no AC one day)
Second compressor died a month ago (just suddenly no AC one day)
Third compressor is acting up again today (see problem below)

Whenever my car is idling the A/C compressor runs fine, but when I rev to about 2000 rpm, my compressor stops, tries to run again and stops after a second or two, then repeats the cycle again.

Compressor cannot seem to engage properly.

What could be wrong?

My compressor is new, and was just installed yesterday. It cannot bad luck be that the compressor is defective yet again!

Either the installation was wrong or something else is causing this fault electronically or mechanically (belt runs faster as you rev higher)

Experts, need your help

 

[cj10jeeper]

Have you cheched the compressors that they were broken and not an issue in the control systems?

I'd be looking at the engagement / clutch mechanism and not the compressor itself as it seems unlikely for 3 to go in 4 months assuming nothing is seriously untoward in the system (which I doubt).

If it were fitted for you then why not ask the fitter what is wrong and to stop fitting pumps and identify the problem?

 

[melbs]

the first one, they said its compressor failing. won't engage at all, after a very loud grinding sound just didn't work after.

the second one, they said its the clutch mechanism. isn't the clutch mechanism part of the compressor?

yup asked this the very first time it occurred. they said bmw compressors doesn't last long as compressors installed in japanese cars which ironically is a japanese brand (calsonic). 6 years they said is just about normal.

second time, they have no idea what caused it, but simply said compressor was faulty, so they changed it under warranty.

now on my third, have yet to inform them of the instance as its xmas break here. for sure will demand a proper diagnostic of what happened to the 2nd and now this compressor.


just an update:
let the car cool down, did city driving for an hour and AC system so far is working. compressor engages only once and at start up of AC

remembering:
the second compressor conked out while i was on a 3 hour trip with speeds of 200 plus kph and half of the travel time in bumper to bumper traffic

this third compressor conked out while i was on a road trip again, with speeds of sustained 140 to 160 kph all the way for about an hour, park under the sun, get to the car after an hour and then it went kaput.

something similar would be sustained high rpm and speeds. possibility of compressor overheating because of this?

 

[Gorbash12346]

you do know that the compressor is designed to cut in and out during heavy throttle loads to free up power? and also that the compressor is meant to run in short bursts even when it's set to maximum cold setting all it needs to do is regulate itself and keep the temps within a certain window

if this does not answer your question then i'd be looking into what they are filling the air-con system with shoild be R134A and if it's not it can cause issues. also they NEED!! to add PAG oil to the air-con system after draining the old oil out of the system (if your pump failed internally i.e. not the clutch, then the system may be contaminated.

As for the air-con compressors not lasting any time... RUBBISH!!!
i work in a main bmw dealership and air-con pump failures are extremely rare

as for japanese ones lasting longer my mums EP2 civic sports failed after 45k miles....

hope this helps

 

[cj10jeeper]

With all due respect it sounds like the garage doing the work are not really sure of what they are doing. Just swapping pumps without really knowing what went wrong and why, making claims about life expectancy, etc.

I'd go back get them to do it properly and pick up on Gorbash's good information on fluids.

Seems to me the high speed runs are just bringing to the fore quickly a problem that not being fixed by just swappping in and out pumps.

 

[Anonymous]

you do know that the compressor is designed to cut in and out during heavy throttle loads to free up power? and also that the compressor is meant to run in short bursts even when it's set to maximum cold setting all it needs to do is regulate itself and keep the temps within a certain window

if this does not answer your question then i'd be looking into what they are filling the air-con system with shoild be R134A and if it's not it can cause issues. also they NEED!! to add PAG oil to the air-con system after draining the old oil out of the system (if your pump failed internally i.e. not the clutch, then the system may be contaminated.

As for the air-con compressors not lasting any time... RUBBISH!!!
i work in a main bmw dealership and air-con pump failures are extremely rare

as for japanese ones lasting longer my mums EP2 civic sports failed after 45k miles....

hope this helps

Good info

 

[melbs]

thanks guys for your inputs, yes the bmw stealership doesn't seem to know what its doing as always.

i will ask them about your insights Gorbash, thanks for the sharing.

just added more observations:

1. when car is parked outside (today whole day) 33.5 degrees Celsius on the obc, the compressor is not engaging fully again, you could hear and feel it engage a couple of seconds then stops then tries to engage again, then repeats the cycle again and again. the vent flows cool air when it runs a few seconds and then no cool when its not running initially, until no cool air totally as compressor tries to run/cut/run/cut.

2. took out the car again tonight 27.5 degrees Celsius on the obc, the compressor engaged flawlessly upon initial start up no loss of coolness whatsoever. parked and rev'd it similarly like the other day and all rpm rounded off to the 1000 until almost redline and compressor kept on spinning the whole time with cool air.

I noticed also that the aux fan is running louder than before everytime the AC is on, I know that the aux fan should run when the AC is turned on but this time its like its set at maximum speed.

Should i check condition of thermostat perhaps?

I'm trying to have the car checked for fault codes in sensors and other electronic bits by an independent soon and also an independent AC shop to get freon readings, etc before i storm the stealers.

On the previous occasion that the compressor did not engage, i parked the car under the sun as well, but the very first one was plainly a fast run.

 

[melbs]

Ok did another run today

- car parked in garage
- cool air upon start up
- 2 hour non stop drive / highway / speeds up to 120 kph only
- cool air all throughout the drive

decided to drive aggressively by flooring and reaching 180 kph then back down to 100 kph then back up to 180 kph

guess what, after a 5 to 10 minute period no more cool air, i could hear the grinding sound of the compressor trying to engage again and again.

shut down and garaged the vehicle
- after an hour / start up / cool air once again.

i can sense this is definitely temperature related. whether car soaked under the sun the whole day or car's engine running hot, the compressor fails to engage properly.

took a video of my compressor trying to continuously engage. will post the link in a bit

 

[melbs]

http://www.youtube.com/watch?v=nyr9K1-sli0

 

[Gorbash12346]

possibly a problem with the cooling fan for the air-con radiator as you say it ran much louder than before when you got cool air all the time... either that or whatever temperature switch it operates on. when i get back from the states i'll have a look and see what's on the circuit

do you have basic air-con or climate control?

 

[melbs]

i have the climate control

 

[melbs]

A complete flushing and refilling of the refrigerant solved the problem.