Problems with air condition

[SamoL]

Hi!

My problems with air condition are not over. At the end of the year the compressor died. I had it refabricated and now it gets really loud from time to time. So I took it back to the AC service and they've cleaned the radiator as they said the cooling of the AC fluid was not sufficient and the pressure in the AC system gets too high. The situation might be better now but I can still hear the compressor when the AC is on for some time.
In the AC service they claim, that the viscous coupling of the fan might be weak (as they were able to stop the fan with a hand - I didn't try it as I like my fingers too much). Is this possible (and I don't mean to stop the fan with a hand)? What are the signs of a weak viscous coupling? Should the fan run when I start the car (and the car is cold - not running over night)? The engine was never too hot, but they've said it is normal for diesel engines, as they don't need that much cooling ??!!?!

Regards
Samo

 

[100 TD]

The viscous fan coupling on my old Nissan Patrol used to take off like a jet engine winding up, so did a mates LC, but this was years ago and I have not heard my TD do it but it should. (windows are always up,screaming kids and stereo, cant' hear a lot)

Try this
Run the engine up to operating temperature and set a lump of wood on the throttle so it runs at 2000 rpm. Sit, wait, and listen, the fan will be turning, but slower than the engine, when the viscous coupling gets hot enough it will kick in and and start driving the fan 1:1 with engine revs, you will hear it come in and make a roar.

An electric fan on the condenser would help, but the noise should not be there.

 

[SamoL]

I've checked it - and yes it roars. When the engine is hot it rorars when the engine picks up the revs when the AC compressor is running (with the car parked and in the neutral).

The compressor makes a high freq sound (like screaming) at high engine rpm (the easiest way to hear it is if you run the engine to 3000 rpm in neutral and then lift your right foot ).

Can you try it and tell me if you hear any differences with AC on/off?

Thanx
Samo

 

[Campfire]

There can be a lot more to the high pressure than the viscous fan. Did they change out the receiver dryer when they rebuilt your compessor? A/C compresssors can spit lots of junk downstream to form clogs and restrictions. Restrictions cause higher pressures, if your viscous fan was going out you should be seeing overheating problems also. Good luck

 

[ScrapIron]

Viscous drive fan & a/c

sir, you should be able to stop the viscous fan with about anything unless it is fully engaged, and that is only when there is not sufficient air flowing through the radiator to cool the fluid. at all other times, the fan freewheels, as is its designed function. If you don't see fluid leaks,or stains from fluid leaks around the drive side of the fanhub seal, the fan, as a general rule,is fine. There are certainly exceptions to this,as we all know. I would guess that as another member said, that your service people did not flush the system & change out the filter and/or drier/ reciever. Another possibility is that the system was not vacuumed sufficently and left air entrained, which causes water, which freezes in the valves, etc, & pressures go up, as the compressor is pumping against a blockage, so it makes a bunch of noise. Personally, I always install a suction side filter after any compressor work, and have found over the years to be cheap insurance.

 

[SamoL]

Thanx. I'll try to get a second openion next week. I think they didn't fix the compressor right and they certainly didn't change the filter. No wonder it doesn't work as it should.

Regards
Samo