300Tdi A/C Compressor - How to test?

[bebes2k]

Hi there,

A few weeks ago I went to turn on the air con in my 130 300Tdi ute and unfortunately it blew warm air instead of the usual ice cold. I've had the vehicle for about a year but I haven't put many kms on it, especially recently.

When I purchased the ute it didn't have functioning air conditioning so I had it inspected and re-gassed about 12 months ago. At the time there was an electrical issue which didn't allow the compressor to probably engage. So the system was re-gassed and passed the checks with the UV dye that was inserted as well and cooled very well when it was hot-wired. A few weeks later I cleaned the contacts in the battery box and had fully functioning air conditioning which was great!

This time around it doesn't look that easy although I am keen to hear if there is anything else I can do to test the compressor before I send it in to have it properly diagnosed.

I have tested the system best I can which included changing the temp dial and listening for the clutch to engage-disengage which I can hear working. I connected a test light to the compressor which also turned on and off. I looked at the sight glass and it looked 'normal' with the yellow dye still visible. Am I right that the pressure switch is designed to prevent the compressor running when the system has evacuated so if the clutch is being told to engage then there must be sufficient pressure in the system right?

When the system has been running, but not cooling, the compressor got very warm to the touch. Before when the system was working one pipe going to the compressor was very hot and the other was very cold. This time around one pipe was very hot and the other was room temp.

Even though I can hear the clutch moving is there a chance that it's not engaging properly? Any thoughts? My train of thought has me thinking that the compressor has a fault - is there a way to test to confirm? Can it be rebuilt or is this a replace only exercise?

Your help is greatly appreciated and I have read most of the other articles on this issue to no avail.

Cheers, Bill.

[rick130]

Hi there,


[snip]
When the system has been running, but not cooling, the compressor got very warm to the touch. Before when the system was working one pipe going to the compressor was very hot and the other was very cold. This time around one pipe was very hot and the other was room temp.

[snip]

Cheers, Bill.

Time for some gauges on the system

The suction line should be cold and sweaty (depending on ambient humidity)

You may have a system blockage (blocked drier, faulty TX valve) or just be short of refrigerant.

[Marshall]

I agree with Rick, put some gauges on, your local A/C guy can do this in a snap and won't usually charge
I would say the TX valve is blocked, you seem to have checked the rest. a new one costs around $64, then about 2 hours to fit, ($220) and a re-gas ($150), all up about $400.

[bebes2k]

Thanks for your comments, it's unfortunate to have to call an expert to fix the problem as I always prefer to investigate, diagnose and fix problems myself but I guess that's why they're called experts!

At least your help has pointed in the most plausible direction so that I'm prepared for the cost of the repair.

Cheers, Bill.

[bee utey]

Thanks for your comments, it's unfortunate to have to call an expert to fix the problem as I always prefer to investigate, diagnose and fix problems myself but I guess that's why they're called experts!

At least your help has pointed in the most plausible direction so that I'm prepared for the cost of the repair.

Cheers, Bill.

Purchase a pressure gauge from ebay:

SINGLE GAUGE MANIFOLD 134a,407c,R22 REF/AIR CON (eBay item 290533892973 end time 15-Mar-11 09:22:55 AEDST) : Home Appliances

or this set which comes with R134 adaptors:

Air Conditioning & Refrigeration Gauges Manifold & Hose (eBay item 190500557633 end time 17-Feb-11 20:50:32 AEDST) : Cars, Bikes, Boats

[rick130]

Purchase a pressure gauge from ebay:

SINGLE GAUGE MANIFOLD 134a,407c,R22 REF/AIR CON (eBay item 290533892973 end time 15-Mar-11 09:22:55 AEDST) : Home Appliances

or this set which comes with R134 adaptors:

Air Conditioning & Refrigeration Gauges Manifold & Hose (eBay item 190500557633 end time 17-Feb-11 20:50:32 AEDST) : Cars, Bikes, Boats

But you still have to know what it's telling you, and you can't purchase refrigerant unless you have an ARC Trading Authorisation

Gone are the days of buying a little disposable can like you still can in the US (They can buy them from Wal-Mart )