'98 300tdi air conditioner question

[Andy130]

hi guys, on my recent drive from QLD to sydney, the air conditioner was intermittent. This is a dual cab.

It starts out very cold and then after about 30-45 minutes it gradually stops blowing cold air. If I switched the unit off and waited a while, when I turned it back on it was cold again and the process continued

The previous owner claimed the unit was rebuilt in the last few years, it certainly starts out very cold.

There were no other overheating issues - radiator is in good condition etc.

Is this normal behaviour?

[Blknight.aus]

it is when the evaporator is icing up because the TX valve is stuck open, the compressor isnt cutting out, the temp probe for the TX valve is no longer in contact with the evaporator or any combo of the above 3.

can be a DIY fix which depending on how it was repaired last time will dictate if its an easy or a hard fix.

[dromader driver]

Mine does this when run on max chill all the time. As indicated the compressor needs to cycle which seems to melt the ice. That's in a trayback. :angel:

[Don 130]

I have a little digital thermometer with the probe into the aircon vent to the left of the steering wheel. I set the temp dial so that the minimum at that vent is 6˚C. This prevents the evaporator from freezing up and throttling the whole system, and is based on advice from an old auto electrician who got my aircon going well.
Don.

[rick130]

Most of what Dave said except for the TXV stuck open.
That would result in a higher than normal suction pressure and no icing up.

Probably just the t/stat set too low, the other things that can cause it is a partially blocked coil (dirt/dust) or very common is a blocked drain.

[Andy130]

Thanks guys thats very helpful.