[VaerO]

Hey all!!

With the Christmas break coming to a close I did the long trip home from my family (Wagga) to home (Sydney). The day was pretty warm topping at 39oC in Wagga; the car was displaying a constant 33oC on the highway.

To keep the cabin cool, I set the temp to 18oC and all was fine... Until about 2-3 hours into the drive I realised I was getting quite hot! For some reason the aircon was only blowing half the amount of air as it normally does even though the the fan was set to full speed. Another 30 minutes later and there was little to no air coming out of the vents; still with the fan set to full speed.

At this point I decided to turn the climate system off completely (aircon and fan off) and put the window down. After about 30 minutes I tried turning the system back on and everything was fine, no issues. Skip forward about 1hr though and again the amount of air coming out started to dwindle to almost nothing (fan speed was still set to max).

A few notes about the issue:
1) I could hear the fan speed changing when I was playing with the dial. However, the amount of air coming out didn't change, or was very minimal.
2) The air coming out was cold, and seemed to be at the correct temperature as set by the AC.
3) The car engine temp was sitting just under half way
4) Automode was off.

What I think the issue is:
Now the fun bit. After getting frustrated and thinking about it during the drive I think the issue is the AC unit. I think because I had the temp set so low and the fan so high (combined with the highway speeds) the AC unit froze over blocking the passage of air. After coming to this conclusion, I turned the temperature up to 23oC and the issue seemed to have vanished. This would also explain why the system worked again after I turned it off to "defrost".

Has anyone experienced anything like this? Do you think my theory is plausible? Would appreciate hearing some thoughts.

Cheers

[Greyhound]

I have heard of this AC icing behaviour before and was my first thought when I started to read your post. If AC fan is spinning OK when not set max cold then I don't think you have a fault to worry about.

[CraigB]

Icing up would indicate the system needs the refrigerant levels checked.

[VaerO]

Icing up would indicate the system needs the refrigerant levels checked.

After doing some Googling it seems this is the most common problem to cause the issue. I assume the AC is a closed system, so if the levels are going down there must be a leak? Or is it normal for the levels to go down naturally as the car ages?

Sorry, I'm completely clueless when it comes to cars. I'm hoping this is something easy like adding oil to the engine, but it sounds like it's going to be an expensive fix.

[Greyhound]

It is a closed loop system but refrigerant can be lost over time and need a re-charge. That should be a simple low cost job. If you loose refrigerant again after that, it could indicate a leak. That can be traced using a dye.
I once had AC leak in a past car due to a small stone chip to the AC radiator. That radiator replacement was not a low cost job.

Always remember to run AC occassionally, even in cold winter conditions, to keep the refrigerant circulating and keep seals lubricated, which may otherwise dry out and start leaking.

How the heck do I use this system
Hi guys new the the forum.
I read today that on average the Ac system loses 55gm of gas per year.

After doing some Googling it seems this is the most common problem to cause the issue. I assume the AC is a closed system, so if the levels are going down there must be a leak? Or is it normal for the levels to go down naturally as the car ages?

Sorry, I'm completely clueless when it comes to cars. I'm hoping this is something easy like adding oil to the engine, but it sounds like it's going to be an expensive fix.

[VaerO]

Update!

Hey all,

Thought I’d post an update on the situation. I’m back in Wagga for the Easter break and have noticed a few new symptoms to add to the list. The first major new clue is that this issue doesn’t seem to be isolated to AC usage. I decided to drive home with the AC off, and if I use the fan with the AC turned off the amount of air coming from the vents still seems to dwindle (Note, the issue seems to appear more regularly when using AC but having said that I have the AC tuned on 99% of the time). Another new clue is that this issue only seems to affect the amount of air coming from the head and side front window vents (same plumbing?)  If I direct the air to my feet only the air flow appears to be normal. The last clue is that I can sometimes remedy this issue by directly the airflow though all the modes, and as long as the last mode I use is foot only, I can regain normal behaviour. However, if I go the other way it doesn’t work (so weird!).
Lastly, the temperature of the AC seems to be getting warmer. Normally I would have the AC set to 23oC and bring it down to 21oC on a hot day. Now I’m finding that I have to turn to 18oC (last option before Low (MAX)) to feel some decent cool air on a normal day!