AirCon crap at idle but ok above 1500 rpm

[Sheik Jabooti]

Well not exactly a 2.5T issue but I do have a 2.5T so couldn't figure out where to post.

Anyway, problem is the aircon is basically useless when sitting at idle. Hardly any noticeable cooling capacity. When driving or if I rev the stationary car to 1500 rpm or above aircon works fine.

A mate suggested the compressor was stuffed as it wasn't engaging at low rpms. The cars only a few years old (MY07) so I thought that shouldn't be the case.

So anyone got any ideas or had this issue?

Cheers,

David

[smythie]

Could it be low gas/refrigerant?

[tangcla]

Sounds like low gas to me...

[champ]

I noticed the exact same issues you mentioned 2 days ago when it was 37degC outside. Put it down to low gas. How sure is your mate about a stuffed compressor?

Edit: Forgot to mention that the aircon was working fine yesterday when it wasn't as hot.

[Sheik Jabooti]

Mate (mechanic) reckons that if the aircon works while driving, then the gas levels are ok.

So has anyone had this problem and then fixed it by re-gasing?

[Std08GTB]

Is this your first summer / hot weather in this car?

Mine was crap unless it was on re-cycle.

[Sheik Jabooti]

Yep it is my first full summer with the car. But I had a similar MY07 GT last summer but it was a manual not auto.

Generally speaking I always run the aircon on recycle so it's not that.

So does yours work ok at idle?

[champ]

Is this your first summer / hot weather in this car?

Mine was crap unless it was on re-cycle.

Funny you should say that. It is my first hot weather with this car. Aircon was on recycle.

Unlike the Sheik, mine's a manual.

Waiting for the next hot day to test it again.

[champ]

Sorry about the double post, but thought this is somewhat useful.

A few causes of low cooling efficiency or no cooling at all at idle (stationary/low speed) are:

• Lack of air flow across the condenser. We ensure the electric cooling fan motor near the condenser is coming on, or in models that are equipped with a fan blade we make sure this fan is turning and is turning very fast.

• Low Freon levels. Freon level and pressure are checked - by law, this must be carried out by a qualified air conditioning mechanic, like ours . This is one of the most common reasons why your aircon isn’t working. The system needs re-gassing every one or two years.

• Overheating. If the engine is running hot or overheating, it can have a noticeable negative affect on the aircon system. Some cars have two electric cooling fans, one for the aircon condenser and the other for the radiator. Usually at idle on a hot day with the aircon on both fans will be on. We check to ensure they are both working properly.

When your car is travelling at higher motorway speeds, the compressor is pumping the Freon throughout the system much faster and harder than at idle. There is therefore a dramatic increase in air flow across the condenser due to higher mph winds, and the engine is usually operating at a cooler, more efficient temperature as well, thus allowing the air conditioning system to operate efficiently.

So an air conditioning system that is somewhat low on Freon can still feel comfortable at motorway speeds due to the added air flow across the condenser which can overcome the ill effects of slightly low Freon.

[overl0ad]

the liberties come with a compressor cut out switch.

if you floor your car, you'll notice that the fan is blowing, but the AC isn't cold. might need to be driving it like a loony to really get what i mean.

so, under 1500, the compressor don't run flat out. so it feels like it's not cold.

i've had the 2.5i and now own a GTB. same same for the AC.

on the good side... you can kinda leave the AC running when on track without too much loss.

i'm gonna try it on the dyno with and without the AC. would be interesting to find out.

[Std08GTB]

A few things I found affect it significantly.

If the car has been sitting in the sun on a 35+ degree day it takes a full 20-25 minutes of driving to have the aircon work properly, regardless of fresh or recycle.

That was in white, but Black cars like my 07 was sometimes never work properly it would seem.

Recycle does work better particularly on the really stinking hot days.

The reality is that the Liberty aircon is not really all that good. Even a basic Commodore or Falcon aircon will work much better.

If you have the option to park in the shade it will work far better from the start.

[Sheik Jabooti]

Great feedback guys. Thanks, at least I know now that it's not just me

I think half my problem is that most of my trips are for 10-15 minutes so the aircon never really gets a chance to cool all the components down. Sitting at idle, possibly with aircon gas a little low then struggles to cool the engine components before it makes it into the cabin.

Next hot period I might book in for a regas and see if it helps.

I think ultimately the problem is that the Japanese don't know what real hot weather is. In saying that, the car heater is awesome

[Sheik Jabooti]

So two years later I decide to get the regas and guess what...Icy cold aircon. It takes about 1 minute to get cool and works fine on idle.

Can't believe I put up with a hotbox for the last two summers for the sake of $132 and 2 hours in the shop.

Ah well, all in all it was a happy ending to the story. Now I can drive around with aircon on auto and it actually cools down to the temperature I set.