Thread: TD5 Airconditioner efficiency.

Originally Posted by shack

If anyone reading this thread owns a late TD5 defender with poor AC and also owns a Nanocom, I can do a bit of a Diag tune to see what the system is doing.

Just contact me if you want to have a go.

Cheers
James

Where are you based? (broadly)

Originally Posted by Captain_Rightfoot

Where are you based? (broadly)

An hour from Port Augusta..

So that's S.A. in case you haven't heard of the port.

Originally Posted by shack

An hour from Port Augusta..

So that's S.A. in case you haven't heard of the port.

Damn bit far away.

Ok update from the AC shop. They have cleaned the evaporator and it's apparently sitting at 10 degrees when idling. This sounds much better than the 15 the other day.

He also said that spraying the condenser with water made it drop to 8 or so. He said the electric fan was still working sometimes. He thought replacing the main clutch fan would help as he said "you could stop it with your hand".

So my comments about this. I have td5spy and then engine doesn't seem to really get hot. When going up a big hill or something and temps get up you can hear it start to work and the engine doesn't get hot. I thing the highest I've ever seen it circa 105 and most of the time it's high 80's or low 90's. He wants to replace the clutch fan but I'm concerned as I don't think it will help.

I would like to find out why the "ecu" doesn't turn on the electric fan or what the parameters are. It seems as though condenser cooling is the main issue.

Can anyone with a td5 AC confirm.. does the electric ac fan work when prolonged idling?

I covered this off partially before.

I need time to go through and check diagnostically what it does.

Originally Posted by shack

I covered this off partially before.

I need time to go through and check diagnostically what it does.

So I drove home from the ac place. Stop start BNE traffic. It is cool.. about 22 deg.

The whole way home the ac was oscillating between 4.5 and 6.5. So cleaning the evaporator appears to have helped as I've never seen those temps before. I need to test on a warm day though.

The engine ran high 80's and got to 91 once.. so not really enough to even get the clutch fan going.

When i stopped at home the AC electric fan was not running.

The AC guy said the fan runs sometimes.. but he didn't really know what the trigger was for it to run.

Originally Posted by Captain_Rightfoot

So I drove home from the ac place. Stop start BNE traffic. It is cool.. about 22 deg.

The whole way home the ac was oscillating between 4.5 and 6.5. So cleaning the evaporator appears to have helped as I've never seen those temps before. I need to test on a warm day though.

The engine ran high 80's and got to 91 once.. so not really enough to even get the clutch fan going.

When i stopped at home the AC electric fan was not running.

The AC guy said the fan runs sometimes.. but he didn't really know what the trigger was for it to run.

I listed the D2 HVAC settings above, other than that I can't give any more info until I have time ...

I'm guessing the ECU in the defender provides similar operation.

Just to be clear: my experience is with a P38 NOT a TD5 but most components will be roughly the same, the compressor is even fairly comparable I believe.

Having said that; The clutch fan is usually not sufficient anyway during hot days. The airflow is simply insufficient to carry all that heat from the condenser. I can not be sure how the condenser is mounted on the TD5 but in most cases with our older model vehicles there is not one of those molded fancy pieces of plastic that fits everything snugly. Often there are gaps between the different components. Point in case, on my P38 (from the engine ie the fan looking forward) first comes the radiator, then a gap and a bunch of oil coolers, another gap and then the condenser. The gaps not only exist between the cores in the horizontal plane but also on the top/bottom/sides. These gaps represent a much easier air flow and heaps of efficiency of the fan are lost by these gaps.

The engineers solved this "minor" little issue by placing an electric fan (or two in my case) directly on the condenser. Push fans are usually 10% less efficient but at least they are mounted directly atop the condenser, not losing any efficiency due to all the leaks/gaps. Also, the fact that they block airflow is compensated for by the very powerful VC fan that will force enough air through when the engine is up to speed.

Having said all that, I do not know how the TD5 ECU works without looking through the RAVE manual of your vehicle (which I do not have) but AC gas has a 1:1relation between pressure and temperature. Most AC systems use a combination of both to operate. For instance, eveporator temp is measured but not the pressure and for the condenser the reverse is usually the case. My P38 (and a lot of other systems) use 3 pressure switches that sit close to or on top of the dryer or very close to it. These have a value in which they open up and a value where they close. They control 4 different states effectively: (I know 5 steps below but step two is "do nothing")

1. < 2.4 bar the pressure is too low, do not engage the AC compressor, usually means not enough gas in system
2. > 2.4 but < 17 bar all is well, keep trucking!
3. > 17 bar, things are getting warm turn the condenser fan on (setting low)
4. > 21 bar, we are not cooling enough, kick it into high gear
5. > 30 bar we shut of the compressor since the pressure is too high.

So, like I said, not sure how the TD5 handles this without some digging around but in general high pressure should kick the fan in. You can perform a rather easy test though I think. There must be a relay that operates the condenser fan. You could take a decent piece of wire (with that I mean diameter) crimp two spade connectors on it and create a shunt wire to replace the relay and simply allow the fan to blow full speed and see what that does with your evaporator temperatures, that way you can determine if the package is performing as desired.

Cheers,
-P