Playing around with the 2.7 software (ECU and TCU)

[iSullivan]

Stage: just starting ,done.
Windows 10 and mpps 13 worked first time. Downloaded my tune, just glancing at it it has been modified. Added the cooling mod and drivers wish 0 column to sheepishly test writing back and it worked. Where do you share the files ? Can't wait to hear your opinion on mine.

[JeanLuke]

I have recently been playing with the aircon, gassing it with a hydrocarbon refrigerant. Long story short... I have proved that the hydraulic radiator fan responds to the air-conditioning system pressure sensor. This is mentioned in the service manual, but I have not been able to prove it until now.

I cannot find a map between A/C pressure & fan speed in the ECU. Has anybody else found it?

EDIT:
I thought I should unpack this a little, albeit off topic. The HC refrigerant does its phase change at lower pressures than the standard HFC, lower by about 20%. The factory manual gives temperature-pressure tables for the high-side pressure, based on HFC. The manual also gives a description of the hydraulic cooling fan being controlled by a combination of coolant temperature and AC pressure. Switching to HC refrigerant, the hydraulic fan was not responding to the AC pressure, because it was below the point that would trigger a ramp up.

I deliberately overcharged the system a little with HC refrigerant, to bring the high side pressures up to be inline with the manual's tables. The cooling fan started to work as expected, ramping up to around 20% speed when the AC pressure hit around 20 bar. This has improved the AC performance. The downside is the gas-liquid phase change is now happening in the first half of the first pass of the condenser with an ambient temperature in the mid 20's. (You can feel the end of the phase change. The condenser temperature starts to drop once the phase change is completed. The latent heat has been exhausted and it is now cooling liquid.) Overcharging carries almost no risk of feeding liquid into the compressor on the low side because the TX valve regulates against this based on HFC. With HC having a lower dew point compared to HFC, there is "headroom" here. Note also the lower dew point of the HC means lower temperature at the evaporator. This is good!

My concern is that on a cold day it may move the phase change back to inside the compressor, which will end badly. I'd like to be able to re-map the cooling fan to the lower HC pressures and take some of the extra gas out of the system to mitigate this.

[Adrian D]

There are 3 maps for the cooling, although all of them have the same axis values...

[JeanLuke]

Yeah, I have found them (edit: I mean those three maps). They all relate to coolant temperature and are all the same. None of them relate to AC pressure.

[5oclock]

The propane/butane mix has lots of advantages for us bush mechanics and its the best from the enviro point of view. Not really any boxes unticked.
I was just using straight propane( BBQ gas), but have been using M30 (propane/butane) for a year or two now. It doesnt leak through the hoses like the HFC stuff does either.
Can you remember your hi and lo side pressures and the ambient temp when you charged it--just curious, got to replace my TX valve before the weather heats up( LOL, just heading for winter in Gippsland and worrying about the AC performance).

[JeanLuke]

Let's not derail this thread with air-conditioning. If you want to start another thread we can discuss it there.

[Adrian D]

Originally Posted by JeanLuke

Yeah, I have found them (edit: I mean those three maps). They all relate to coolant temperature and are all the same. None of them relate to AC pressure.

That's why I mentioned that they might not be correct for A/C. Nothing can be 100% sure, like I had trouble with the EGS52 torque limits. It took a bit of real life testing to figure those out...