P38A Air Conditioning Grant

I think it should be on are you sure it’s not just for working with the nanocom for the blend motors

Air conditioning grant simply refers to whether the ECU has engaged the AC. If you have the AC off then the grant will be off, and vice versa.

Many Thanks.
It does say right hand blend motor, what would cause that ?.

According to Nanocom guides, AC Request & Grant require the engine ECU to tell the HEVAC it's ok to engage the compressor !!



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"Wow", you have done your homework, great thank you. On my nanocom it says left side blower 0 % and the right side blower is 232%. What now ?.

Try using Nanocom to change blower speeds & recirc flaps, or adjust using HEVAC speed control & see if readings change ?

I sure will ,Thank You.

Tried to adjust using Hevac speed control. but it doesn't show the readings, it says unable to communicate. The thing is it's saying there are no faults in the Hevac.

Yes Nano to HEVAC connection can be flaky. I often have to exit back to main menu, start car & then try again. Same thing happens doing things in Utility Menu, like flap calibration.

pwood999 said:

According to Nanocom guides, AC Request & Grant require the engine ECU to tell the HEVAC it's ok to engage the compressor !!

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Pins 13 & 14:
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Well, that's wrong, when the aircon button is pressed the aircon is OFF.

Agreed, but neither RAVE or Nanocom docs specify if the Active Low signal is when the AC is enabled or not !! Just the button is pressed, which could be either. Also RAVE doesn't show the wires to engine ECU either !!

I will try again tomorrow. Thanks

Radar1946 said:

"Wow", you have done your homework, great thank you. On my nanocom it says left side blower 0 % and the right side blower is 232%. What now ?.

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i would try and recalibrate the flaps using the nano function. shd not be reading 232pc...

the a/c request is active low, and grant too.

the HEVAC needs to see the request conditions fulfilled and grant low to engage the clutch (or relay to the clutch, depending on MY). i had problems with my ECM not providing the grant signal in response to the request, so i have earthed the grant line to simulate the low, and the HEVAC still cycles on/ off properly based on all its other feeds

romanrob said:

the a/c request is active low, and grant too.

the HEVAC needs to see the request conditions fulfilled and grant low to engage the clutch (or relay to the clutch, depending on MY). i had problems with my ECM not providing the grant signal in response to the request, so i have earthed the grant line to simulate the low, and the HEVAC still cycles on/ off properly based on all its other feeds

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That makes sense. The Thor and diesel are different from the GEMS. I seem to recall a guy in the States putting an LS1 engine in a GEMS and I think it was Marty that figured out the GEMS needs a signal from the engine ECU (possibly via BECM?) but the others just get an automated low signal from the BECM. It is over on RR.net somewhere from ten years or so ago. Pretty sure the solution was just to ground that wire.

romanrob said:

i would try and recalibrate the flaps using the nano function. shd not be reading 232pc...

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He said it's the blower not the flaps, but even so it should not read 232%. It's likely to be the blower motor drive transistor failed.

Datatek said:

He said it's the blower not the flaps, but even so it should not read 232%. It's likely to be the blower motor drive transistor failed.

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Good point