Due to weekend no word yet. Faintly remember tech saying checked the refrigerant. Should know tomorrow.

What can get worse by taking temp sensor? Something really bad?

 

Maybe that was a bad choice of words. Just seen weird issues when that temp sensor goes out. You should be fine.

 

Yup no difference. After removing ambient temp sensor and using AC in manual mode only it still went out. So installed it back.
Well have to wait till I get detail info on what was already done by tech.

 

here is reply form AM dealer tech, sound like he did pretty good work up
what do you guys suggest?

When I first got in the vehicle I brought my temp probe with me and sat
outside with the car running while monitoring the vent temperature. The a/c
was blowing cold and then the fan just cut out completely. This tells me
there's an issue with the fan control system. The fan is inoperative even in
manual mode so it's not a sensor issue. Your ambient temp sensor was
displaying the correct temperature.

The a/c system has several temp sensors and pressure switches. It uses the
ambient sensor, interior temp sensor, evaporator temp, and sun load sensor
to regulate the fan speed and/or outlet air temp to maintain the desired
cabin temp when it is set on "auto" mode. There is also a high/low pressure
switch on the a/c refrigerant system to protect the system from excessive
pressure/low charge state. If the a/c system high/low switch is tripped the
a/c compressor will turn off, however, the interior blower fan can still be
operated. Let's put it this way, you can remove all the refrigerant and
unplug the temp sensors and the fan should still be able to operate, with
limited function.

Using a volt meter I verified the output voltage from the blower resistor
was gone when the fan cut off, and verified proper grounds were still
present. I swapped the blower resistor with a know good unit but the issue
was still present. I could see the reference voltages from the a/c control
module to the blower resistor drop out when the blower quit. The service
manual doesn't state what the supply voltages should be under different fan
speeds, although when the fan operates I can see the reference voltage
change in steps when the fan speed is changed. What's interesting is there
is a fan blower relay that is operated by the a/c control module, even when
the blower stopped working the relay was still activated, this led me to
believe there was an issue with the a/c module. As you already know I
swapped the a/c module with another vehicle and that didn't fix it either.

We ran out of time Friday but the next thing I wanted to do was test the
supply voltage and ground at the a/c control module and also swap the center
console module. The center console module actually tells the a/c module the
requested switch/temp functions from the driver controlled switches via a
c.a.n type network so it's certainly a possibility. Like I said before this
is the first time I've seen this issue so I won't rule out that I've missed
something, but based on this I feel I'm on the right track.

It's a good observation you made about it acting up differently under
different ambient conditions and I will certainly look into it, but it was
still acting up regularly in our cool 74 degree shop. Maybe it even has
something to do with the rain, I suppose anything is possible at this point.

Hope this information helps, let me know if there's anything you would like
me to clarify.

 

Nice, I would just let the tech be..he is on to something with the CCM, I'd let him play it out

I've never tried a empty system in manual mode to see if it would keep the fans running, in auto mode it will cut off the fans..

I'm curious, keep us posted

 

Under bonnet fuse box been checked? Lots of heat and water gets to it.

 

I am going to dealer tomorrow, keeping finger crossed.
Something has happened previously AC was on and off almost 50-50%, now is mostly off and occasionally on so hopefully tech will be able to pin point the problem and fix it.

 

Ok car is back from dealer.
They replaced HVAC module
Part # 8D33-18C612-AB price $ 895
Cost $ 165 for diagnosis, $165 for installation
360 miles of diving plus tolls
plus tax.

I was able to find same part priced at HWM aston Martin for 310 British pounds plus shipping and import duty which will be probably around $ 510-530. So there is quite a bit mark up by dealers.

But atleast car is back in my arms (I missed her) and Ac seems to be working.
Next time I will always order parts my self. I mention the price difference to service rep. , no adjustment offered.

Thanks for the help.

 

Good show...but thats not the HVAC module, it's the CCM (Center Control Module)..controls everything on that ski slope and among other thing..

A north american dealer will not be able to compete with UK pricing, the list price in the UK is lower than the dealers cost price in north america for 8D33-18C612-AB ..I'm sure they could of given 10% off but not much more than that..nonetheless, glad it all worked out

 

Yes it is CCM. thanks for correction.

May be we should make it public/sticky that if one wants to save money, ALWAYS buy parts form UK, rather than local dealer in US?