Tarek9xx

2011 CTT - Unable to get the answer elsewhere

Is it possible that an intermittent blower motor causes lack of cooling (even when it actually comes on and with fully controllable fan speed)?
Thanks in advance

jpru2001

I sort of don't understand the question..how is it intermittent if it comes on and your fan speed is fully controllable?

I always used the test where you manually turn the fan up and down one notch at a time and you should be able to feel and hear a difference at each level. When I lost my blower motor, everything above the bottom 3 levels was the same, so I knew it was time to replace.

Tarek9xx

It's puzzling me as well. It started out either coming on or not at all.....then not responding to speed controls as you decribed...then I fiddled with the connector, and now it comes on every time, with full speed control, but the air is ambient (hot, because it's Florida) temperature. Makes no difference if I remove the cabin air temp sensor (which tested good anyway).

griffiths

When motor is blowing, is the ac clutch hub turning with the pulley, and is the evaporator outlet pipe back to the compressor cold?

Tarek9xx

Yes it seems that the compressor pulley is turning (but I'm not sure if that's a clutch - my understanding is that there is no clutch on these, and that a regulating valve controls refrigerant flow). As for the evaporator outlet pipe, is it possible to access it without removing the center dash? would it be on the passenger or driver side?

RAudi Driver

That doesn't make sense. Had to have a clutch or the compressor would be running when the engine is was running. That would mean there would be no difference in power or MPG whether you were running ac or not.

Have someone start car and you stand looking in to the engine and watch to see if the compressor changes in sound and pulley movement. You can see it engage and disengage. Oh, yes, the person in the driver's seat would be turning the AC on and off.

Tarek9xx

Believe me I too, thought what you're stating to be true, but have since discovered that it's a variable displacement compressor that always turns with the engine. When the valve is closed, the compressor pulley is in freewheel mode (much like in a mechanical clutch), the refrigerant does not circulate, and there is no extra load on the engine. If you have the same car with perfectly operating AC, you can confirm by seeing the hub turning even when AC is off.

Because my problem started in the middle of a heavy rainstorm (And yes I checked/cleaned all the drains), I'm inclined to believe that it's an electrical problem that is preventing the refrigerant from circulating. A faulty (usually totally broken) blower does that, because of the feedback loop to the electronics through it's speed regulator....but it's also puzzling that the blower is actually now back to working with all the speed controls and yet no cold air. Wondering if it's plausible that the circuitry within the blower regulator can still be the culprit - and hence my question in the first message. I just hate to just throw new parts on the problem without further confidence on it, based on others' experiences

CAVU

On this forum, I have read of more blower motor issues than refrigerant/compressor system issues.

My blower motor gave out at 8 years. https://rennlist.com/forums/cayenne-...acement-2.html
Near the end of the thread you will see some photos of my tear down of the bad motor. There is not just a resistor pack in there.

Check all of you HVAC related fuses.

Tarek9xx

Thanks for the response. Yes I've seen that thread, but my blower - although started out having similar symptoms to yours, it is now fully responsive to all speed commands from zero to all bars on the switch with no issues, which is puzzling. I'm hoping to find someone with same symptoms or knowledge for confirming it's an issue with the blower circuitry, (and apparently other than the resistor pack).

RAudi Driver

Another thing to check, while I go outside and check out my compressor and how it works.

The temp sensor is integrated in the dashboard and must not be covered or taped over.

Tarek9xx

Thanks for the note. My temp sensor is definitely not covered. There are other temp sensors in the ducting going from the output of the blower, such as just before entering the cabin filter, and at the side vent. They're identical and interchangeable sensors. I tested those at room temperature and in the refrigerator, with changing resistance as expected.

CAVU

here is a easy thing to try. disconnect the ground cable in the driver's footwell for about 30 minutes. That will provide a hard reboot to all of the modules/computers in the car. Every once in a while, it solves a problem.

OBTW, what part of the world is this car?

Tarek9xx

I'm glad you're mentioning this. I had read about rebooting everything elsewhere but no details on exactly how, and asked a lot about it on other threads but got no answers. So now I'm on the hunt for that ground cable you mention. My car is a USA car, left hand drive. Florida, of all places....so it's blazing hot and humid here. I haven't had to dig around the driver footwell area just yet, other than checking fuses and relays under the dash, but any tips on that ground cable would be greatly appreciated, before I take apart more things unnecessarily, and risk breaking more plastic parts. Plus I still have stitches from head surgery, and so standing on my head for working in those areas has been particularly daunting.
Thanks again

CAVU

rich022

Same happened to me- blower motor would come on intermittently. Either full air on none. Changed blower motor (1hr job). all good. As for your AC issue, i would change the blower motor first.