hugo2648

Yesterday, the car was at the mechanic's. And while changing the Belt Tensioner, mechanic had to remove the AC compressor as well as alternator. And of course, battery was disconnected.

Now, the AC blower does not seem to be blowing enough air even when the highest speed is selected.

What could be the problem? Is that some kind of calibration needed? How is that done?

Margate330

Hi hugo2648, have to say that is wierd as you already suspect.

Noticed in another thread you were asking about refrigerant line clamps.

Plz Tell the Story so we can understand what's going on and maybe get ideas for you.
What ALL work was done by both you and the mechanic?
Did air blow cold and strong before the system failed and needed repair?
Etc, Etc, Etc

Give as much detail as you want to make it interesting if you like.

hugo2648

Good you ask. Well, this mechanic was to change the serpentine belt tensioner (aka the $1000 tensioner). For that, the AC Compressor and alternator needed to be moved/taken out.
Well, there was no clamp for the refrigerant line (suction line I think) at the firewall. And whoosh...all the refrigerant came out.

So the tensioner was changed, alternator and compressor reinstalled. AC evacuated and recharged. Battery reconnected.
And the mechanic was saying that even at high speed, AC was not moving enough air. THat the blower was not really running at High speed even though it was set at High. This all happened yesterday. Today, my 17 yr old daughter went to work and texted me asking if somethign was done to the AC. That she feels it is not cooling enough.

Felix

I'd take it back to the shop & have them fix it as the a/c was working before.

Margate330

Thank you for extra info.

I have to look into to this to see if it's true, really a $1,000 job for that?
Even if unbolting the AC compressor and moving out of the way for clearance, I still don't see a $1,000 repair here for serpentine pulley.
Anyone else have info if this sounds right?

Is that what the tech told you?
That line has pressure in it so don't know how didn't pop apart way before all this.
Yes suction line has pressure, it sucks due to a pressure differential between the high side and low side at compressor but still runs up to 35ish psi and up to 100 PSI depending on ambient temperature when car is off due to the lines balancing themselves out.
Maybe I'm missing something but raises my eyebrows. lol


This could be a separate issue than the work you had done but it's suspicious of course.
It's extremely rare but wierd things happen.
I remember a time when someone had a transmission service and came back days later insisting we broke something because the antenna motor quit working on way home from the service. haha
In theory the work he did shouldn't have anything to do with blower speed and forced air thru vents.

He had no reason to be in there but I'd check the cabin filter for obstruction.
I'd also make sure you have it on MAX AC and measure those vent tems and let us know the best AC temps you are getting.

hugo2648

The line was holding in its place because there is another bracket closer to the compressor that clamps it down and prevents it from moving. But the end of the suction line close to the firewall (it has 2 O RIngs) was in there without any clamp.

It is called a $1000 tensioner colloquially in Youtube. Mechanic charged me $460 for tensioner change, ATF replacement (I provided ATF, Filter and gasket) and a work on the drivers side key which needed door pad removal. I got the Toyota clamp no 88718-02160 but mechanic said it did not fit.

To remove that tensioner, they say remove the radiator, the alternator, the AC Compressor - the entire shebang in the front.

spinellib

Yes, shutting off the "fresh air" vent makes a big difference.

DennisMik

All the parts from the Toyota corporation are packaged and labeled as Toyota regardless of whether is is for a Lexus or Toyota.

Not blowing enough air volume could be the the blower motor is not running at full speed. Also check that the cabin air filter is in its proper position and is not somehow plugged.

hugo2648

Is there a component or calibration that is needed to ensure blower runs at full speed?
Cabin Air filter is brand new.

Margate330

No calibration is needed but recommend you check out the AC for yourself first hand and make sure it set on max cooling and not "Auto".

Ok, this is interesting.

The AC Amplifier ECU activates the "Heater Relay" on it's path thru the circuit and throws power to the high side(+ vdc voltage) of the blower motor.
When doing this it also throws power to the high side(+ vdc voltage) of the "Blower Motor Controller" too(see red wire below).

Here is where things get interesting, it appears the low side(ground) for the blower motor is controlled by the Blower Motor Controller and by manipulating the ground it appears the Blower Motor Controller can adjust the speed of the blower motor.

Edit- flipped pages and swapped blue wires-

Ok, following the wiring and flipping pages the blue wire below marked "SI" goes back the the AC Amplifier ECU.
So, the AC Amplifier ECU tells the Blower Motor Controller how fast to run the blower fan.

Blower Motor Controller Wiring:
+B= +12V high side from heater relay
VM= ground wire from blower motor
GND= frame ground for Blower Motor Controller
SI= control wire from AC Amplifier ECU for fan speed control

hugo2648

@Margate330 - Thank you so very much.

I never seem to understand electricals. I just dont seem to "get" it. But I will again try to understand this.

Felix

You can also go thru the screen as well.....I do that sometimes when I start off w/ the a/c in ''auto'' mode, then I'd want the blower speed lower, which you'll need to go thru the screen......

spinellib

Felix, what I'd give for a simple fan switch...
I don't understand why Lexus omitted a real fan speed switch, and further complicated things with the defrost buttons.

MattRX

Just here to vent my frustrations about this too. My 2002 Highlander has such simple controls that you can adjust them without any thought. Just a simple, proven dial for fan speed, an "Auto" button for the A/C and off button for the fan speed. Works great and is super intuitive.

Margate330

So true, much simpler to diagnose fan speed without an ECU in the middle and trying to understand why the ECU is refusing to run the fan high speed and why it's not happy.

This is why I am suspicious because OP just had work done and the AC's line set came apart due to a missing union clip when lines were unclamped from the motor.
So had to get a vacuum and refill- now blower fan speed won't go on high.

So AC ECU controls the compressor AND the blower fan speed and mechanic was the last one to touch it even tho it appears they are unrelated and could be complete coincedence. lol