Sorry if my thread has been confusing, but the issue is that the Aircon performance is intermittent. It seemed to relate to outside temperature but this is not confirmed as it doesn't seem to be consistent with that either.

So with this last effort to determine what may be going on, I had the technician perform the general checks I mentioned... of course the Aircon was performing flawlessly while the car was under his care. Frustrating....

I had a recent heart attack ( not a good thing at 54 with Cholesterol at 180!) so I have been working from home and not driving the car.

I'll update any progress when I am back driving my commute routine and trying to get a consistent fail mode. Very frustrating.

bad expansion valve as for the Cholesterol remember a balanced diet does not include a drive up window and to be battered is for women not food

Well, because I have been working from home and the car is garaged, the Aircon has been working flawlessly. If the expansion valve were bad, wouldn't I get intermittent performance regardless of the ambient temperature state of the car?

In other words the only times I have experienced the Aircon issue is after the car was parked out in the full day hot Arizona sun. My employer can't fund the covered parking. This is a new issue, so don't make the statement.. What do you expect with a hot car. It used to always cool down no problem.

So I am suspecting something that would be related to or more sensitive to ambient temperatures. So does this still make sense for an expansion valve?

So now I have confirmed the following.

1) When I parked the car in the HOT arizona sun all day, then on the drive home the AIRCON operated intermittently then after a few miles blew hot air for the majority of the ride home.

2) today I found a parking spot on the back side of the Building that provides shade for the car in the afternoon. The AIRCON blew nice cold air all the way home. It was great !

So what sensor could be going bad to cause this sensitivity to sitting out in the direct sun? This problem didn't occur previously. The ambient temp today was about 109 F

Thanks for any insight

Now that I have been back commuting I believe I have isolated the root cause as the A/C ECU. If the A/C ECU is subjected to high temperatures as a result of Direct Arizona Desert Sunlight for multiple hours, the A/C operates marginally then starts blowing warm air. If I provide Shade for the dash using a Windshield shade, the A/C operates normally. So this indicates to me that when the A/C ECU is simply too hot one of the many control lines becomes dysfunctional. All functions on the display have never shown problems despite this A/C issue, so I didn't think the unit had a problem.

Well, I found I used AC/ECU and replaced the unit. Same symptoms were exhibited as previously described. On Some days when the outside temperature was Hot the Air conditioning would blow nice and cool then start blowing hot after 10-15 minutes of the commute.

So then only thing I could imagine doing was to take the car to yet another expert.

They diagnosed that the coolant amount was half of factory specification. He stated that the refrigerant capacity should be 23 oz and it was about half that. So that when it was hotter outside , the system could not keep up.

We'll I am looking forward to this being the solution! :)

Now, the first tech I had look at my system only stated that he looked at pressures (Hi/Lo) and they were in specification. Sounds like I got caught with a Tech that didn't look at the volume of refrigerant versus just looking at operating pressures ?

Is that possible?

Thanks

Well..... the problem is not fixed. 15 minutes into the drive home and warm air starts coming out of the vents :mad: :mad: :mad:

I turn the A/C off and wait for 10 minutes and the air is blowing cold again.

I have yet another appointment on Thursday with the shop to see whats up....

Looks like MXMIKIE nailed it !! The shop did manage to replicate the issue and found that the expansion valve must be the problem.

The Expansion Valve is sold separately and the total bill was $462.04. The Expansion valve was priced at $53.00.

$75 for troubleshoot
$297. Labor
$53 Expansion valve
$29.76 shop supplies(?)
$7.28 tax

So I felt good at $462 out the door. Now I hope this was it !!

Thanks for the inputs.

Ac Repair technicians can check the ac system, quickly diagnose the problem and provide cost-effective repair solutions. They offer repair, service, replacement, recharge, compressor and more for entire automotive HVAC systems heating, cooling, and air exhaust filters.