weak AC

[rbiest]

2010 EX35 has weak AC. I measured performance by center vent temp [max AC, recirculate, windows closed, idle] EX35 is reading 58-60F. loaner GX37 =39F. Dealer measures by FSM/HA-32 => 50<RH<60 intake 86F, outlet 58-64F [max AC, recirculate, windows open, idle] Dealer reading is 55 on same day=95-100F. Dealer won't fix cause they say it is in spec. But it clearly has worse performance than G37 loaner and most other AC.
What could cause the performance to measure OK one way and poor the other?
are there humidity sensors in the system?
dealer adjusted "trimmer" from 0 to -6. Whats that?? how does it help?
Does TxV [themostatic expansion Valve] cycle compressor?

comparison of methods:
closed method removes RH from equation because the recirculated air is dehumidified until it has very low RH. The only variables are ambient temp and condenser airflow. As ambient temp increases, compressor will stop cycling. Once compressor stops cycling, vent temp is allowed 1deg per 1deg ambient.
windows Open method adds RH and ambient as a variables. then it sets decreasing temp drops for increasing RH.

[rbiest]

no A/C types out there??? Still sweating... i guess i will try aircondition.com

[rbiest]

weak AC fixed. It took 3 trips to dealer escalating to service manager and shop foreman to resolve it. Problem was related to ECV [electronic control valve]. the ECV throttles the compressor, reducing its capacity. Its purpose is to reduce the cycling of the compressor at low loads, thereby reducing wear on the clutch. The ECV was ok, the control signal to the ECV was OK, but the wire was loose. The compressor acted like it was too small. this made the evap temp too high because it could not get enough liquid [60F instead of 35F]. Correspondingly, the low side pressure was also high: 50psi instead of 30psi.

Now at 93F ambient, max ac, recir, windows up, I get 37-39F at center vent.... about 20F colder!!!
still shocked & appalled that 2 techs missed it even when I specifically asked them to check the ECV.

[stevewaclo]

Belated thanks for your follow up and detailed description of both the issue and solution.

Don't need to tell you how many posts just fade away with no resolution.

And congrats on your persistence at the dealership. May I presume the issue was under warranty? Dealerships will be relentless spending your money, but when they are being paid at low buck manufacturer warranty rates, not so much :-).

[AZhitman]

Actually, most posts receive an immediate response... However, this one was placed in the wrong area. I've moved it to the EX35 forum.

Welcome aboard!

[R1chard]

My weak AC issue was due to a faulty / seized compressor.
The good thing is it happened at 59.5K miles since the compressor alone was ~$1K to replace not counting labor.

Glad to hear you're running cooler now.

[XIS]

I had my compressor replaced about 3 months ago (and 3 months before wty expired)
It was still blowing nice and cold, but it would make a grumbling/gargling/ just not a smooth sound after it had been on for a few minutes. I thought my dealership would tell me 'its normal' or some other lame excuse but to my pleasant suprise, they replaced the compressor. All is good!

[rbiest]

Actually, most posts receive an immediate response... However, this one was placed in the wrong area. I've moved it to the EX35 forum.

Welcome aboard!

Thanks for the welcome, I posted in the technical area because I thought that other NI would have similar A/C control system.