One time I get 62F, the next time, later in the day i get 20F - It's 80+F outside
So that makes perfect sense - 20F outside equals no demand for A/C!!
Also I noted that colder air on one side compared to the other side - So I guess the sensors in the air ducts?
My other issue is a noisy compressor which is due to low refrigerant or compressor on the way out?
Thanks for all your help guys!
Joined: May 15, 2009 Posts: 190 Posts per day: 0.06 Location: CT
Posted: Wed Jul 14, 2010 11:14 am Post subject:
Last year, my 00 LS had the a/c compressor running full time when the switch was on. Normally, the compressor cycles on and off, but mine just stayed on. I had more cold air than I could take, on a 95 degree day with 85% humidity I had the fan on low and was frozen after just 10 miles. It turned out to be 1/2 lb low. They told me that 00 was an odd year in that normally the a/c gets less efficient as the refridg level drops, but the 00's compressor will run all the time. Just started doing the same thing again last week, along with a noisy compressor so I'll know later today what the result is.
The OP might want to listen and see if the compressor is cycling, if not, you're likely low on freon.
The ambient temp sensor behind the grill has no bearing on the A/C...
In fact, if you don't have the DIC, there is no ambient temp sensor there at all..
Just for giggles I sprayed caned air (inverted) on the sensor. Went to –23F, compressor clutch would not engage, the light on the control blinked when pushed. As the temp came up past +40F the clutch engaged. That sensor dose control the a/c. Before you call bull$hit, try it.
I also have a ’97 GP with the pigtail but no sensor so I know what you are saying. Darn if I know how that one works.
Kinda difficult to try it when I don't have an Impala...
And since the ambient sensor is wired directly to the DIC, I don't see how the HVAC could use it... much less rely on it when it's an option and the vast majority of Impalas don't have it
EDIT: And here is how it is done... by physics. When ambient temperature is low (below 40deg or so), the low side pressure sensor will prevent the compressor from turning on because the ambient temp causes the freon pressure to drop below the pressure turn on threshold...
The PCM will enable the A/C compressor clutch whenever the engine is running and the A/C has been requested unless one or more of the following conditions are present:
* Throttle angle is more than 96 percent.
* A/C head pressure is more than 440 psi (4.6 volts) or less than 32 psi (0.3 volt) as determined by the A/C refrigerant pressure sensor.
* Ignition voltage is less than 10 volt
* Engine speed is more than 4400 RPM for any amount of time.
* ECT is more than 124°C (255°F).
* IAT is less than 5°C (41°F).
It uses the iAT to determine the exterior temperature...
I guess it's possible that it may factor in the Ambient Temp from the DIC if equipped, but i would be extremely surprised
On a semi-related note, if there a complete A/C troubleshooting article somewhere on the forum? I haven't come across anything in my travels, but my A/C stopped working more than 2 years ago, and this summer is HOT.
You cannot post new topics in this forum You cannot reply to topics in this forum You cannot edit your posts in this forum You cannot delete your posts in this forum You cannot vote in polls in this forum