| ID | Status | Date | Year | Make | Model | Transmission Type | A/C Controls | Public/Private |
|---|---|---|---|---|---|---|---|---|
| #13708 | Closed | 2009 | Chevy | Tahoe | public |
 |
My 2009 Tahoe A/C was very cold and after Ecu and pcm software update throw Acdelco SPS |
 |
Looking at the data it looks like you have auto a/c controls. If so there may be more than one ambient temperature sensor. Be sure to check both locations. The following link is for an older Tahoe but the general locations should be the same. Consider monitoring the temperature data while the sensor is disconnected and while jumpering the two terminals together. A drop in temperature will show fairly quickly in the data but a rise in temperature will require using the scan tool special functions to update the OAT or by depressing the Mode, Front Defrost and Rear Defrost buttons on the control panel simultaneously. I was also concerned about the * showing in the data for the low pressure switch. Now with all of that information aside you stated that the compressor is coming on. Is the system correctly charged? Have you looked at the door positions to make sure actual and commanded values are the same or at least withing a few counts of each other? Are there any codes stored?
|
|
|
I have manual control CJ3 so only 1 ambient temp sensor in the front grill and i have changed it to new one. |
|
|
At the ambient temperature sensor there should be two wires. Dark green and light green with a black stripe. The dark green wire is the low reference signal and should effectively have a circuit to ground. The light green/black wire should have five volts on it with the ignition on, the HVAC system on and the sensor disconnected. The low pressure switch should have two wires going to it. A dark blue wire and a black wire with a white strip. The dark blue wire should have voltage on it with the ignition on, the a/c turned on and the switch disconnected. I could not find the voltage specification but I think it should be battery voltage. The black/white wire should have a constant ground. The outside air temp raw reading reflects more real time data and the outside air temp filtered is an average of the raw data over a minute or two of time depending on vehicle speed or if the outside temp data is manually reset. The actuator counts normally do not go to the full extremes of o or 255. Instead they have a buffer of at least 5 to 20 counts. Other than the data what is the symptom or complaint from the driver? What is all of the data you have accumulated specific to the complaint? |
|
|
The thing is when AC on the compressor is work and after minutes i hear it turn off for secondes and come back again. |
|
|
Okay, it would seem what you have going on is a short cycling issue and that means going back to basics and checking refrigerant pressures. I will need to know both the high and low side pressures from a set of a/c gauges during at least four different events. System first turns on, while vent temperatures seem good, just before the compressor cycles off and when the compressor cycles back on. I also need to know the a/c high pressure sensor readings from the scan tool during these same times. Be sure to record and document the real ambient conditions while testing. Outside temperature and humidity. Also document vent temperatures. Prefer the vent temps with the fresh air door closed, windows up, doors closed, engine rpm’s above 2000 and blower on high. If you are working by yourself you may need to do the testing several times in order to record all of the needed data. |