BlackZ06,
Is there anyway that the sunbeam sensor could be affecting it?

My AC does the same thing sometimes...the light will blink on and off and the outside temp ALWAYS reads way hotter than it really is outside? I didn't realize that the computer wouldn't let the AC blow cold if it "thought" that it was below a certain temperature.

The reason I bring up the sunbeam sensor and not either of the other ones is that I've already replaced them both?

Thanks,
Donnie

 

You can only see the tip of the sensor from under the car. It is black, a little thinner than a pencil and about 1/2 inch expoused.

Good luck.

 

It reads HOTTER than it really ??? So if it is 90 degrees outside the display on the HVAC is ... say .... 110 ?????

Try this ..... turn OFF the car ....

Disconnect the sensor. When you turn the car on you should get DTC B0333 Outside Air Temp Sensor Open, and the temp display should default to 65*F (or 69 .... I forget which) . This would tell you that there are no shorts in the wiring harness/connector.

Short the sensor connector - this won't blow anything. You should get DTC B0332 Outside Air Temp Sensor Short to Ground, and the temp display should default to 65*F. This will confirm that there are no random impedances in the circuit.

I'm suspecting that there is corrosion in the connector, the second test will probably give you a temperature display different than the default and no DTC.

To ensure the sensor itself is good .... measure the impedance of the sensor itself. At 68*F, it should measure 12,493 ohms. At 86*F/8,056 ohms, 104*F/5327 ohms. That should be enough to verify it's within its expected range.

The sunload sensor doesn't affect the displaye4d Outside temperature .... the idea of the sunload sensor is to help the HVAC computer determine how much fan and cold air to deliver to mainttain cabin temperature. For example say you want the cabin temperature held at 70 degrees .... On a bright sunny day where it is ... say 85 ouside, the HVAC unit will deliver more cold air than it would if it was nighttime and 85 outside.

 

 

Excellent post ......

 

Thank you so much man!! This site is awesome!! I'll get a meter here within the next couple of days and check the resistance on that thing.

The temp range compared to what it really is, is more like if it's 100 degrees out side...my little display will say like 118!

It's not so much more than I'd like to know what the temperature is outside and the system probably works really well when it's working properly. Most of the time the AC will shut off when the car is first started up in the middle of a hot afternoon when I'm getting off work. The first couple of stop lights that I sit at if it's over 100, the AC will always kick off when I sit at idle in gear for over 10-15 seconds...I notice it because of the slight change in idle speed.

I'll unplug that sensor and spray it out with some electrical cleaner, then check the resistance....how should I short it out though? sry
Donnie

 

Straw, what you're looking at is the headlight control module. Check out the pic a few posts up.

 

To short it .... look inside the connector on the wiring of the car (not the sensor). You will see there are two connections inside the connector ..... take a piece of wire and "connect" the two. It is a 5 volt senssor curcuit, so you won't do any harm. You can't do this with many circuits because it will blow a fuse, but for this one you won't cause any harm.

Your A/C compressor is shutting off ??? Sounds like you may be low on refrigerant. Have you checked the car for DTC data ??? If the PCM (which actually controls the A/C compressor clutch .... the HVAC "requests" the compressor on .... the PCM "commands" it on....) is refusing to engage the compressor clutch, or is disengaging it when the HVAC wants it on, the PCM will set one or more DTC.

You need to display your DTC data. If you don't know how to do it go here ....

https://www.corvetteforum.com/techti...D=26&TopicID=1

When the AUTOMATIC display completes it will enter MANUAL mode. In that mode display and write down what codes you have.

A code looks like this ...... P 1234 C

The first letter will be either a P, B, C, or U ..... indicating which system the code is for.

The following 4 numbers are the code

The last letter will be a C or an H (sometimes both).

Post the ENTIRE code (as in the example ..... P1234C), and list ALL the codes found.

 

Have you cleaned the condensor? They can hold alot of trash between the radiator and condensor, where you can't see from underneath. A dirty condensor could be causing your high pressure to climb to a point where the high pressure safety kicks the compressor off. That should set a code.
As far as the ext temp reading goes, is it more accurate when you are moving, and away from hot concrete streets? Mine always read high in stop-n-go city traffic, but when I get on the highway at speed, it comes back down. The street surface may be in the 120*-140* range, which can affect your readout at a stop.
Like BlackZ06 said, you need to check codes. Also you need to check and properly charge your system.

 

Guys,
I went out and checked my codes again today and there were none in the HVAC part but here the are the other ones...

U1255 H
U1016 H
U1160 H
U1088 H
U1064 H
U1096 H
U1040 H

B2583 H
B1001 HC
B0521 H
B2172 H
B2177 HC
B2197 HC
B2187 H

C1222 H
C1226 HC
C1233 H

I know that the "U" codes are loss of communication to everything codes lol...but I haven't cleared them in a long time until today.

The "C" codes are due to me either needing to replace my actual wheel hubs or I'm gonna try and replace the connectors on the back here eventually and see if that fixes the codes first...they're both due to excessive wheel speed variation on RF and LF with the RF one also saying that the circuit is open or shorted...

Now I'm pretty sure that the B1001 and B2583 codes are due to the fact that I still don't have my original PCM in the car and have to do with the SRS system correct?

The other "B" codes have to do with the issues that I've been having with my driver's side seat and that along with this AC ISSUE and the P0327 code (front knock sensor circuit) are the on-going problems that I still don't know how to figure out...?

Thanks for any suggestions,
Donnie

I still haven't gotten enough time to let the car sit while I'm not at work long enough to blow out the condenser and radiator...there does seem to me quite a bit of hair and very fine debris stuck in the fins of the condenser and radiator but I had been more checking for big stuff such as a plastic grocery bag or something to be blocking air flow....?

I might try disconnecting the battery and pulling the PCM fuse again and see if it makes any difference on the codes?

I just had the AC refrigerant level checked and topped off like 6 months ago but I'll go in and have em' check it again just to be sure.

 

None of those codes seem relevent to the A/C problem. I'm still leaning towards the condensor being dirty, if your 134a charge is good. You really need to get a set of gauges on it and see where the pressures are when the compressor kicks off.

 

I went out and unplugged the sensor and the code popped on. B0333 I think? I still haven't been out to my Mom's house, where the meter is...I'll head out there tomorrow afternoon hopefully and then I'll short the connector, clean out the condenser and radiator, check the resistance and report back.
Thanks again!
DZ

 

Oh and it DID default to 69 degrees...
DZ

 

Also BlackZ06, should I measure for the 5 volts coming out of the connector? Or how do I measure the impedance of the circuit?

Sorry,
Donnie

 

Basically you don't need to check for the 5 volts ... when you "short" the two wires together the HVAC will throw a code if it sees 5 volts, as it expects to always see something less as the sensor always provides some resistance on the circuit.

If you have a DMM (digital multi-meter) set the **** to the lowest ohm setting (look for the "Omega" symbol ... look like a circle open at the bottom with a little "base" at the ends of the break in the circle) ....
and measure the sensor, just hook the two cables (probes) into the sensor connector .... then read the ohms and compare them ....

At 68*F, it should measure 12,493 ohms. At 86*F/8,056 ohms, 104*F/5327 ohms ......

try both your old and new sensors ... they should theoretically read the same impedance at a given temperature ....

 

Thanks so much man!
DZ