C5 Aircondition problem... Help!

[DJ Clark]

I have a 1998 C5 and here is my problem...

My AC will register -39 degrees until i run my car for about 15 minutes at 50+ miles an hour. It can be 80 degrees out side and my AC will not cut on until the temp registers 32+ degrees
(It climbs from -39 to 32+ while driving).
When i cut the car off and let it sit, and then crank it again, it will fall back to -39.
Is this a sensor problem or control head? I had the control head replaced about 5 months ago and (winter) now its summer and i can see it didnt help any.
No one seems to know how to fix my problem.

Thanks DJC

 

[c4c5specialist]

Hi there,
Are you talking about the outside temperature??????
Or are you talking about the displayed requested temperature that you set?????
Allthebest, c4c5

 

[DJ Clark]

The temp that i set is ok.... see, its the outside temp. When C5s go below 32degrees the AC wont come on... why? I have no idea.
It shows the outside temp as being -39 when its 70 or 80 outside.

DJC

 

[c4c5specialist]

Hi there,
Ok, it seems to me that your outside air temp sensor is bad.
Its an inexpensive part, and mounts in the front of your radiator.
For that, it only takes about 10 mins, and pops in the radiator shroud.
Allthebest, c4c5

 

[DJ Clark]

Thanks bro!
I will check that out tomorrow. I would also think it would be a sensor is bad but to be honest i didnt know if there was an outside temp sensor.
You have been a great help.
I will check tomorrow and post the outcome.

DJC

 

[DJ Clark]

Hey c4c5specialist

I ran a diagnostic trouble codes test manually this morning and it showed the following for 99 HVAC Heater Vent-Air Conditioning

It said : B0333 H "Outside Air temp sensor open"

Does this mean the sensor is bad? This is greek to me so please look over my stupidity.

Oh, also... under BO-RFA it said: C2120 TPM System Malfunction (No Sensors Received)
What does that mean?

Thanks

DJC

 

[c4c5specialist]

HI there,
Yes, your B0333 is for your temp sensor on the outside.
As for your TPM, this is showing that you have a problem with the receiver accepting the radio signals from the tire pressure monitoring sensor.
Has the sensors been replaced, or do you have them at all?????
Allthebest, c4c5

 

[RHill]

I would also check the connections .... I have found that when temps sensors have a open circuit they read -40 and when leads are shorted together or to ground they read +300. Just a thought.