HVAC-problem on -97

[maxm]

I have a HVAC-problem. Wen i take the car out of my heated garage (18 deg. C inside and 5 deg. C outside ) and i have the HVAC in AUTO everything seems to work. After 10 min driving, wen the engine woms upp the EXT temp is rising somewere betwen 15 and 20 deg. C and the AC-kompressor stopps. It is still coming warm air into the car but the EXT temp schows
20 deg C wen its only 5 deg outside. If i then turn off the engine and make a schort stopp everything works normaly for a few minutes and then the EXT temp is rising again.
There are no codes. Any ideas ? Have only been driving the car for a few houers.
Max M

 

[c4c5specialist]

Hi there,
I would recommend that if you did not retreive codes from the HVAC computer, that your inside air temperature sensor may be amiss.
I would have your Corvette specialist check out the actual temp, vs read temp by the sensor, and let us know what you have.
This will give us some insight as to what may be causing your concern.
Allthebest, c4c5

 

[maxm]

c4c5 spec. Thanx for your help. The matter is a litle difficult to explain.
If i set the inside temp on the HVAC on 20 deg C it delivers the asked temp. If i then want to increase the temp. in the car to 25 deg. C thath seemes to work to. It is the outside temp shown on the HVAC display that goes wrong. i don´t understand the conection between outside tempsensor and AC-kompressor.
Max M

 

[c4c5specialist]

Hi there,
I would suggest that you check to see if your external sensor is mounted correctly.
Please reference the attached diagram of the front radiator shroud, and surrounding parts.
Let us know if it is attached at the lower part of the shroud, on the passenger side.
Allthebest, c4c5

 

[maxm]

Hi....This is wath i did. Turned on the ignition, the EXT sensor schowd garagetemp. Found the sensor, loked over the conection. Everything OK. Blew hot air on the sensor with a hairdryer. EXT temp rised.
Started the engine, HVAC in AUTO and took the car out. EXT went down to 5 deg.C after a minute or so(that was outside temp.). Started to drive. After 5 minutes the AC-kompressor stoped(engine now hot)
and a few sekonds later the EXT tempreading on the HVAC slowly went upp to 15 - 20 deg C. At home i stopped the engine, opend garagedor, started engine, AC-kompr. went on, ETX temp schowd 10 deg. C. After 30 sek. at idle AC turned off.
Can you get eny sense off this ?
Max

 

[c4c5specialist]

Hi there,
Does the LED on the climate control head for the AC button turn off, or blink??????
c4c5

 

[maxm]

Hi...the button does turn off. Sometime i have seen to blinks before the light goes off.
Max

 

[c4c5specialist]

HI there,
Ok, now we are getting somewhere.
I would suggest that you have the system checked for correct refrigerant capacity, and charge.
It is possible that you have a pressure problem, that is unrelated to the control head.
This should be your next course of action.
Allthebest, c4c5

 

[maxm]

OK...i will do that. I think i heard a " hissssing " sound from the passenger sid of the engine room yesterday wen i parked the car in the garage. I will come back to you in the matter wen i looked at the pressure.
Thanx // Max

 

[c4c5specialist]

Hi there,
The hissing that you hear is normal, and not a problem.
There was a revision in the lines, later on in c5 production that address the hissing noise.
Allthebest, c4c5

 

[maxm]

Hi again.
Had the system checked and refilld today. There was 20% missing. This is wat happend on the testdrive. Weather: Sunny. 10 deg.C. Car standing in the sun for 1 houer.
The AC was on for 30 min. EXT schowd 16 deg. AC went off for 5 min. Then on for 10 min. And off again. Reading the manual i think the AC is OK. It schould come on and off wen needed. Every other funktion seems OK in the HVAC.
Wat do you think ??
EXT temp is to high and changing betwen 15 -- 22 deg. If the car has been standing for a few minutes the EXT temp is OK for 1 min and then rises again. Is it the outside sensor after all ?? Is there some conection betwen the EXT temp and the HVAC or is it djust nice to have the outside temp??
Max M

 

[c4c5specialist]

HI there,
I am sorry, but your next course of action is to retreive a data stream from the control head, as I am thinking that something is wrong.
You will need to check the PCM, and the HVAC for data.
Are they absolutely certain that there were no codes in the PCM??????
Allthebest, c4c5

 

[maxm]

Hi again. I think refilling the system was OK. There was some gas missing. Abaut the codes...i did check them myself. I have 250 km to the nearest GM-dealer. I hold the OPTION button and press the FUEL-button 4 times and get the codes, or are there other ways to do it ??
You think i schould take the car to a specialist. Is that right ? Is there eny sense to change the outside temp sensor ??
Max M

 

[maxm]

I discovered another thing today. Wen the HVAC is in the OFF position the EXT temp is rising. Does that help ?
Max

 

[maxm]

Hi...I put in a new outside temp. sensor today. Made a schort testdrive and the HVAC seems OK.
Thanx c4c5 for your help.
Max