external temperature sensor does not reflect correct temp
Thread Starter
4th Gear
Joined: Jul 2006
Posts: 4
Likes: 1
external temperature sensor does not reflect correct temp
I recently purchased a '98 vette. About a week after I purchased it, I noticed that the external temperature sensor doesn't accurately display the external temperature. For example, it might be 75 degrees in the garage, but the external temp displays 32 degrees. At first, after the car was out for a while (5-10 minutes), the external temperature would gradually climb to the correct temp. Lately, however, the external temp isn't changing. I live in New Mexico and it hasn't been 32 degrees in many months; however, that's what the external temp is reading. The problem is that because the temp reads 32 (or 39, or 46 degrees --it varies), the car desparately wants to turn on the heater. With it being 96 degrees here, the heater is the last thing I want.
I've taken the car in once, but they couldn't diagnose the problem. Any ideas? Anyone else have this problem?
Thanks!
I've taken the car in once, but they couldn't diagnose the problem. Any ideas? Anyone else have this problem?
Thanks!
Race Director
Joined: May 2000
Posts: 14,542
Likes: 5
The external temperature sensor has nothing to do with turning on the heater. You do that by setting the inside temperature desired.
It could be the sensor, it could be the HVAC system.
Easier to replace the sensor first.
It could be the sensor, it could be the HVAC system.
Easier to replace the sensor first.
Drifting
Joined: May 2000
Posts: 1,917
Likes: 3
From: Southern NH
A lot of misinformation here.
The external temp sensor affects the operation of the HVAC system. For example, if the temp reading is less than ~38*F, the AC will not be allowed to turn on. In fact, even if you set the HVAC to the coolest setting of 60*F, the system will not blow cold air (only fresh outside air) since the AC is disabled. Your sensor is likely bad or the connector has corroded affecting the impedance of the circuit.
To temporarily fix your problem, unplug the sensor and the temp will default to ~ 58*F, which will allow your AC to operate. The sensor is located under the nose of the car on the passenger side of the radiator cavity just above the air dam. You can reach it by raising the hood and reaching down between the frame rail and the rad cavity - just unplug the connector.
The sensor itself is only about $12. You may need to also check the connector for corrosion to may sure it's not part of the problem. You HVAC is probably fine.
The external temp sensor affects the operation of the HVAC system. For example, if the temp reading is less than ~38*F, the AC will not be allowed to turn on. In fact, even if you set the HVAC to the coolest setting of 60*F, the system will not blow cold air (only fresh outside air) since the AC is disabled. Your sensor is likely bad or the connector has corroded affecting the impedance of the circuit.
To temporarily fix your problem, unplug the sensor and the temp will default to ~ 58*F, which will allow your AC to operate. The sensor is located under the nose of the car on the passenger side of the radiator cavity just above the air dam. You can reach it by raising the hood and reaching down between the frame rail and the rad cavity - just unplug the connector.
The sensor itself is only about $12. You may need to also check the connector for corrosion to may sure it's not part of the problem. You HVAC is probably fine.
Thread Starter
4th Gear
Joined: Jul 2006
Posts: 4
Likes: 1
John, you seem to have understood the problem perfectly. I'll replace the sensor and take a look at the connectors.
Thanks so much--I really appreciate your help and advice!
Thanks everyone else for your input
Thanks so much--I really appreciate your help and advice!
Thanks everyone else for your input
Race Director
Joined: May 2000
Posts: 14,542
Likes: 5
Originally Posted by JC in XTC5
A lot of misinformation here.
The external temp sensor affects the operation of the HVAC system. For example, if the temp reading is less than ~38*F, the AC will not be allowed to turn on....
The external temp sensor affects the operation of the HVAC system. For example, if the temp reading is less than ~38*F, the AC will not be allowed to turn on....
Betty posted: "The problem is that because the temp reads 32 (or 39, or 46 degrees --it varies), the car desparately wants to turn on the heater. With it being 96 degrees here, the heater is the last thing I want."
Like I said in my post, "The external temperature sensor has nothing to do with turning on the heater."
That's correct, right, John? Where's the "misinformation"?
Heater is not the same as A/C, yes?
Just checking.
Last edited by EHS; Jul 26, 2006 at 06:47 PM.
Burning Brakes
Joined: Nov 2004
Posts: 1,028
Likes: 0
From: Fort Worth Texas
Originally Posted by EHS
John -- Like Betty said, you know your stuff.
Betty posted: "The problem is that because the temp reads 32 (or 39, or 46 degrees --it varies), the car desparately wants to turn on the heater. With it being 96 degrees here, the heater is the last thing I want."
Like I said in my post, "The external temperature sensor has nothing to do with turning on the heater."
That's correct, right, John? Where's the "misinformation"?
Heater is not the same as A/C, yes?
Just checking.
Betty posted: "The problem is that because the temp reads 32 (or 39, or 46 degrees --it varies), the car desparately wants to turn on the heater. With it being 96 degrees here, the heater is the last thing I want."
Like I said in my post, "The external temperature sensor has nothing to do with turning on the heater."
That's correct, right, John? Where's the "misinformation"?
Heater is not the same as A/C, yes?
Just checking.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Grand Sport & Grand Sport X Launch Alongside All-New 535hp LS6 V8!
Michael S. Palmer
5 Reasons Bad Drivers Crash & 5 Ways to Avoid a Costly Mistake!
Joe Kucinski
7 Bolt-On Upgrades From Extreme Online Store to Level Up Your C6 Corvette
Pouria Savadkouei
How Likely Are These Five 2027 Corvette Rumors to Be True?
Brett Foote
9 Best Corvettes You Can Buy for Half Price (& 1 You Should NEVER Buy!)
Joe Kucinski
8 Very Best Corvettes of Amelia Island 2026
Joe Kucinski
Top 10 WORST Corvette Engineering Failures of All Time!
Joe Kucinski
10 Records the C8 Corvette Generation Has SMASHED (& 1 Glaring Failure)
Joe Kucinski
7 Wildest Corvette Concepts Ever Made
Brett Foote
Drifting
Joined: May 2000
Posts: 1,917
Likes: 3
From: Southern NH
My comment was geared to the suggestion that implied the sensor has not impact on the HVAC system, or this is a memory setting issue.
Although the problem description was the system was trying to trying to turn the heater on, I interpreted that as the system was blowing hot air rather than cool. If you consider that the air temp coming out of the HVAC is determined by what the OAT sensor reads, with a low OAT reading the HVAC will assume the outside temps are low and compensate (at least initially) by biasing the air mix doors towards the heated air side.
No offense to anyone. I just try to answer technical questions with some analytical thought.
Although the problem description was the system was trying to trying to turn the heater on, I interpreted that as the system was blowing hot air rather than cool. If you consider that the air temp coming out of the HVAC is determined by what the OAT sensor reads, with a low OAT reading the HVAC will assume the outside temps are low and compensate (at least initially) by biasing the air mix doors towards the heated air side.
No offense to anyone. I just try to answer technical questions with some analytical thought.
Le Mans Master
Joined: Feb 2006
Posts: 5,267
Likes: 40
From: Phoenix AZ
If the temp sensor is unplugged, it reads 69.
I had one that was missing on my last car. The plug that was still there would get wet and read from 10 to 69 and the AC would not work at the lower temp reading. A brand new sensor from the dealer is $11. It takes about 2 minutes to install. Just get one and go from there.
I had one that was missing on my last car. The plug that was still there would get wet and read from 10 to 69 and the AC would not work at the lower temp reading. A brand new sensor from the dealer is $11. It takes about 2 minutes to install. Just get one and go from there.
Race Director
Joined: May 2000
Posts: 14,542
Likes: 5
Originally Posted by debmwb
I would think that the mis-information is possibly in the statement that "the external termperature sensor has nothing to do with turning on the heater." That statement would imply that the temperature sensor has nothing to do with the climate control system. If the external temperature sensor is indicating that it is 32 degrees to the climate system, then the climate system will try to turn on the heater if the in car temperature was say set at 75.
Here is a picture of the sensor being removed. That's the one I'm talking about:
Drifting
Joined: May 2000
Posts: 1,917
Likes: 3
From: Southern NH
Originally Posted by EHS
Not correct. The heater is controlled by the interior temperature sensor, which could care less what the outside temperature is. If the temperature inside the car is 100 degrees, even if the outside temp is indicating 32, and the setting is 75 degrees, trust me, the heater will not turn on.
Here is a picture of the sensor being removed. That's the one I'm talking about:
Here is a picture of the sensor being removed. That's the one I'm talking about:
I think the point here is that he's in New Mexico, so even if the system adjusts the airflow temp to full cool, the AC can't kick in so all you're getting through the vents is fresh outside air which is about 100*F in that neck of the woods.
Race Director
Joined: May 2000
Posts: 14,542
Likes: 5
Originally Posted by LKGRenegade22
EHS, does that sensor have to placed right there in the skid plate or can it be placed somewhere else? I don't really look forward to taking the parts off to get to that spot again. 
But it probably likes shade and fresh outside air the best.
:
Pro
Joined: Apr 2005
Posts: 651
Likes: 0
From: Littleton NC
Originally Posted by EHS
I don't think it knows where it is, if you don't tell it.
But it probably likes shade and fresh outside air the best.
:
But it probably likes shade and fresh outside air the best.
:Well I will find out because I don't think it will go back to where it used to be unless it can somehow figure out it is in the wrong spot.
