A/C won't come on??
Thread Starter
Instructor
Joined: Oct 2009
Posts: 249
Likes: 0
From: FL
A/C won't come on??
I have a 1999 with the thermostatically controlled a/c unit. Had been working fine, but today won't power on at all. Any ideas?? I have not had any codes on the DIC, but if I need to pull codes could you refresh my memory on how to do that?
Thanks in advance-
Lonnie
Thanks in advance-
Lonnie
Burning Brakes
Joined: Jan 2006
Posts: 1,170
Likes: 27
From: Magnolia Greens NC
try this first...
Did you check to see if the fuse that protects the AC circuit is tripped? If it's OK, then
Your problem could be faulty outside air temp sensor which is a
GM Part # 10248414 i.... aprox. $10 from the dealer and just plugs in.
Once the old sensor is removed, the HVAC defaults to 69* and will let the AC turn on.
The sensor is located on the right (passenger) side of the car, on the outside of the frame rail in the very front by the headlight.
It is held onto the mounting hole on the frame by a plastic push-in clip.
Just pull the clip out of the hole on the frame, release the plug for the wire (the plug has a release clip, pry up on the clip and the plug will release).
Then just put in the new one and you will be in business - it takes a few minutes of driving for the sensor to start reading the outside temp - you have to be moving.
The sensors are either resistance temperature detectors (RTD's) or Thermistors. The resistance of the sensor changes with the temperature.
If you have any corrosion in any of the associated connectors it will increase the resistance that the climate controls is reading.
The resistance across the two sensor wires could be almost infinity,
in that case your display would read a low temp.
Your problem could be faulty outside air temp sensor which is a
GM Part # 10248414 i.... aprox. $10 from the dealer and just plugs in.
Once the old sensor is removed, the HVAC defaults to 69* and will let the AC turn on.
The sensor is located on the right (passenger) side of the car, on the outside of the frame rail in the very front by the headlight.
It is held onto the mounting hole on the frame by a plastic push-in clip.
Just pull the clip out of the hole on the frame, release the plug for the wire (the plug has a release clip, pry up on the clip and the plug will release).
Then just put in the new one and you will be in business - it takes a few minutes of driving for the sensor to start reading the outside temp - you have to be moving.
The sensors are either resistance temperature detectors (RTD's) or Thermistors. The resistance of the sensor changes with the temperature.
If you have any corrosion in any of the associated connectors it will increase the resistance that the climate controls is reading.
The resistance across the two sensor wires could be almost infinity,
in that case your display would read a low temp.
Last edited by trussme; Jul 14, 2010 at 02:12 PM.
Burning Brakes
Joined: Jan 2006
Posts: 1,170
Likes: 27
From: Magnolia Greens NC
now here's how to pull codes...if the above did not solve your problem
with the key in the on position, but the engine not running
push and release the reset button until all messages cleared
next push and HOLD button #4
next push and release button #1 four times while holding button #4
When first engaged the on-board diagnostics go into an "automatic" mode which shows all parameters: PCM-TCS-RTD-BCM-IPC-radio-HVAC-LDCM-RDCM-SCM-RFA. If there are no problems, you will see "no more codes" on the ICP display. The computer will show two kinds of codes, "current" and "history," designated "C" or "H". A current code indicates a malfunction is present in the system whose module is displaying data. A history code indicates a past problem. When the screen displays "manual diagnostics," select the desired module by pressing the "options" button to go forward or the "trip" button to go back. Press "gages" to go forward or "fuel" to go back. To exit the diagnostic mode at any time, press "E/M".
If you want to erase or "clear" codes, press .""reset
push and release the reset button until all messages cleared
next push and HOLD button #4
next push and release button #1 four times while holding button #4
When first engaged the on-board diagnostics go into an "automatic" mode which shows all parameters: PCM-TCS-RTD-BCM-IPC-radio-HVAC-LDCM-RDCM-SCM-RFA. If there are no problems, you will see "no more codes" on the ICP display. The computer will show two kinds of codes, "current" and "history," designated "C" or "H". A current code indicates a malfunction is present in the system whose module is displaying data. A history code indicates a past problem. When the screen displays "manual diagnostics," select the desired module by pressing the "options" button to go forward or the "trip" button to go back. Press "gages" to go forward or "fuel" to go back. To exit the diagnostic mode at any time, press "E/M".
If you want to erase or "clear" codes, press .""reset
Thread Starter
Instructor
Joined: Oct 2009
Posts: 249
Likes: 0
From: FL
Now that I look closer, when car is moving cold air comes from vents, but it seems blower motor is not working. Is there a fuse that might be tripped or relay I should check?
Lights are working normally. although they have always been dim.
Lights are working normally. although they have always been dim.
Le Mans Master
Joined: Nov 2005
Posts: 6,993
Likes: 25
The drains (aka "udders") for the AC get clogged and the water backs up where the fan is and they get rusty, you can check the fuses but see if it's wet on the passenger side and check the "udders". Bet your fan is funky.
Melting Slicks
Joined: Oct 2007
Posts: 2,383
Likes: 13
From: Kinston North Carolina
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Top 10 Corvette Engines RANKED by Peak Torque (70+ Years of Muscle!)
Joe Kucinski
Corvette ZR1X Will Be Pacing the Indy 500, And Could Probably Race, Too!
Verdad Gallardo
Top 10 Corvettes Coming to Mecum Indy 2026!
Brett Foote
Top 10 C9 Corvette MUST-HAVES to Fix These C8 Generation Flaws!
Michael S. Palmer
10 Revolutionary 'Corvette Firsts' Most People Don't Know
Joe Kucinski
