1999 C5 is having problems with air conditioning not cooling, blowing hot air. The car has automatic temp control. Need help. Thanks

 

Most likely the compressor has gone,these A/C systems are sealed and should never need freon added,does the compressor come on? If it's leaking oil around a seal then it's new equipment time,good luck.

 

GM Part # 10248414 is aprox. $10 from the dealer and just plugs in. When it goes bad, you can't get any air conditioning....just hot air.

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.

Once the old sensor is removed, the HVAC defaults to 69* and will let the AC turn on.

 

The AC system is monitored by the DIC and most electronic related issues will throw a DTC. See if you have any DTCs in the HVAC module. If you do,,post them. If there are a LOT of DTCs, clear them and then run the car and the HVAC system and see what ones come back.

READING YOUR Engine Diagnostic Trouble Codes (DTC)

This procedure should be carried out any time you experience a problem with your C5. Most inexpensive store bought aftermarket code readers will ONLY read power train DTC’s. Reading the DTC’s with the C5 built in code reader will allow you to read ALL the modules in the vehicle.

The Diagnostic Display Mode is entered with the following procedure:
1) Turn on the ignition but don't start the engine.
2) Press the RESET button to turn off any warning messages. (i.e. door open, trunk open ect)
3) Press and hold the OPTIONS button
4) While holding OPTIONS, press FUEL button four times within a 10 -second period.

Initially, the on-board diagnostics go into an Automatic Mode which will cycle through each module and shows diagnostic codes in a pre-set sequence: PCM - TCS - RTD - BCM - IPC - RADIO - HVAC - LDCM - RDCM - SCM - RFA. All codes will be displayed for each module. ( i.e. PCM = 4 codes) If none are present in a given module, you will see No More Codes on the display.

There are two types of diagnostic codes, Current and History designated with a letter suffix, “C” or “H”. A current code indicates a malfunction is present in the module displaying data. A history code indicates a problem existed sometime in the last 40 or 50 ignition cycles. When not accompanied by a current code of the same number, it's potential evidence of a previous problem, now resolved, that was not removed by clearing the codes. More likely it's an indication of an intermittent malfunction.

Intermittent codes are the most challenging of the diagnostics. An intermittent code may have happened once, may have happened more than once but is inconsistent or may be happening on a regular basis but not at the time the codes are displayed. History codes can also be caused by a current malfunction in a system that is not operating at the time codes are displayed. An example is the rear window defogger which doesn't operate until the Body Control Module detects engine rpm. For history codes set by a module that does not operate with the key on and engine off, a special diagnostic tool called a Scan Tester is necessary to properly diagnose the malfunction.

Once the system has displayed all modules, it goes into the manual mode which allows selection of each module using combinations of Driver Information Center buttons. Manual mode can also be entered during the automatic sequence by pressing any button except E/M. Once the display shows Manual Diagnostics, select a module by pressing the OPTIONS button to go forward or the TRIP button to go back. Once a module is selected, a code is displayed, and if more than one are present; 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 codes in a given module, press RESET To reset the codes once in manual mode, press and hold RESET until it displays NO CODES Press OPTIONS to go to the next module. Repeat the steps until you have reset the codes in all the computer modules.
NOTE!! Only reset the codes IF you want to - it is NOT necessary to do this. Clearing a code does not repair a problem. You are simply erasing the evidence of it in the module's memory. If you clear the code/s, and extinguish the Check Engine Light, your emissions status ready will NOT allow you to pass an emissions test until you have completed the required driving cycles. There are a few body module DTC’s that if set will prevent the module from operating properly. Once the DTC is cleared, the module will return to full function. This is not true for power train DTCs.

If you have never read and cleared your codes, there will probably be a lot of old history DTCs. It is recommended that you clear your codes and see if any come back during a driving cycle. Those are the ones that you need to concentrate on diagnosing.

Once you have the codes, the next question is: What to do with the information?
First, consult the factory service manual. Any serious C5 Do-It-Yourself owner should invest in the Corvette Service Manual of the appropriate model year. The Service Manual is really a requirement if you want to understand and work on your C5.

These are some very good C5 Diagnostic Trouble Code (DTC) explanation web sites!!! They also explain how to read the DTCs

Here are some very good sites that explain what DTC mean:

http://www.gearchatter.com/viewtopic11755.php

http://www.obd-codes.com/trouble_cod...d-ii-codes.php

Make sure to include the H or C suffix when you post your DTCs!!


IF it been a long time since the system has been serviced, some R-134 can and will leak out. If the LOW Side (suction side pressure) is low out of spec, it will not operate. Some times if its on the verge of being OOS, it will run for a second or two and then the compressor will cut out on low suction pressure.

WALMART sells a r-134 recharge can with a gage. You can recharge the system and monitor the suction pressure. Theres a chart in the service manual that tells you what the pressure should be according to outside temp and outside humidity.

If you do recharge it, MAKE SURE that you only put GAS in the suction side. (charge the system with the can right side UP ) Upside down puts liquid R-134 in the system. That would be bad!!

BC

 

Ok.....we got one bad compressor, and one temperature sensor....

Do I hear a control head.....anyone.......bad control head?

 

anybody try using a compressor from kragen/AUTOZONE?

 

Ill see you one SUN LOAD SENSOR and raise you TWO "AIR DOOR ACTUATORS!

 

Thats EXACTLY what mine is doing right now. Works when I drive, cuts out when I stop.

 

What codes ?

 

no codes

 

Did you actual check the DIC for codes manually ?

 

yes, also used my HPTuners. no codes for AC system

 

What does the A/C light do on the HVAC unit (inside) ? Does the AC light stay a constant yellow light ? or Does it blink ? or go out all together ?

 

You can try this too: http://forums.corvetteforum.com/c5-t...actuators.html

It's free so you don't lose anything.

 

it gos out completly then returns when off idle. As long as Im driving its all good.

 

Sounds like there is something wrong with idle kick up adjustment when you turn on air conditioner.



Once engaged, the compressor clutch will be disengaged for the following conditions:

The throttle position is 100 percent
The A/C pressure is more than 2826 kPa (410 psi)
The A/C pressure is less than 207 kPa (30 psi)
The engine coolant temperature (ECT) is more than 121°C (250°F)
The engine speed is more than 5,500 RPM
The transmission shift
The PCM detects excessive torque load
The PCM detects insufficient idle quality
The PCM detects a hard launch condition

 

Hmmm, I will look further into my tune. Maybe it was something I did. I have been tuning in OLSD with the ac off so I would not have noticed it earlier.

 

Don't know crap on how to tune a car. That will be my next lesson.

I'm good with the mechanics, wiring and general stuff but never got into the whole tuning thing.

I need to learn how, since I plan on going turbo someday.

I have the Repair manual and schematics on DVD. It's good to have. Just got done fixing my bro's A/C problem. Turned out to be a bad relay in the enging compartment fuse box (#36).

 

Good stuff to have, DVD that is. Ill check tomorrow to see wha the low pressure reading is. i can read that in HPTuners. Thanks for all the info.

 

No problem.