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The AC on my 99 C 5 has stopped blowing cold. Last Fall I noticed that the compressor sounded a bit louder than normal but still worked fine so maybe the compressor is at fault. I usually do my own repairs but this seems beyond me so wondering where is the best place to have it repaired, dealer or independent repair shop. I am leaning towards a dealer since they have at least theoretically worked on Corvettes before and independent (we do it all) repair shops scare me.
Car is currently in connecticut.
Would not take it to a dealer since your car is older than the Techs that will be working on it !!... and they are CLUELESS are far as diagnostics !!...find a shop that specializes in AC repair !!...you may just need some Freon !!
The AC on my 99 C 5 has stopped blowing cold. Last Fall I noticed that the compressor sounded a bit louder than normal but still worked fine so maybe the compressor is at fault. I usually do my own repairs but this seems beyond me so wondering where is the best place to have it repaired, dealer or independent repair shop. I am leaning towards a dealer since they have at least theoretically worked on Corvettes before and independent (we do it all) repair shops scare me.
Car is currently in connecticut.
Testing instructions specific to a 1999 model year car
1. If the engine is at operating temperature, allow the engine to cool to room temperature. 2. Ensure that the ignition key is in the OFF position. 3. Connect an R-134a manifold gage set to the low side and high side service ports on the vehicle refrigerant system. 4. Check the low and high side pressures. The low and high side pressure readings should be almost equal to each other once the system has come to rest. Are both the low and high side pressures above the specified value >>>345 kPa (50 psi) ? IF NOT (50 psi), then system is LOW...
1. Start the engine and allow the engine to idle. 2. Depress the mode control button until the UPPER position is displayed. 3. Turn the A/C ON by depressing the A/C button on the HVAC control head. Does the compressor clutch engage?
1. Accurately measure and record both the ambient air humidity level and temperature. (These figures will be used later., see performance test table below) 2. The engine still idling in PARK. 3. Install a precision thermometer into the I/P center air outlet. 4. Set the HVAC control head to the following positions: • A/C button to ON • Temperature control to full cold • Mode control button to UPPER (I/P outlets) • Blower speed to maximum high 5. Elevate and maintain the engine speed at 1000 RPM. 6. Allow the low and high side pressure readings to stabilize, if necessary (Stabilization usually requires 2-3 minutes.) 7. Record the low and high side pressure readings. 8. Compare the low and high side pressures to the A/C System Pressure -- Zone Classification Chart.
Do both the low and high side pressures fall within Zone A on the classification chart? OR... Do both the low and high side pressures fall within Zone B on the classification chart? OR... Do both the low and high side pressures fall within Zone C on the classification chart? OR Do both the low and high side pressures fall within Zone D on the classification chart?
1999 AC Chart
Depending on your results, zone A, B, C or D there are different troubleshooting procedure depending on zone...
Testing instructions specific to a 1999 model year car
1. If the engine is at operating temperature, allow the engine to cool to room temperature. 2. Ensure that the ignition key is in the OFF position. 3. Connect an R-134a manifold gage set to the low side and high side service ports on the vehicle refrigerant system. 4. Check the low and high side pressures. The low and high side pressure readings should be almost equal to each other once the system has come to rest. Are both the low and high side pressures above the specified value >>>345 kPa (50 psi) ? IF NOT (50 psi), then system is LOW...
1. Start the engine and allow the engine to idle. 2. Depress the mode control button until the UPPER position is displayed. 3. Turn the A/C ON by depressing the A/C button on the HVAC control head. Does the compressor clutch engage?
1. Accurately measure and record both the ambient air humidity level and temperature. (These figures will be used later., see performance test table below) 2. The engine still idling in PARK. 3. Install a precision thermometer into the I/P center air outlet. 4. Set the HVAC control head to the following positions: • A/C button to ON • Temperature control to full cold • Mode control button to UPPER (I/P outlets) • Blower speed to maximum high 5. Elevate and maintain the engine speed at 1000 RPM. 6. Allow the low and high side pressure readings to stabilize, if necessary (Stabilization usually requires 2-3 minutes.) 7. Record the low and high side pressure readings. 8. Compare the low and high side pressures to the A/C System Pressure -- Zone Classification Chart.
Do both the low and high side pressures fall within Zone A on the classification chart? OR... Do both the low and high side pressures fall within Zone B on the classification chart? OR... Do both the low and high side pressures fall within Zone C on the classification chart? OR Do both the low and high side pressures fall within Zone D on the classification chart?
1999 AC Chart
Depending on your results, zone A, B, C or D there are different troubleshooting procedure depending on zone...
Cheers, Goose
In step 4 your “static pressure” should be roughly equal to the outside air temp...if temp is 90 F. the static pressure should be roughly 90 PSI !!
Watch the first few minutes of this video...we call it static or rest pressure !! [/QUOTE
Very informative video, thanks for sharing.
But as I posted>>> Testing instructions specific to a 1999 model year car can you please clarify> In step 4 your “static pressure”?
I don’t know what you want me to clarify ??...this is a “general” rule regarding rest or static pressure...I really don’t follow these “factory” flow charts anyway !!...most are confusing and will lead you down the wrong path...if you have an understanding of how these various electrical circuits operate you can diagnose a 99 Corvette or a 2012 Honda Civic !!
Do you have an a/c gauge set and does the compressor still run when you turn on the a/c? If the compressor does run, is the suction line cool? Have you had the a/c serviced in previous years? If you have gages and they read little to no pressure, you have lost your refrigerant charge.
best case scenario for a simple do it yourself is the system still runs and the suction line is at least a little cooler that ambient. It’s a little troubling that you believe you hear the compressor more than in the past but compressors can get noisier when running under low refrigerant charge. So if the compressor runs and cools a bit, you can try adding half a can (6 ounces) of r134a and see if it improves. If it takes the half can, cools, but is still noisy, you might want to stop there.
If the system does not run this simple DIY won’t work because you can’t put the half can in.
C 5 air conditioning
