A/C not cold
Thread Starter
Navigator
Joined: Nov 2019
Posts: 9
Likes: 1
A/C not cold
Hi, any help would be appreciated.
my 2016 zo6 is not blowing cold air.
i have done the following, drained and recharged ac system. - system was full and no leaks found.
what I did find was that I was told the pressures went up when I raised the rpm. The pressure is supposed to drop.
i was told that I need either a compressor or an expansion valve. They suggest the expansion valve is the problem .
my 2016 zo6 is not blowing cold air.
i have done the following, drained and recharged ac system. - system was full and no leaks found.
what I did find was that I was told the pressures went up when I raised the rpm. The pressure is supposed to drop.
i was told that I need either a compressor or an expansion valve. They suggest the expansion valve is the problem .
Instructor
Joined: Apr 2019
Posts: 152
Likes: 16
From: Aberdeen, MD
Had this exact same problem happen to me about 2 weeks ago. Took it to mechanic and just like you found no leaks or anything, pressures raised just like yours, and no recharge needed.
Get this/Try this: Mechanic took a water hose with a sprayer nozzle and shot it up thru the front of my grille with the car running meanwhile I was in the car revving the throttle up and down.
We did this repeatedly for about 3 minutes with him walking back and forth in front of the car spraying the water deep up inside the lower front grille. Do you know my AC started blowing ice cold!!!
He said sometimes in the fall that leaves and debris block the AC cooler (im assuming there is a small cooling ventilator specifically for the AC) and if it gets blocked it cant breathe and mechanic told me it needs to be clear at all times for the AC to blow cold air. I just shook my head at this and drove off free of charge and my AC works just fine now.
Get this/Try this: Mechanic took a water hose with a sprayer nozzle and shot it up thru the front of my grille with the car running meanwhile I was in the car revving the throttle up and down.
We did this repeatedly for about 3 minutes with him walking back and forth in front of the car spraying the water deep up inside the lower front grille. Do you know my AC started blowing ice cold!!!
He said sometimes in the fall that leaves and debris block the AC cooler (im assuming there is a small cooling ventilator specifically for the AC) and if it gets blocked it cant breathe and mechanic told me it needs to be clear at all times for the AC to blow cold air. I just shook my head at this and drove off free of charge and my AC works just fine now.
Safety Car
Joined: Dec 2012
Posts: 3,835
Likes: 1,853
From: St. Louis Metro East IL
- Does the compressor clutch engage? You can often hear a click or see the compressor hub rotate or not rotate depending on HVAC mode.
- Are you using an A/C gauge manifold? With compressor not engaged, both pressure taps will be at the same pressure, but with compressor running the high pressure tap between the compressor and condensor will be higher than the low pressure tap between the heater and compressor. The pressure differential should increase with rpms.
- You emptied and recharged the refrigerant. Did you pull a vacuum before putting refrigerant back in? Or did you open to atmosphere and get the system full of air before adding refrigerant? Air is a lousy refrigerant.
- The spec for most A/C systems is that "cold" air is 20 deg below ambient - so don't expect 40 deg air from the vents when it is 100 deg.
- Will the system change air outlets (floor, dash, defrost)? Does temperature respond in heat? Air flow doors need to work too. If stuck in full heat mode, it won't matter what the A/C compressor is doing.
- And as noted above - the condenser needs to have airflow to reject heat efficiently.
GL
Ron
- Are you using an A/C gauge manifold? With compressor not engaged, both pressure taps will be at the same pressure, but with compressor running the high pressure tap between the compressor and condensor will be higher than the low pressure tap between the heater and compressor. The pressure differential should increase with rpms.
- You emptied and recharged the refrigerant. Did you pull a vacuum before putting refrigerant back in? Or did you open to atmosphere and get the system full of air before adding refrigerant? Air is a lousy refrigerant.
- The spec for most A/C systems is that "cold" air is 20 deg below ambient - so don't expect 40 deg air from the vents when it is 100 deg.
- Will the system change air outlets (floor, dash, defrost)? Does temperature respond in heat? Air flow doors need to work too. If stuck in full heat mode, it won't matter what the A/C compressor is doing.
- And as noted above - the condenser needs to have airflow to reject heat efficiently.
GL
Ron
Last edited by RonC7; Nov 5, 2019 at 01:12 PM.
Thread Starter
Navigator
Joined: Nov 2019
Posts: 9
Likes: 1
- Does the compressor clutch engage? You can often hear a click or see the compressor hub rotate or not rotate depending on HVAC mode.
- Are you using an A/C gauge manifold? With compressor not engaged, both pressure taps will be at the same pressure, but with compressor running the high pressure tap between the compressor and condensor will be higher than the low pressure tap between the heater and compressor. The pressure differential should increase with rpms.
- You emptied and recharged the refrigerant. Did you pull a vacuum before putting refrigerant back in? Or did you open to atmosphere and get the system full of air before adding refrigerant? Air is a lousy refrigerant.
- The spec for most A/C systems is that "cold" air is 20 deg below ambient - so don't expect 40 deg air from the vents when it is 100 deg.
- Will the system change air outlets (floor, dash, defrost)? Does temperature respond in heat? Air flow doors need to work too. If stuck in full heat mode, it won't matter what the A/C compressor is doing.
- And as noted above - the condenser needs to have airflow to reject heat efficiently.
GL
Ron
- Are you using an A/C gauge manifold? With compressor not engaged, both pressure taps will be at the same pressure, but with compressor running the high pressure tap between the compressor and condensor will be higher than the low pressure tap between the heater and compressor. The pressure differential should increase with rpms.
- You emptied and recharged the refrigerant. Did you pull a vacuum before putting refrigerant back in? Or did you open to atmosphere and get the system full of air before adding refrigerant? Air is a lousy refrigerant.
- The spec for most A/C systems is that "cold" air is 20 deg below ambient - so don't expect 40 deg air from the vents when it is 100 deg.
- Will the system change air outlets (floor, dash, defrost)? Does temperature respond in heat? Air flow doors need to work too. If stuck in full heat mode, it won't matter what the A/C compressor is doing.
- And as noted above - the condenser needs to have airflow to reject heat efficiently.
GL
Ron
ill try to answer all your questions,
the ac clutch is engaging.
i worked at a shop and the head tech looked at it quickly for me.
they attached it to an ac machine and did pull a vacuum before recharging.
the ac machine has gauges on it and when I increased the rpm’s while it was attached to the machine and after the recharge. One side the pressure is supposed to go up and the other side should drop but in my case both sides went up.
the tech that looked at it and told me it is probably a bad expansion valve or possibly a bad compressor has more than 40 years experience and he gets all the jobs that others can’t figure out.
he said it is more than likely the expansion valve not closing the system.
oh and the heat works, the ac works ever so slightly when it is on but no where close to being cold.
all vents and defrost seems to be working properly.
the cool air when ac is on gets a little warmer as you raise the rpms.
jay
Safety Car
Joined: Dec 2012
Posts: 3,835
Likes: 1,853
From: St. Louis Metro East IL
OK. Yeah, the expansion valve is likely not working. Its function is to restrict the liquid refrigerant flow so it flashes to vapor and gets cold. The cold vapor flows into the a/c coils and cools the air flowing through the car heater. So - if it fail to restrict flow, there is no pressure drop from high side to low side. Compressor failure would also explain the problem.
If you had an experienced mechanic diagnose your system then have him go ahead and fix it.
Ron
If you had an experienced mechanic diagnose your system then have him go ahead and fix it.
Ron
1st Gear
Joined: Nov 2020
Posts: 1
Likes: 1
- Does the compressor clutch engage? You can often hear a click or see the compressor hub rotate or not rotate depending on HVAC mode.
- Are you using an A/C gauge manifold? With compressor not engaged, both pressure taps will be at the same pressure, but with compressor running the high pressure tap between the compressor and condensor will be higher than the low pressure tap between the heater and compressor. The pressure differential should increase with rpms.
- You emptied and recharged the refrigerant. Did you pull a vacuum before putting refrigerant back in? Or did you open to atmosphere and get the system full of air before adding refrigerant? Air is a lousy refrigerant.
- The spec for most A/C systems is that "cold" air is 20 deg below ambient - so don't expect 40 deg air from the vents when it is 100 deg.
- Will the system change air outlets (floor, dash, defrost)? Does temperature respond in heat? Air flow doors need to work too. If stuck in full heat mode, it won't matter what the A/C compressor is doing.
- And as noted above - the condenser needs to have airflow to reject heat efficiently.
GL
Ron
- Are you using an A/C gauge manifold? With compressor not engaged, both pressure taps will be at the same pressure, but with compressor running the high pressure tap between the compressor and condensor will be higher than the low pressure tap between the heater and compressor. The pressure differential should increase with rpms.
- You emptied and recharged the refrigerant. Did you pull a vacuum before putting refrigerant back in? Or did you open to atmosphere and get the system full of air before adding refrigerant? Air is a lousy refrigerant.
- The spec for most A/C systems is that "cold" air is 20 deg below ambient - so don't expect 40 deg air from the vents when it is 100 deg.
- Will the system change air outlets (floor, dash, defrost)? Does temperature respond in heat? Air flow doors need to work too. If stuck in full heat mode, it won't matter what the A/C compressor is doing.
- And as noted above - the condenser needs to have airflow to reject heat efficiently.
GL
Ron
You were spot on with this listing. My C7's AC did not work at all. Went to the dealer, and they charged me $200 for a diagnosis. The verdict was that I needed a new Compressor, which would cost me close to $2000. I gracefully declined as it is late in the summer anyway. A few days later I switched the air outlet to "floor only" and all of a sudden I feel cold air !!! I kept switching the air outlet back and forth through the settings, and for a few weeks now, the system has worked like a charm. I guess switching the air outlet between different positions freed up an air door that was stuck somehow, and that was all it needed.
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