Not sure where to start here but here's a summary of whats happened:

Got the car (97 A4) in October, so I haven't used the AC much since I bought it

Drove about 30 mi today to get a tune (efi live) done. Had AC on the whole way. Worked fine.

Worked during tune.

Noticed about halfway home it wasn't blowing cold anymore.

Fans work but AC light just blinks at me now then turns off.

No codes oops, meant no warnings on the dic - ran the codes and got the following (I'm still a pretty new vette owner :bag:
P1545 HC A/C Clutch Relay Control Circuit
P1546 HC A/C Clutch Status Circuit Low Voltage
P1571 H ASR Desired Torque

Fuses ok

Ext temp reads correctly

Neither side gets cold air.


where should I start?


updates:
I've got the dual climate control.

heat works. Guessing this means its not the thermostat or it would probably blow hot at all climate control settings.

codes:
P1545 HC A/C Clutch Relay Control Circuit
P1546 HC A/C Clutch Status Circuit Low Voltage
P1571 H ASR Desired Torque

 

I would start by calling the tuner, maybe he might know something, maybe not, but that is where I would start.

 

Yep, did that. His reply was that nothing he did would have affected the AC.

 

I think my next move would be to do a search in this section and in the tech section. I am not sure but I would bet you could find a trouble shooting and fix it thread. Probably more than one and probably some of the best help you could find anywhere. Some one that knows how might chime in here also. My AC in a car that is not a vette was blowing warm air. I went to advance auto and got a can of freon with the little gauge on it. It fixed it right up.

I am not sure this is your problem since it happened so abruptly.
I would post the exact code in this thread too. In case someone that sees it and knows, would have it right there in front of them to help you with it. Good luck.

 

Thanks. And I did a search and actually came up with alot of info and solutions. Problem is, they're all pretty involved and I'm not sure if there's a logical plan of attack.

 

when the ac lite just blinks and then goes off that usually means the cabin temps isnt warm enough to put AC on. kind of like tying to put the AC on in winter time. also happens when a full reset is done like changing car batteries. it went back to factory setting. try pressing "auto" and make sure its disabled so you can manually set the thermostat.

last case scenario is that the outside ambient temp sensor is bad and its not transferring the information properly to the HVAC controls. but this is only if the outside temp sensor is stuck on a set temp reading. Its a small plastic piece under front panel on passenger side front bumper. youhave to open the access panel to get to it. costs like 9 bucks from the dealer.

 

Hi, First see if the compressor is running with the AC on full and the temps set low. The connector may have been dislodged on it, or one of the pressure switches. Also check to see if your vacuum line that goes to the back of the manifod has been disturbed. It runs from the manifold to the can and vacuum block under the battery box. Also possibility of restriction in liquid line or orifice tube. And possible bad sensors. A very remote possibility that the refridgerant was marginal level and enough leaked out on the drive to shut the system down.
Let us know.

 

your outside air temp sensor maybe be bad.

 

Ok. Also noticed the first time I tried to lock the car from the fob, it didn't work. I had to reset the fob.

If you could unpack the second part of the bold I will give that a shot. I pressed "auto" but I'm not following you after that.

I'll do a search to manually set the tstat.

Thanks!

edit: heat works. Guessing this means its not the thermostat or it would probably blow hot at all climate control settings.

 

Outside air temp appears to be correct. It displays the right temp.

Compressor does not turn on. The AC light blinks 6 times then turns off. This is the part I dont want to get into, but if the above "reset" doesn't work, guess I'll have to. Thanks.

 

codes:
P1545 HC A/C Clutch Relay Control Circuit
P1546 HC A/C Clutch Status Circuit Low Voltage
P1571 H ASR Desired Torque

 

Hi, below is a description of your system. from the codes listed it seems the compressor is not getting the voltage neccessary to engage it.
Most probable is disengaged connnector somewhere in the circuit, or possible a bad relay. I believe the relay and the fuse are located in the engine bay fuse block. But look for a bad connection, because that would make sense, if the tuner moved something around while working possibly near the #7 plug which is hard to access.
Read Below
+++++++++++++++++++++++++++++++++
Circuit Operation
The compressor for the air conditioning system is belt-driven by the engine through the A/C Compressor Clutch. The Powertrain Control Module (PCM) controls the A/C Compressor depending on the HVAC Programmer Module mode and temperature settings. The PCM controls the A/C Compressor Clutch by activating the A/C CLU micro relay 34.

When the PCM receives a A/C request from the HVAC Programmer Module through circuit 762, it activates the A/C CLU micro relay 34 through circuit 459. The battery voltage is applied from the A/C mini fuse 24 and A/C micro relay 34 to the A/C Compressor Clutch through circuit 59. Circuit 59 also carries the A/C Compressor status to the PCM. The A/C Diode prevents current flow that could damage A/C Compressor Clutch components. The A/C Compressor Clutch is grounded through circuit 150 to Splice Pack #100, SP100.

The PCM uses the A/C Refrigerant Pressure Sensor to control refrigerant pressure. If the refrigerant pressure is too high (i.e., could cause engine overheating), the PCM disengages the A/C Compressor Clutch. The A/C Refrigerant Pressure Sensor sends refrigerant pressure data to the PCM through circuit 380. Circuit 407 supplies the A/C Refrigerant Pressure Sensor with ground voltage, and circuit 474 supplies 5V reference voltage.

 

Below is a diagnostic that may help you locate the open or bad connection
++++++++++++++++++++++++++++++++++
HVAC Compressor Clutch Does Not Engage
A/C Compressor Clutch Does Not Engage <<C60>> Step
Action
Value(s)
Yes No

DEFINITION: A/C compressor clutch will not engage when an A/C request has been made and no Powertrain DTC are set.

1
Were you sent here from the HVAC Blower Controls System Check (C60)?
--
Go to Step 2
Go to HVAC Blower Controls System Check (C60)

2
Remove the A/C CLU Micro Relay #34.
Disconnect the A/C compressor clutch connector.
Using a DMM, measure for continuity between terminal A of the A/C compressor clutch connector and ground.
Is the resistance infinite?
--
Go to Step 4
Go to Step 3

3
Locate and repair a short to ground in CKT 59 between the underhood electrical center and the A/C compressor clutch connector.

Is the repair complete?
--
Go to HVAC Blower Controls System Check (C60)
--

4
A/C CLU Micro Relay #34 still removed.
A/C compressor clutch connector still disconnected.
Connect a fused jumper between terminal 30 and terminal 87 of the underhood electrical center which is used for the A/C CLU Micro Relay #34.
Using a DMM, measure the voltage at the A/C compressor clutch connector terminal A.
Is the voltage within the specified values?
10.0-14.0V
Go to Step 6
Go to Step 5

5
Locate and repair an open or a high resistance in CKT 59.

Is the repair complete?
--
Go to HVAC Blower Controls System Check (C60)
--

6
Using a DMM, measure for continuity between terminal B of the A/C compressor clutch connector and ground.

Is the CKT 150 continuous to ground?
--
Go to Step 8
Go to Step 7

7
Locate and repair an open or a high resistance in CKT 150.

Is the repair complete?
--
Go to HVAC Blower Controls System Check (C60)
--

8
Disconnect the powertrain control module (PCM) connector C1.
Reinstall the A/C CLU Micro Relay #34.
Connect a fused jumper between the PCM connector C1 terminal 39 and ground.
Turn the ignition switch to the ON position.
Using a DMM, measure the voltage at the A/C compressor clutch connector terminal A.
Is the voltage within the specified values?
10.0-14.0V
Go to Step 9
Go to Step 10

9
Remove the fused jumper from the PCM connector C1 terminal 39 and ground.
Reconnect the A/C compressor clutch connector.
Reinstall the fused jumper between the PCM connector C1 terminal 39 and ground.
Turn the ignition switch to the ON position.
Does the A/C compressor clutch engage?
--
Go to System Performance Test
Go to Step 16

10
Turn the ignition switch to the OFF position.
Remove the A/C CLU Micro Relay #34.
Using a DMM, measure for continuity between the PCM connector C1 terminal 39 and terminal 88 of the underhood electrical center which is used for the A/C CLU Micro Relay #34.
Is CKT 459 continuous between these two terminals?
--
Go to Step 12
Go to Step 11

11
Locate and repair an open or a high resistance in CKT 459.

Is the repair complete?
--
Go to HVAC Blower Controls System Check (C60)
--

12
Replace the A/C CLU Mini Relay #34 and retest the A/C system.

Does replacing the A/C CLU Mini Relay #34 correct the concern?
--
Go to HVAC Blower Controls System Check (C60)
Go to Step 13

13
Disconnect the HVAC control head connector C1.
Connect a DMM between the PCM connector C1 terminal 47 and the HVAC control head connector C1 terminal B.
Measure CKT 762 for continuity between these two connectors.
Is CKT 762 continuous?
--
Go to Step 15
Go to Step 14

14
Locate and repair an open or a high resistance in CKT 762.

Is the repair complete?
--
Go to HVAC Blower Controls System Check (C60)
--

15
Connect a DMM between the PCM connector C1 terminal 47 and ground.
Measure CKT 762 for continuity to ground.
Is CKT 762 continuous to ground?
--
Go to Step 16
Go to Step 17

16
Locate and repair a short to ground in CKT 762.

Is the repair complete?
--
Go to HVAC Blower Controls System Check (C60)
--

17
Disconnect the DMM.
Reconnect all connectors back to their respective modules.
Install the scan tool to the diagnostic link connector.
Start the engine and allow it to idle in Park.
Select the area of the scan tool which will read HVAC button output status.
Depress the A/C button on/off several times.
Does the scan tool read the A/C request being sent by the HVAC control head?
--
Go to Step 18
Go to Step 19

18
Replace the PCM.

Is the repair complete?
--
Go to HVAC Blower Controls System Check (C60)
--

19
Replace the HVAC control head.

Is the repair complete?
--
Go to HVAC Blower Controls System Check (C60)
--

 

Its blowing fuse 24. Any idea why?

 

The most likely thing to look for is a shorted wire. trace down the wires back from the compressor and look for a bare spot. If the tuner changed your plugs, look in the area of the #7 plug for wires running through that area that might have been moved and allowed to lay on a hot engine or manifold. Also look below the battery box for acid damage to the harness. It could also be a bad ac clutch,but you would have to follow the diagnostic to check it. An easy but unorthodox way to test the compressor is to disconnect the connector from the terminals on the ac compressor, run a fused 12v hot wire and ground wire to the terminals and see if the clutch engages or the fuse on the fused line blows. If the clutch engages it is good, and you have a short in the circuit, if the fuse blows, you need a new clutch,or complete compressor if you can't replace the clutch yourself and can not find someone to do it. Also if the clutch engages, and you don't have to run the engine to see it, it will click in noticebly, see if you can spin the compressor by hand, you should be able to rotate it a bit to see if it is not seized, loosen the belt tension a bit to do this. Or after you hook upthe jump wires make sure they are out of the way of anything spinning and run the engine for a minute and see if the compressor spins, if the belt squeals and the compressor doesn't spin, shut it off and get a new one.
Rule out a shorted wire, or a shorted clutch, and let us know.
From the fact that somebody was working in there,
i'd bet on a shorted wire laying on a hot surface or cut by a belt.
Good Luck

 

Hi There,
I would start by checking for air pressure on the low & high pressure lines at the schrader valve(black plastic cap) by using a common screw driver.If there is no pressure releasing on either side. Then the system is empty or low on freon.(leaked out some place).Then a/c should be blowing hot air.If thats the case then take the car to have the system serviced with freon. If your a/c system will not accept the re-charge then you need to replace the a/c compressor & clutch, dryer(filter).The technician should be able to tell you where it was leaking from. Usually leaks from an o-ring,but could have leaked at the compressor. Which is where mine was leaking from. ( most expensive item in the system) Note:The pcm commands the a/c relay.If you are low on freon & the compressor cycles on & off too much.The pcm will display the codes you listed and disable the a/c clutch relay by blowing the fuse.This will prevent compressor damage.
Been there & done this: compressor, clutch, dryer and changed all the o-rings in the system. Took the car back to be cleaned & charged. Ops ch.ok no leaks. I did this myself on my other sports car, but not on my 01 vette
I hope this helps you. Keep us posted.
robsc501

 

Hi, A leaked out system should not blow the fuse. It will shut the system down,but not blow the fuse. He may need a compressor but it would be from a shorted clutch with the symptoms he described. Of course if the compressor turns out to be the culprit, he will need the evacuate, flush, clean, replace the compressor, orifice tube, accumulator/dryer, and recharge.

 

Guys, this problem is the subject of multiple threads. We've tied it down to a problem in the compressor. When he pulls the connector it stops blowing the fuse. Looks like a compressor snag.

http://forums.corvetteforum.com/show....php?t=2046356

 

This happened to me today...right after i had a quick wide open throttle run....

you said that you just had it dyno'd...
The long thread posted above...that guy just had this dyno'd too...

Wide open thottle runs with AC leading to failures?