AC Lights Blink At Startup (No AC)

[92BlackVette]

My AC lights on the front control panel are blinking at startup and they go off after a couple of minutes. The AC no longer blows cold. The fans do turn and I feel air, warm air.....

This happened over the weekend so I haven't had a chance to crack open my FSM or even the hood for that matter. I thought it was cool the lights blink when there is a problem but what do they mean. I will check the pressure of the system tonight. I can't tell if the compressor is engaging.

Facts:

I had my system charged and vacuumed Friday. The controls and the AC was perfect on Friday, Saturday, however Sunday this current issue was the case. The AC sensor switch was leaking and replaced, the drier was also swapped. Any ideas of the AC blinking lights?

I will complete a full diagnosis when I get home just wondering about the blinking AC lights for now.

Thanks!;help

 

[bucket]

My AC lights on the front control panel are blinking at startup and they go off after a couple of minutes. The AC no longer blows cold. The fans do turn and I feel air, warm air.....

This happened over the weekend so I haven't had a chance to crack open my FSM or even the hood for that matter. I thought it was cool the lights blink when there is a problem but what do they mean. I will check the pressure of the system tonight. I can't tell if the compressor is engaging.

Facts:

I had my system charged and vacuumed Friday. The controls and the AC was perfect on Friday, Saturday, however Sunday this current issue was the case. The AC sensor switch was leaking and replaced, the drier was also swapped. Any ideas of the AC blinking lights?

I will complete a full diagnosis when I get home just wondering about the blinking AC lights for now.

Thanks!;help

the good news is that you have already paid for it to be fixed the bad news is you get to go back to the same guy..

 

[Curious George]

The blinking light means the system has an issue (obviously). It sounds like your refridgerant has leaked out again. There is a way to go into the AC programmer and retrieve codes. Look at your FSM for this.

CG

 

[Schrade]

My AC lights on the front control panel are blinking at startup and they go off after a couple of minutes. The AC no longer blows cold. The fans do turn and I feel air, warm air.....

This happened over the weekend so I haven't had a chance to crack open my FSM or even the hood for that matter. I thought it was cool the lights blink when there is a problem but what do they mean. I will check the pressure of the system tonight. I can't tell if the compressor is engaging.

Facts:

I had my system charged and vacuumed Friday. The controls and the AC was perfect on Friday, Saturday, however Sunday this current issue was the case. The AC sensor switch was leaking and replaced, the drier was also swapped. Any ideas of the AC blinking lights?

I will complete a full diagnosis when I get home just wondering about the blinking AC lights for now.

Thanks!;help

Check the FSM like CG said, for pulling diagnostics. Then go to Advance / Zone, buy a Mickey Mouse guage ($15), and get some pressure readings.

The consumer-guages (MM-type) are really good only for RELATIVE readings, not absolute readings. Like motor-off pressure, motor (and A/C system on) pressure, and before-and-after 1 can recharge pressure, etc.

 

[92BlackVette]

I popped the hood during lunch and checked my connections that I opened as a result of replacing the AC sensor switch on the high pressure side....no oil around the fittings or on the rail. I also checked the drier and the rail looks good there too, these lines are all oil free. So I guess this means I will have to check the pressure when I get home. Maybe it was a fast leak.

To be specific:

The light under the AC button you choose for AC settings blinks, like for example the off button blinks, and after a couple of minutes, the light that was blinking goes solid (normal). This is the same for all buttons on the control panel from the first couple of minutes.

 

[Curious George]

I notice you have a '92. That means you "had / have" R-12 (Freon) unless it was converted. When the recharge was done, did they put R-12 back in or R-134? If they put R-134 in you may have some real issues brewing if the conversion was not done correctly.

CG

 

[dogfish246]

I forget how/which butons, but if you hold the up and down arrow (I think) together on the climate control the screen will come up with a trouble code... this will help you figure out why the light is blinking...

Good Luck!:cool

 

[Curious George]

What is up with the red text??

CG

 

[92BlackVette]

So here is where I am at:
I have checked for a blown A/C - Gauge fuse
Loose/disconnected AC wire connector
Checked blower for fan operation
Engine cooling fan operation
Compressor isn't seized
*********
Next Steps--->I am working on checking on the clutch operation, and codes 66,67,68,69


Concerning issues:
My Mickey Mouse gauge says there is 150 LBs of pressure on the low side! On or Off

My range on the low side should be between: 29 to 42 PSIG, WTF!

 

[toptechx6]

So here is where I am at:
I have checked for a blown A/C - Gauge fuse
Loose/disconnected AC wire connector
Checked blower for fan operation
Engine cooling fan operation
Compressor isn't seized
*********
Next Steps--->I am working on checking on the clutch operation, and codes 66,67,68,69


Concerning issues:
My Mickey Mouse gauge says there is 150 LBs of pressure on the low side! On or Off

My range on the low side should be between: 29 to 42 PSIG, WTF!

If the compressor is not running system pressure will equalize, so the low side will be above 42 PSI, but it should not be 150. There are no codes above 10 for the climate control so I think you have entered Parameters by mistake.

See the procedure copied below. NOTE: Pressing the up or down arrow key after initially entering diagnostic mode enters the Parameters view.

I would try resetting the control head first, with the ignition key off, disconnect the negative battery cable for about one minute then reconnect. See if your symptoms or codes return after the reset by using the procedure below.


If your 1990 to 1996 Vette is equipped with RPO C68 (electronic climate control) you can read the HVAC system diagnostic codes from your climate control unit. To enter diagnostic mode, push and hold the fan up arrow and down arrow at the same time until the LCD shows -00 You are now in diagnostic mode, see the list of faults below.


If your 1990 to 1996 Vette is equipped with RPO C68 (electronic climate control) you can read the HVAC system diagnostic codes from your climate control unit. To enter diagnostic mode, push and hold the fan up arrow and down arrow at the same time until the LCD shows -00 You are now in diagnostic mode, see the list of faults below. Stop here to read codes.

System Faults

(one of these will be set if your air conditioning controls have an LED flashing)


00=No Faults

01= Temp Door Motor Circuit Fault

02= Temp Door Motor Circuit Fault

03 = Ambient Sensor Open

04 = Ambient Sensor Short

05 = In-Vehicle Temp Sensor Open

06 = In-Vehicle Temp Sensor Short

07 = Solar Load Sensor Open

08 = Solar Load Sensor Short

09 = Low Freon Detected

10 = UART Failure

As with PCM or CCM diagnostic trouble codes each of these has a systematic troubleshooting procedure detailed in the Factory Service Manual which should be followed to correct the problem.
Solutions to some such as Low Freon detected are strait forward, check the refrigerant charge. The ambient sensor is mounted in the opening at the front of the car leading to the radiator, if it becomes disconnected it will set fault 03.
Once a fault is repaired you will need to disconnect the battery negative cable for about one minute to clear the code, then reconnect the cable and try the system to see if it functions correctly, if the led is flashing the system will NOT resume normal operation.

You may also select any parameter monitored by the climate control using the up and down arrows. To see the value for that parameter, press the fan "auto" button.
The values may assist you with troubleshooting stored codes.



Parameter Number:

Parameter Description:

Valid Values:
(Note: A minus sign on the display range means to add 100 to the value displayed, -155 is 255.)





1


Temp Setting


60F to 90F

2


In-Car Temp Sensor


10 = HOT -130 = 230 = COLD

3


Outside Temp Sensor


10 = HOT -130 = 230 = COLD

4


Sun Load Sensor


Max light Max Dark

L98/LT1 38 183

LT5 115 -110 = 210

[Notice the solar shield effect!]

5


Ignition System Voltage


0 = 9 Volts -155 = 255 = 16 V

6


Engine Speed (RPM divided by 25)


7


Vehicle Speed


9


A/C System Mode


00 = OFF

01 = Re-Circulation

02 = A/C

03 = Bi-Level

04 = Heater

06 = Defrost

07 = Vent

10 = Manual Re-Circulation

10


Blower PWM


0 = 0 Volts 128 = 14 Volts

11


Program Number


00 = COLD -155 = 255 = HOT

12


Mix Number


-155 = 255 = COLD 00 = COLD

16


Coolant Temperature In degrees C


17


Solar Correction


114 = Max light 128 = max dark

30


Stored Full Hot Value


0 to 50

31


Temp Door Travel Range


100 to 200

34


Temp Door Position Requested


00 = Full HOT -153 = 253 = Full COLD

35


Compressor On Time


.1 second increments

36


Number Of Times Below Critical Time


37


Software Version Number

 

[92BlackVette]

I want to say I had codes stored last night, and during troubleshooting, I pulled the fuse which cleared the codes, now I have to wait to see if they come back. I was able to get the system to blow cold air this morning for about a minute then it went warm again:W

I will run through 1C1-3 and see if I could get the error to come back.

 

[Schrade]

So here is where I am at:
I have checked for a blown A/C - Gauge fuse
Loose/disconnected AC wire connector
Checked blower for fan operation
Engine cooling fan operation
Compressor isn't seized
*********
Next Steps--->I am working on checking on the clutch operation, and codes 66,67,68,69


Concerning issues:
My Mickey Mouse gauge says there is 150 LBs of pressure on the low side! On or Off

My range on the low side should be between: 29 to 42 PSIG, WTF!

Low side pressure that reads THAT high is okay if the motor is NOT on. If the motor is ON, AND the AC is 'ON' (high), then the compressor is not moving the refrigerant. The pressure should have dropped significantly.

High static pressure like you are showing leads me to believe you have plenty of coolant, and that your low pressure sensor switch has failed. Do you know how to jump it?

edit:
Since you got cold air this am, you probably do NOT have a bad switch. Possibly a clogged orifice tube stopping flow. Cheap, but the refrigerant must be discharged, new filter, then recharged.

 

[92BlackVette]

The FSM calls for these clogs to have "freeze" spots in certain parts near the clog. I checked for such spots and haven't seen anything thus far. I am going to run the AC in the next hour for about 30 minutes and I am sure I will get that code back!

 

[G Winter]

A plugged orifice tube would cause the high side to read very high. Possibly as high as 400 psi.
The static low side pressure can vary a great deal with diff temps.
From what you have said I say the compressor isn't engaging.

Glenn

 

[92BlackVette]

Well it has been running great yesterday afternoon, and this morning. I am having trouble recreating the problem at this time now!

 

[G Winter]

I am not sure about the corvettes but on some GM systems
if it is run with low pressure you have to remove power from
the system to reset it or the compressor will not run.

Glenn

 

[Curious George]

I notice you have a '92. That means you "had / have" R-12 (Freon) unless it was converted. When the recharge was done, did they put R-12 back in or R-134? If they put R-134 in you may have some real issues brewing if the conversion was not done correctly.

CG

Do we even know what we are working with? 92blackvette never answered my question above.

Another alternative maybe that the system is over-charged. This happened on my '87 Camaro. I took a few onces (of refrigerant) out and it started working perfectly.

CG

 

[92BlackVette]

Yes, it was converted to R134-A, ester oil changed, whole nine yards.

So guess what! Its back!

Here is the read out at idle:
00 - 09
01 - 64
02 - 134
03 - 87
04 - 197
05 - 107
06 - 27
07 - 00
09 - 02
10 - 48
11 - 00
12 - -155
16 - 86
17 - 128
19 - 103
20 - 128
21 - 145
Ran out of space on my paper......

According to 1C1-20:
The next step is to full the fuse, clear the codes again, add 1 LB of R134a, check for leaks (I don't see oil so I will have to use that trusty black light)

Then depending on that, check for clutch cycles......

 

[rkew]

So where did you end up on this one? My '91 has been doing the same thing for years. I had it converted to R134 years ago by a GM dealer while trying to get the issue fixed but no luck - and then I moved out of state so I couldn't continue the process with that dealer. It's a Sunday-driver so no AC isn't a huge deal but it would certainly be nice to have back.

After resetting everything by disconnecting the battery, mine will blow cold air for a minute or so, the engine will sometimes almost stall, and then no more AC and a blinking light. I'll have to try the codes thing mentioned above and see what I get.

 

[Curious George]

So where did you end up on this one? My '91 has been doing the same thing for years. I had it converted to R134 years ago by a GM dealer while trying to get the issue fixed but no luck - and then I moved out of state so I couldn't continue the process with that dealer. It's a Sunday-driver so no AC isn't a huge deal but it would certainly be nice to have back.

After resetting everything by disconnecting the battery, mine will blow cold air for a minute or so, the engine will sometimes almost stall, and then no more AC and a blinking light. I'll have to try the codes thing mentioned above and see what I get.

If you do not have a set of A/C gauges I would at least invest in a decent set. Like any good tool, they will pay for themselves in time.

Trying to diagnose an A/C problem without gauges is frustrating at best. In your reply above, you say that "sometimes the engine will almost stall", this may indicate a problem with the compressor / clutch assembly.

CG