AC Problems - 1991 C4
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Joined: Jul 2014
Posts: 50
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From: Portsmouth VA
First I set the AC on max cool (recirculate) then set it at 60 the lowest temp. The FSM might even say to press the lower the temp button after you set to 60 but I can't remember for sure. Once I did that I puled the fuses to reset and then immediately started the recharge after restarting the engine. The compressor continued to cycle as I added 134 until it ran 100% of the time once I had enough 134 in the system. I am traveling but if I can figure a way to copy and paste the info from the FSM I will send you a PM.
Melting Slicks
Joined: Aug 1999
Posts: 2,240
Likes: 42
From: Baltimore, MD USA
Well, the weather warmed up an the AC is not working. My 91 Vette has the automatic climate control system. Here’s what I know and I have done:
- Off button was flashing indicating and error
- Held the air up & down buttons to get to code screen
- Hit the center button and got an error code of 09 - low refrigerant
- System had about 40lbs should have been enough, but pushed it up to 50lb @ ambient outside temperature of 85 degrees
- Reset the system as per owners manual by pulling courtesy light and radio fuses
- The compressor attempted to engage; after a couple of click it stopped
- Checked get 09 error code
- Pushed it to 55lbs and reset.
- Nothing and still get 09 error code
- Swapped gauges to make sure I was getting an accurate reading - gauge readings were identical
- Checked 2 connections at the compressor, I have a good ground and 0 voltage coming to the compressor.
- All fuses are good
Any additional suggestions would be great appreciated. I’m sure I’m missing something simple. Thanks!!
- Off button was flashing indicating and error
- Held the air up & down buttons to get to code screen
- Hit the center button and got an error code of 09 - low refrigerant
- System had about 40lbs should have been enough, but pushed it up to 50lb @ ambient outside temperature of 85 degrees
- Reset the system as per owners manual by pulling courtesy light and radio fuses
- The compressor attempted to engage; after a couple of click it stopped
- Checked get 09 error code
- Pushed it to 55lbs and reset.
- Nothing and still get 09 error code
- Swapped gauges to make sure I was getting an accurate reading - gauge readings were identical
- Checked 2 connections at the compressor, I have a good ground and 0 voltage coming to the compressor.
- All fuses are good
Any additional suggestions would be great appreciated. I’m sure I’m missing something simple. Thanks!!
Something is wrong if the can is heating up.
After you attach a new refrigerant can to the accumulator fitting you need to loosen the hose end at the accumulator to purge any air out of the charging hose.
At ambient temperature with the system not running the static pressure on both the low and high side at ambient 80F the pressures should be close to 85 psi, at 85 F around 95 psi, at 90F 105 psi. If the static pressures are lower than at that particular temperature you're low on refrigerant assuming a vacuum has been pulled on the system. These are static pressures.
To keep the compressor on while charging, you clear the codes.
At the evaporator top pipe you unplug the connector and jump the two female pins on the connector plug. This will keep the compressor clutch engaged.
You really need a gauge to monitor the high pressure side.
Start the engine and the compressor should draw in the refrigerant.
Once you get enough refrigerant in, remove the jumper and reconnect the plug. They system will now cycle on it's own.
Below is a charging pressure chart for R134a.
Last edited by Hooked on Vettes; Jun 11, 2015 at 10:22 PM.
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Joined: Jun 2006
Posts: 364
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From: Monroe Washington
I'm guessing all of the refrigerant leaked out and what you are seeing is compressed air and the R134a you added in the system. In that case you would need to pull a vacuum and see if it holds.
Something is wrong if the can is heating up.
After you attach a new refrigerant can to the accumulator fitting you need to loosen the hose end at the accumulator to purge any air out of the charging hose.
At ambient temperature with the system not running the static pressure on both the low and high side at ambient 80F the pressures should be close to 85 psi, at 85 F around 95 psi, at 90F 105 psi. If the static pressures are lower than at that particular temperature you're low on refrigerant assuming a vacuum has been pulled on the system. These are static pressures.
To keep the compressor on while charging, you clear the codes.
At the evaporator top pipe you unplug the connector and jump the two female pins on the connector plug. This will keep the compressor clutch engaged.
You really need a gauge to monitor the high pressure side.
Start the engine and the compressor should draw in the refrigerant.
Once you get enough refrigerant in, remove the jumper and reconnect the plug. They system will now cycle on it's own.
Below is a charging pressure chart for R134a.
Something is wrong if the can is heating up.
After you attach a new refrigerant can to the accumulator fitting you need to loosen the hose end at the accumulator to purge any air out of the charging hose.
At ambient temperature with the system not running the static pressure on both the low and high side at ambient 80F the pressures should be close to 85 psi, at 85 F around 95 psi, at 90F 105 psi. If the static pressures are lower than at that particular temperature you're low on refrigerant assuming a vacuum has been pulled on the system. These are static pressures.
To keep the compressor on while charging, you clear the codes.
At the evaporator top pipe you unplug the connector and jump the two female pins on the connector plug. This will keep the compressor clutch engaged.
You really need a gauge to monitor the high pressure side.
Start the engine and the compressor should draw in the refrigerant.
Once you get enough refrigerant in, remove the jumper and reconnect the plug. They system will now cycle on it's own.
Below is a charging pressure chart for R134a.
By clearing the codes and starting, the compressor clutch will cycle 9 times then stops, generating a "9" error code.
