LM7 stalling issues with air conditioning
07-13-2012, 12:33 PM
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LM7 stalling issues with air conditioning I swapped a LM7 5.3L into a 1993 stepside truck with a LS1 hot cam and I have finally managed to get the original TBI AC compressor to run on the 5.3L without tossing or shredding the belt.
My issue is when the motor is warm, the blasted thing will stall right after startup when AC is engaged. Used to be real bad during early bracket testing but I changed the crank pulley to a 27% underdrive which helped put less AC shock on the motor. If I have the throttle stop screw turned where I can fire the truck up and it not stall, I have a high idle after about 3 minutes of run time and a REALLY high idle of the AC isn't running. But if I set the throttle stop for a good idle speed I have a slim to no chance of that engine running with the AC engaged at least not for the first couple minutes of run time and its worse if firing up the engine when its hot. The colder the motor the more likely it will stay running with the AC engaged.
I doubt I am the only one that has had this problem. Since this is a swap, I have no way to tell the PCM that the AC compressor is engaged for it to compensate quicker on its own like going from park to drive on the transmission.
My issue is when the motor is warm, the blasted thing will stall right after startup when AC is engaged. Used to be real bad during early bracket testing but I changed the crank pulley to a 27% underdrive which helped put less AC shock on the motor. If I have the throttle stop screw turned where I can fire the truck up and it not stall, I have a high idle after about 3 minutes of run time and a REALLY high idle of the AC isn't running. But if I set the throttle stop for a good idle speed I have a slim to no chance of that engine running with the AC engaged at least not for the first couple minutes of run time and its worse if firing up the engine when its hot. The colder the motor the more likely it will stay running with the AC engaged.
I doubt I am the only one that has had this problem. Since this is a swap, I have no way to tell the PCM that the AC compressor is engaged for it to compensate quicker on its own like going from park to drive on the transmission.
