Dead Battery, now No AC
05-24-2020, 11:40 AM
#1
Intermediate
Thread Starter
Dead Battery, now No AC
After battery discharge, not much driving during past months, battery was not completely dead. I disconnect ground and put charger on. Once charged, car starts, everything operates except AC.
05-24-2020, 02:31 PM
#5
Same symptoms for me, will have it checked ln tuesday.
Last edited by Railmaster.; 05-24-2020 at 05:13 PM.
05-24-2020, 02:50 PM
#6
Instructor
Pretty simple diagnostic. First check voltage at the compressor, if no voltage check the compressor relay in the engine compartment. If the relay checks out, check the fog light relay in the front trunk fuse box. Beyond that check the coolant pressures and then lastly the 3 way pressure switch. My money is on the compressor relay or the fog light relay.
05-25-2020, 10:46 AM
#7
Intermediate
Thread Starter
Thanks for the tips, AC relay tested OK, there is no 12 volts at compressor. Condenser fan runs, checked 7.5 volt fuse near ac relay, and 25 amp fuse in front fuse box.do you think a coincidence AC stops after dead battery? I had a dead battery about a year ago, recharged and AC worked fine after that. I know you have to drive the car after you recharge to get electronics back in order. Is there another fuse by chance? Thanks
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05-25-2020, 05:51 PM
#9
RL Community Team
Rennlist Member
Rennlist Member
Don't look too deeply until you have verified the refrigerant fill.
I would go to Wal-Mart and buy two $7 cans of refrigerant and the reusable filling hose. Hook it up to the low-pressure side of the compressor and run it in with the can upside down, the engine running and the AC set to max. If the refrigerant is low it will empty into the system and, I would think, cause the compressor to start running. If not your problem lies somewhere else. Once the one can is in and the compressor is running check the vent temperatures if they are nice and cool you are done. If not, put the 2nd can in. I do this little dance in the Wal-Mart parking lot every 4 to 6 years. I also every once in a while use the refrigerant that has the system lubricant mixed in. HVAC guys will throw up over this low tech recommendation but it seems to work for me over many years and two 911.
Andy
The 993 has a Three-level pressure switch
The switch really contains two switches. One of them cuts the CCU clutch signal and turns off the compressor if the pressure is too low, (2.5 bar) or too high (27 bar) in the A/C refrigerant circuit system. The other switch set the condenser cooling fan speed to high if the pressure exceeds 17.5 bar. The sensor assembly is mounted on the metal A/C pipe near the HVAC servo motors in the trunk.I would go to Wal-Mart and buy two $7 cans of refrigerant and the reusable filling hose. Hook it up to the low-pressure side of the compressor and run it in with the can upside down, the engine running and the AC set to max. If the refrigerant is low it will empty into the system and, I would think, cause the compressor to start running. If not your problem lies somewhere else. Once the one can is in and the compressor is running check the vent temperatures if they are nice and cool you are done. If not, put the 2nd can in. I do this little dance in the Wal-Mart parking lot every 4 to 6 years. I also every once in a while use the refrigerant that has the system lubricant mixed in. HVAC guys will throw up over this low tech recommendation but it seems to work for me over many years and two 911.
Andy
05-25-2020, 06:09 PM
#10
Don't look too deeply until you have verified the refrigerant fill.
I would go to Wal-Mart and buy two $7 cans of refrigerant and the reusable filling hose. Hook it up to the low-pressure side of the compressor and run it in with the can upside down, the engine running and the AC set to max. If the refrigerant is low it will empty into the system and, I would think, cause the compressor to start running. If not your problem lies somewhere else. Once the one can is in and the compressor is running check the vent temperatures if they are nice and cool you are done. If not, put the 2nd can in. I do this little dance in the Wal-Mart parking lot every 4 to 6 years. I also every once in a while use the refrigerant that has the system lubricant mixed in. HVAC guys will throw up over this low tech recommendation but it seems to work for me over many years and two 911.
Andy
The 993 has a Three-level pressure switch
The switch really contains two switches. One of them cuts the CCU clutch signal and turns off the compressor if the pressure is too low, (2.5 bar) or too high (27 bar) in the A/C refrigerant circuit system. The other switch set the condenser cooling fan speed to high if the pressure exceeds 17.5 bar. The sensor assembly is mounted on the metal A/C pipe near the HVAC servo motors in the trunk.I would go to Wal-Mart and buy two $7 cans of refrigerant and the reusable filling hose. Hook it up to the low-pressure side of the compressor and run it in with the can upside down, the engine running and the AC set to max. If the refrigerant is low it will empty into the system and, I would think, cause the compressor to start running. If not your problem lies somewhere else. Once the one can is in and the compressor is running check the vent temperatures if they are nice and cool you are done. If not, put the 2nd can in. I do this little dance in the Wal-Mart parking lot every 4 to 6 years. I also every once in a while use the refrigerant that has the system lubricant mixed in. HVAC guys will throw up over this low tech recommendation but it seems to work for me over many years and two 911.
Andy
05-25-2020, 07:14 PM
#12
RL Community Team
Rennlist Member
Rennlist Member
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05-25-2020, 10:38 PM
#15