A/C clutch not engaging automatically
06-26-2021, 03:38 PM
#1
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A/C clutch not engaging automatically
I've scoured this forum, 996 and 997 forums plus many others trying to determine the root cause of no A/C. This started last spring and I have attempted troubleshooting this problem on and off for the past year. Presently, I have a switched wire circuit from the fuse panel directly to the compressor clutch so that I can manually turn on the A/C (and this works)!
Symptom:
No A/C (although the A/C button on the console lights up when I push it to "off") , however, there is also no engine compartment fan, and on start-up (about a 30 second delay), the front cooling fans turn on to High. The internet notes that this is a normal safeguard if the engine is running hot!
I have a Durametric Pro so I can turn on/off each of those components, including 3 speeds for the cooling fans, however it wont communicate with the can-bus high and low.
Forum search results:
Bad "A/C pressure switch"....vacuumed out the A/C refrigerant, replaced the switch and recharged the system. NO CHANGE.
Bad "HVAC Blower Motor Resistor Regulator A/C"...took the passenger side dash apart, replaced the resistor. NO CHANGE
Bad "A/C relay" at driver side rear tail light...got a new one (although the original worked when voltage was applied). NO CHANGE
Removed the HVAC module behind the center console, cleaned all of the connections and reinstalled. NO CHANGE
I must also note that last Feb, I had Softronics flash my DME to a 997 since I replaced the 3.4 with a 3.6 with GT3 throttle body, IPD intake plenum and Soul exhaust. I suspected that the flash was causing this since the A/C worked the previous summer, but not the summer after...coincidence? Scott at Softronic has been helpful and states that the flash could not just drop some lines of code and the rest of the car still work.
So...I am at a loss! Anyone else run into this situation?
Symptom:
No A/C (although the A/C button on the console lights up when I push it to "off") , however, there is also no engine compartment fan, and on start-up (about a 30 second delay), the front cooling fans turn on to High. The internet notes that this is a normal safeguard if the engine is running hot!
I have a Durametric Pro so I can turn on/off each of those components, including 3 speeds for the cooling fans, however it wont communicate with the can-bus high and low.
Forum search results:
Bad "A/C pressure switch"....vacuumed out the A/C refrigerant, replaced the switch and recharged the system. NO CHANGE.
Bad "HVAC Blower Motor Resistor Regulator A/C"...took the passenger side dash apart, replaced the resistor. NO CHANGE
Bad "A/C relay" at driver side rear tail light...got a new one (although the original worked when voltage was applied). NO CHANGE
Removed the HVAC module behind the center console, cleaned all of the connections and reinstalled. NO CHANGE
I must also note that last Feb, I had Softronics flash my DME to a 997 since I replaced the 3.4 with a 3.6 with GT3 throttle body, IPD intake plenum and Soul exhaust. I suspected that the flash was causing this since the A/C worked the previous summer, but not the summer after...coincidence? Scott at Softronic has been helpful and states that the flash could not just drop some lines of code and the rest of the car still work.
So...I am at a loss! Anyone else run into this situation?
07-01-2021, 02:48 PM
#3
I honestly have no idea but if it's not too difficult are you able to revert to the 987 firmware just to make sure it's not something in the 997 firmware that slightly different?
07-01-2021, 05:59 PM
#4
the consequences of software bugs are completely unpredictable. ask any professional programmer and they'll also tell that there's no such thing as a program as complicated as emu software that is bug free or can even be tested in such a way as to result in a bug free program.