Looking for some input on our gen I hydraulic fan. The fan itself will not run on high speed with the a/c on. I figured I would test the hydraulic fan actuator so I got a connector from our junkyard and gave the actuator 12v with the car running. Fan came on high so that ruled out the actuator being stuck. My question is do you guys think it would be the high pressure sensor of the a/c system causing the actuator to not allow the fan to run on high speed or is this a DATC issue? A/C cools just fine while the car is moving and has airflow, so I know the compressor is engaging. Will the high pressure sensor allow the compressor to run but not set the hydraulic fan to high speed? Any input would be appreciated. Thanks.
High pressure sensor or DATC?
- Thread starter Bazil
- Start date
joegr
Dedicated LVC Member
The higher speed fan actuation with the AC on is based on the high-side pressure of the AC system. If the high side pressure is not high, the fan will not be requested to speed up, because there is no need.
Your first trouble shooting step is to verify the high side pressure, not to throw parts at it. It's rare for those pressure sensors to fail, and extremely rare (I've never seen it) for one to fail in such a way as to not correctly read the pressure, but to still read enough pressure to allow the clutch to engage at all.
I'll bet that you will find that the pressure is not rising (still less than 100 PSI) when you are at idle. While this could be due to low refrigerant, if you are cooling good at speed, it is more likely due to a bad scroll control valve (not an uncommon failure on these compressors), or due to a bad compressor itself. (Is this an aftermarket compressor?)
You will need a decent dual gauge setup (and know how to use it) to correct diagnose this. If you just dump more refrigerant in and it wasn't low to start with, you could just cause even more expensive problems.
Your first trouble shooting step is to verify the high side pressure, not to throw parts at it. It's rare for those pressure sensors to fail, and extremely rare (I've never seen it) for one to fail in such a way as to not correctly read the pressure, but to still read enough pressure to allow the clutch to engage at all.
I'll bet that you will find that the pressure is not rising (still less than 100 PSI) when you are at idle. While this could be due to low refrigerant, if you are cooling good at speed, it is more likely due to a bad scroll control valve (not an uncommon failure on these compressors), or due to a bad compressor itself. (Is this an aftermarket compressor?)
You will need a decent dual gauge setup (and know how to use it) to correct diagnose this. If you just dump more refrigerant in and it wasn't low to start with, you could just cause even more expensive problems.
Thanks Joe,
The compressor is the original compressor to the car, the a/c system itself has never been touched. We don’t have a dual gauge setup currently but will get one, as it’s been on my list of things to get for the garage. Car isn’t really driven all that much and just stays in the garage but the a/c issue is something we’d like to remedy for when the car is taken to shows etc. ( hopefully we’ll be able to take it to a show soon). Thanks again!
The compressor is the original compressor to the car, the a/c system itself has never been touched. We don’t have a dual gauge setup currently but will get one, as it’s been on my list of things to get for the garage. Car isn’t really driven all that much and just stays in the garage but the a/c issue is something we’d like to remedy for when the car is taken to shows etc. ( hopefully we’ll be able to take it to a show soon). Thanks again!