Here's a comment about another means of controlling an electric fan.
As I think is well known, my 1998 Suburban and I suspect all 1996 and later, the high-pressure switch (~450 PSI, from memory) near the high-side service port has two functions AFAIK when activated (both described in the GM service manual):
- the ECU forces the system into recirc mode, and
- If equipped with the aux cooling fan on the condenser / radiator, the ECU turns the fan on.
These operations can be demonstrated by removing the switch's connector and shorting the terminals with a jumper.
By replacing that high-pressure switch with one which operates at a lower pressure (e.g., 180-220 PSI), the aux cooling fan can effectively be turned on when the AC compressor engages. This isn't a bad option if one doesn't object to the forced engaging of recirc which would also occur.
Methods for enabling ECU control of an aux fan, if not already present on the vehicle, are known.
Others might have better ideas, as well. I like what you've done but I would like to avoid the plumbing changes.
As I think is well known, my 1998 Suburban and I suspect all 1996 and later, the high-pressure switch (~450 PSI, from memory) near the high-side service port has two functions AFAIK when activated (both described in the GM service manual):
- the ECU forces the system into recirc mode, and
- If equipped with the aux cooling fan on the condenser / radiator, the ECU turns the fan on.
These operations can be demonstrated by removing the switch's connector and shorting the terminals with a jumper.
By replacing that high-pressure switch with one which operates at a lower pressure (e.g., 180-220 PSI), the aux cooling fan can effectively be turned on when the AC compressor engages. This isn't a bad option if one doesn't object to the forced engaging of recirc which would also occur.
Methods for enabling ECU control of an aux fan, if not already present on the vehicle, are known.
Others might have better ideas, as well. I like what you've done but I would like to avoid the plumbing changes.
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