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1997 P38 4.6 HSE
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So this '97 P38 is new to me and I am new to it. I couldn't figure out why the "AC Off" button didn't seem to turn the AC off, but I think I see why now. The AC condenser is hot-wired to 12v, which actually runs through the firewall and into my stereo compartment! I discovered this when topping off my refrigerant due to mediocre cooling during very hot days... which is still a mystery after top-off. I'm guessing there is a malfunction or error in HEVAC, which is why the condenser is hot-wired, staying true to the "repair" style I see elsewhere in the vehicle.

What do you all think? Both about the hot-wire and about the mediocre performance on hot (90F/32C) days. It was mentioned that I should take a look at the AC clutch gap.

I DO have book icon and both blowers are working.
 

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Probably a work around to get round a dodgy connection between HEVAC and compressor (condenser is the radiator like thing at the front). The compressor clutch feed comes from the HEVAC, goes via the multiway connector behind the RH kickpanel, through the low pressure switch before arriving at the compressor. The connector behind the RH kickpanel is well known for going green and hairy and the pressure switch plug has also been known to go high resistance too. Disconnect the hotwire and see if there is any voltage getting to the compressor. You may find a very low voltage arriving at the compressor (around 8V is common).

As for the mediocre performance, it needs gassing properly. Any existing gas recovered, the system pressure tested with Oxygen Free Nitrogen at 10 bar for 30 minutes, system vacuumed out and refilled with 1250 grams of R134a. Just dumping an aerosol of carp in there isn't the way to do it.
 
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I think there's a sensor to recognize a low refrigerant charge, which prevents the compressor to engage if it's tripped. I think the bypass is there to go around this sensor. As for mediocre performance, most likely the blend motor is stuck partially, preventing cold air to flow into the cabin.
 
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