The A/C Amp Thread (1 Viewer)

[Pinittowinit]

So if I'm reading this correctly... If I have a holley carb on my truck if I remove or cut the resistor shown the AC compressor will kick on at any rpm.

 

[TrickyT]

So if I'm reading this correctly... If I have a holley carb on my truck if I remove or cut the resistor shown the AC compressor will kick on at any rpm.

Correct, including 0 rpm. So if you want to help your starter motor out you should manually switch off the A/C before cranking.

 

[Pinittowinit]

Nice thank you.

 

[87CRUSR]

Great info TrickyT

 

[Pinittowinit]

Mine looks like neither. 1982

 

[Spike Strip]

@Rigger or @Mace --- This REALLY needs to be in the FAQ !!!!!!!!!!! (and there's a couple other threads that should be linked with it...)

(link)

 

[TrickyT]

Mine looks like neither. 1982View attachment 1112774

Yours looks the same as the 1985-and-later FJ60 amp, but with some components (4 resistors and a capacitor) missing in the top-left corner. I can tell it's basically the same as the lower photo in post #2 because the IC is the same (p/n SE012) and the relay and potentiometers look the same. I don't have an FJ60 amp in my possession any longer and so can't easily say what part of the overall circuit the missing components affect, but I'm pretty sure it is not the RPM sensing circuitry. I do remember from talking to @beno that pre-1985 LC's use a different thermistor part number so the change may be related to that.

 

[Rigger]

@Rigger or @Mace --- This REALLY needs to be in the FAQ !!!!!!!!!!! (and there's a couple other threads that should be linked with it...)

(link)

I'll get it in there tomorrow. Thanks!

 

[Rigger]

OK - I got this one in the FAQ

 

[Spike Strip]

Aye, Captain! Full speed ahead!

 

[Spike Strip]

Yeah, baby - I've been looking for this thread for two hours, then I remembered, 'It's in the FAQ!'

 

[Spike Strip]

Truck sat for a few months and I used it yesterday and the A/C was warm. I adjusted the Amp so it cycles the compressor as much as possible, but still warm (or slightly cool). Compressor and most other components are < 5 years old.

I have R134a, what should the stuff in the sight glass look like? Mine is kinda milky white...

 

[MANUCHAO]

Should be green.. Me thinks..

 

[FJ60Cam]

I think you can only use the sight glass to check the charge with R-12. I don't think it will clear up with the 134. I'll check mine and compare.

If you have (the red knob?) adjusted to where the compressor cycles more frequently, you are raising the coil temperature setpoint upward. Adjust it the other direction, for less cycling, and see if that helps. You probably aren't humid enough in the '818 to freeze up the coil unless it runs for hours on end.

 

[Spike Strip]

Humid, but prolly not as bad as Memphis can get... I think I just have to take it to a pro and let 'em have a look. A/C is just one of those thing I don't really have to know, I guess

 

[doug720]

I bet you are low on 134?

If you are using a R12 compressor with 134, leak downs are common. 134 molecules are much smaller than R12's. Many modern 134 compressors have triple lip seals to help keep the gas in. Same thing happens with o-rings.

If you don't have gauges and adapters, many AC shops will check charge and give a top off fairly cheap.

Just an idea.

 

[Spike Strip]

Good info, Doug; I didn't know any of that. Will try a recharge first. Thanks.

 

[Alaska Ranger]

Can you suggest why the '88 62 I've just purchased - and its A/C works extremely well - has the ground(?? - top leftmost spade on the circuit board) disconnected? Was the PO trying to provide A/C at all times?

 

[TrickyT]

Can you suggest why the '88 62 I've just purchased - and its A/C works extremely well - has the ground(?? - top leftmost spade on the circuit board) disconnected? Was the PO trying to provide A/C at all times?

Well it should first be noted that the spade terminal is not a ground! (See circuit diagram in post #3.) The spade terminal goes to the ignition start circuit in order to disengage the A/C when trying to start the engine.

 

[Alaska Ranger]

Right. And already I had noticed that it was better to make sure the a/c was off when trying to start, so obviously that is the sort of issue this entire circuit board is created to address. But I wonder if there could be a good...or bad...reason the PO disconnected it. Any clues, anyone?