R4 to Sanden whith stock ac lines(for serpantine)

[fortune46x]

As far as wiring goes with the Sanden to the connector on the firewall , do you just plug the single wire into the light green wire on the fire wall ? or the dark green wire on the firewall ?

 

[gmbellew]

you want to tap into the single wire going from the low pressure cutoff switch on the accumulator to the original compressor. I forget if it is light or dark green....but don't bypass the low pressure cutoff switch

 

[c5killer]

This is the info I have been looking for.

@yevgenievich, all I can find are the 8 rib clutches for this model compressor. Did you have to special order a 6 rib?

 

[yevgenievich]

This is the info I have been looking for.

@yevgenievich, all I can find are the 8 rib clutches for this model compressor. Did you have to special order a 6 rib?

Used 8 rib and let it ride on 6. There is a special order 6 available, but a pain to get I believe

 

[c5killer]

Do I need to swap out my high/low switch on the accumulator to one for r134A or just keep the R12 one?

 

[gmbellew]

Do I need to swap out my high/low switch on the accumulator to one for r134A or just keep the R12 one?

existing switch is fine, but you may need to adjust the pressure it cuts off to account for the temp/pressure differences to get better cooling.

 

[yevgenievich]

Either adjust or get one that is set for 134

 

[Backfoot100]

Where exactly is that switch and how do you set it?

 

[R Carnella]

If yours is adjustable then there will be a small flathead screw between the two electrical contacts. It's on the receiver/dryer

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[Backfoot100]

Awesome.
My apologies beforehand for sounding like a rookie. I've been hearing about this switch ever since I did my Sanden conversion but I've always been confused about....
1) Where it is. Thanks for the info.
2) and this is the real question now, would you be increasing or decreasing the switch pressure????

The conversion process from R12 to 134 confuses me. Does higher pressure mean colder air or does lower pressure mean colder air?

 

[Doppleganger]

I've converted probably 25+ older cars from R12 to R134. The pressure switches were always different. ?! They were always mounted on the accumulator.

 

[yevgenievich]

Awesome.
My apologies beforehand for sounding like a rookie. I've been hearing about this switch ever since I did my Sanden conversion but I've always been confused about....
1) Where it is. Thanks for the info.
2) and this is the real question now, would you be increasing or decreasing the switch pressure????

The conversion process from R12 to 134 confuses me. Does higher pressure mean colder air or does lower pressure mean colder air?

Turn the adjustment about 1/8 to 1/4 counter clock wise if I recall correctly. R134 needs to lower pressure couple of psi. Adjustment is best done with gauges and a running system to observe cut off pressure

 

[gmbellew]

adjusting low pressure cutoff switch after R134a conversion

my 1990 suburban was converted to R134a before i purchased it. i have never been happy with the AC performance at idle or in stop and go traffic. it cools well at constant speeds on backroads or on the highway. i plan to add an auxillary cooling fan to help put more air across the condenser at...

www.gmsquarebody.com

 

[R Carnella]

You'll need the ac system running, fully charged and a decently warm day. Connect your gauges and watch low side press. Raise engine rpm to 2500 or so and watch As the low side(really suction side)drop, if low pressure falls below the set cut off point, the switch will open the circuit and turn off the compressor around 35psi.
I turn that little flathead counter clockwise about quarter turn for a lower cut off around 25-28psi.
Keep in mind this is just fine tuning for your ac system, it's not absolutely necessary to mess with this,your ac will work regardless. Much more important to have the correct charge for your system overall. Adjusting this only helps to prevent the compressor cycling on/off to much on cooler days like if you're using defroster on a rainy day and to prevent freezing over in cold climate. On a hot day with system under load your low side pressure should stay around 40/45. Far above the cut off point anyway.

 

[gmbellew]

from the service manual on which way to turn the switch