73 ac rebuild, need guidance
 

I’m gathering parts and want to make sure I’m on the right track.

Background:
73 blazer basically I have no ac parts except the ductwork and Evap housing.

New parts ordered:
Evap
Accumulator
Line set
Pro6ten compressor
Binary hi/lo switch
134 blue orifice tube and adapter (to run in the larger Evap pipe from the early trucks)
Parallel flow condenser


The original schematic shows to engage the compressor clutch it has to be satisfied by low pressure switch and then in series by the thermal switch to pass current to the clutch coil.


So my main question is will I still wire my thermal coupling compressor cut out switch in series with the compressor clutch, or just use the hi/low binary switch for compressor cycling

Thanks

Re: 73 ac rebuild, need guidance
 

The binary switch is a combination LPCO HPCO switch
Put the binary switch in the high side plumbing off the compressor and keep the original LPCO on the accumulator/dryer.

Run the thermal cutout switch in series with the other two.

I usually dump all the oil out of the new compressor and fill it with the same amount of fresh ester or PAG oil with UV dye and inject the rest of the oil charge once the system is vacuumed down.

I'm interested to read how well that A6 replacement works.

Re: 73 ac rebuild, need guidance
 

Awesome,thanks!

Just to verify..... the thermal switch I’m referencing is the one that mount on the hvac box and probs into the Evap coil to monitor freeze up....not a superheat thermal cut out

Are we talking about the same switch?

Reid

Re: 73 ac rebuild, need guidance
 

Yes. That thermal switch is there to cycle the compressor to keep the evaporator from icing up.
A fully charged system shouldn't have trouble with evaporator icing but early automotive AC systems leaked.

Re: 73 ac rebuild, need guidance
 

Thanks!

I was confused for a little bit on the difference between a modern cycling switch and the binary switch.

Also I was confused about the low side of the binary switch ever doing anything since it was in the liquid line....but since talked to someone about it being more like a absolute low switch (basically completely out of refrigerant) to ever trip the low side.

I think I understand what’s going on now.....thanks again