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AC parts

Jaryd

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I hope it don’t turn into that down here. Ive been going to Johnstone for the past 17 years because they are the best to do business with out of all the commercial/ Industrial HVAC houses around here. Cheaper for the same material to.
 

MrMarty51

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I hope it don’t turn into that down here. Ive been going to Johnstone for the past 17 years because they are the best to do business with out of all the commercial/ Industrial HVAC houses around here. Cheaper for the same material to.
I have bought from Johnstone before. Online. Thermocouplers and them little millivolt generator thingamabobs for the gas log fireplace.
 

Twisted Steel Performance

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Well I haven't installed any new parts yet, it's just too hot for me to deal with pulling the dash, I did however put new seals on the rear of the compressor, pulled a vac and charged it...
It's blowing cold but the compressor never cycles and the fan has a trinary switch and the fan never stops being locked..
My gauges won't hook up to the high side so I don't know what the pressures is, @ 93* the low is only 37..

I'm going to take it to my buddy's shop and pay him to replace the evaporator, I'll do everything else.. he says he doesn't ever look at the gauges, just puts in the amount his book says it holds, says the pressures with 134 you can't go by the pressures.... I may need to find another ac shop but he is one of the only around...

On Trinary switches, it's in the high pressure line behind the compressor, I don't know anything about it other than it's a 2 wire... what pressure trinary switch should I get in case this one is bad...
 

WarWagon

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Same thing as Enviro-Safe, ES, refrigerants = flammable propane and butane. Link below and I recommend ES over this outfit as I used ES before.

The Industrial mix isn't compatible with the low pressure cycling switch as it's below freezing when the switch cycles. It will ice up the evap on anything less than high. Put a probe on the evaporator like Dodge does and it's colder than R12. Anyone remember blowing snow out the vents with a A6 and R12? Yeah, unlike cool R134a, this stuff has that Cold Bite to it.

When it's 115F+ out and dry... this stuff is dripping water out the evaporator drain. R134a systems aren't capable of that here.

Their, ES, regular replacement works very well in these GM systems with the normal low pressure switch esp. with a VOV.

 

Twisted Steel Performance

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WarWagon

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Regular with dye. Use R134a pressure switch.

Regular ES on left and the industrial on the right. Note the pressure around 32F where industrial is way higher. It's ~20F when the R134a pressure switch opens. Charts are half-assed only going up to 133 degrees... Need to go up to 200F and 500 PSI where systems explode from pressure. Note the lower head pressures on the high side at 133F.

HC_compair.jpg
 
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WarWagon

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Only the OEM GM Refrigerant 134a switch I know of. Never found one for the ES industrial version: so for simplicity sake I suggest the regular stuff.

I pull a vac on the system. Not sure what moron came up with not doing that.

Otherwise a VOV and R134a is the safest way to go as it isn't flammable like the propane and butane these refrigerants are.
 

Twisted Steel Performance

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@WarWagon , one last thing, as you know the 93 evaporator had the tube in the lower small line, a newer condenser is made for the tube to go in it... will it make any difference if the tube is in the evap vs the condenser ? I do have 2 different vov tubes for either location...
 

WarWagon

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The bottom of the evap eliminates that long "cold" line in the hot engine compartment. IMO it was only moved to the condenser for noise. However it could change the charge level in the system from the volume of that line as it's figured as liquid.

I ran the OT in the evaporator on my 1992 project. Long story tracking down a bad VOV at the time and wound up with that connection open so there the OT went in.
 

FellowTraveler

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Only the OEM GM Refrigerant 134a switch I know of. Never found one for the ES industrial version: so for simplicity sake I suggest the regular stuff.

I pull a vac on the system. Not sure what moron came up with not doing that.

Otherwise a VOV and R134a is the safest way to go as it isn't flammable like the propane and butane these refrigerants are.
If I remember right, ES does not produce acid if moisture is in the mix. This is why, the mention of not having to pull vac on the system, I always pull down and deep on vacuum too.
 

THEFERMANATOR

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You can use your stock R12 low pressure switch with the HC based refrigerants. Most R134 low pressure switches cycle off around 22 psi, if you look at that chart, 22 psi of r134 is equal to 26 for ES, and R12 low pressure switches happen to cycle off around 25-28 psi. It is best though with ES and a flooded evac to not use a low pressure switch, but instead switch to a thermal cycling switch where it has a temp probe in the evaporator core and uses a temp switch to cycle the system by actual evap temp instead of low pressure.

And your AC guy cannot charge a r12 to R134 retrofit by weight. There is no set rule of percentage of r134 vs r12 to charge by. And when installing aftermarket components, many times you have to adjust the charge amount even in newer cars because the replacement parts are not exactly like the oem parts were. This is why I always charge by temp whenever possible.
 

Twisted Steel Performance

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You can use your stock R12 low pressure switch with the HC based refrigerants. Most R134 low pressure switches cycle off around 22 psi, if you look at that chart, 22 psi of r134 is equal to 26 for ES, and R12 low pressure switches happen to cycle off around 25-28 psi. It is best though with ES and a flooded evac to not use a low pressure switch, but instead switch to a thermal cycling switch where it has a temp probe in the evaporator core and uses a temp switch to cycle the system by actual evap temp instead of low pressure.

And your AC guy cannot charge a r12 to R134 retrofit by weight. There is no set rule of percentage of r134 vs r12 to charge by. And when installing aftermarket components, many times you have to adjust the charge amount even in newer cars because the replacement parts are not exactly like the oem parts were. This is why I always charge by temp whenever possible.
@THEFERMANATOR , do you know of a thermal switch that will go where the low pressure switch is in the dryer , is that where you are suggesting using one?
 

THEFERMANATOR

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@THEFERMANATOR , do you know of a thermal switch that will go where the low pressure switch is in the dryer , is that where you are suggesting using one?
The thermal switch must be installed into the actual evap core, it cannot go into the line. The problem you run into wth the HC based refrigerants is they do not actually fully flood the evap. When charged fully they will still boil off some in the evap due to GM's flooded evap design. So you cannot fully go by low pressure. The 2nd best option would be to use an early style low pressure switch you can manually adjust it to cycle off at the higher pressure.
 

Twisted Steel Performance

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Thanks, I'm looking for a r12 switch now, and I have read most gm switches are adjustable, I have a new purple switch here I just need to look at it and see if there is a screw between the connection prongs...
 
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