R-12 to R-134 conversion - Page 3 - ZR-1 Net Registry Forums

-=Jeff=- · 07-20-2020

What do the fittings look like for the high side and low side, that will help to determine R-12 or R134a

Ccmano · 07-20-2020

Quote:

Originally Posted by -=Jeff=-

What do the fittings look like for the high side and low side, that will help to determine R-12 or R134a

The fittings are R12. But that doesn't mean someone didn't use adapters and R134a a few years ago when the compressor was done. Especially since it was in CA at the time where R12 is a big no-no.

Also trying do determine if I need a white or a black orifice tube.
H

-=Jeff=- · 07-20-2020

Gotcha as for the orifice tube. Which are listed for the car?

XfireZ51 · 07-20-2020

All I did was replace O-rings, new PAG oil in compressor and different fitting for evaporator/dryer.

Ccmano · 07-20-2020

Quote:

Originally Posted by -=Jeff=-

Gotcha as for the orifice tube. Which are listed for the car?

The white tube is standard. It appears the black tube is an optional automatic adjusting tube for severe climates. Anybody ever use one?
H

PhillipsLT5 · 07-20-2020

Years ago I installed a severe climate tube in Hot PHX with R 12 worked fine, blew 38-40 degree air out, dont know about the color

Matt B · 03-31-2021

As mentioned in another threat I my R-12 was drained during import into Europe. So now I need to switch to 134a as R-12 is illegal here...
However, reading through this threat left some confusion. Appreciate if someone can add some clarity on the following:

- switches: it was said that R-12 high pressure switch will not operate correctly but can be adjusted by turning the adjustment screw 1/4 ccw. So no other switches or adjustments other than that needed, correct?

- PAG oil: I'm an A/C dummy so sorry for that stupid question (I know there are no stupid questions but I think this one is...) but the oil is not only inside the compressor but the entire system, right? So, I need to remove the compressor from the car, drain it and also flush the rest of the system?
However, in an case I can re-use the OEM compressor with no further modifications?

- Orifice tube: do I need to swap it? If so, Rockauto lists a variety:
*GM GENUINE 155151 {#03033879, 3033879, 3033879OEM}
*ACDELCO 155754 {#19189768, 88919511} - "OE replacement"
*ACDELCO 1550120 {#19189841, 89032868} - "Optional Automatic Adjusting Orifice Tube For Normal Climates Under 105 Degrees"
*ACDELCO 1550122 {#19189843, 89032872} - "Optional Automatic Adjusting Orifice Tube For Severe Climates over 105 Degrees"
Which one is correct? Germany is not a super hot place, however does the "hot climate version" maybe improve the cooling power? I heard that the ZR has it's limitations here...
Will I need a remover tool to get the job done or will needle nose pliers work?

I already have a new dryer on the shelf which I will install including some fresh O-Rings. Now I need to collect the rest and plan the actual work.

Sorry for all these questions but as spare parts are sometimes hard to come by over here I became very careful to not destroy things due to stupid mistakes

Subfixer · 03-31-2021

I converted my 92, but it was not easy.
R12 switches and hoses are SAE threads (American).
All switches and hose fittings for R134a are Metric.

I bought entire new 95 R134a system; evaporator, condenser, dryer, hoses, switches.
Took months to gather all the correct stuff.
Took about a week of wrenching to get it done.

The most difficult part to get was the hose set the attaches to the compressor. No one makes it and the hoses out there are all built incorrectly.

Here are my build/problem threads
http://zr1.net/forum/showthread.php?t=30711
http://zr1.net/forum/showthread.php?t=30748

Ccmano · 03-31-2021

Quote:

Originally Posted by XfireZ51

I don't think Marc will have a problem with me posting his response to my inquiry re:134a. Looks a bit less involved than we may have believed. I will swap out the high side switch, just in case, but otherwise...

Hi Dominic,

The OE o-rings and switches are compatible with R-134a refrigerant. I have a GM service bulletin advising that. Only three things are needed. 8 oz. of PAG oil, service port adapters for R-134a and the refrigerant.

When installing a new compressor, it's a good idea to install a new filter/dryer and a new filter/orifice.

Best regards.

Marc

Please note this post. I've done exactly this on several cars including my current car. I usually change the orifice valve too. AC works perfectly!
H

mhobtr · 03-31-2021

I don't know about the high pressure switch but the low pressure switch is adjustable by turning a screw between the terminals.

The low pressure cut off is 2 lbs lower for R12 than R134a but the switches are the same. If you buy a new replacement, it will be set for R134a.

I'm still running R12 and I discovered this when I had to replace a faulty LPS.

07-20-2020	#21
-=Jeff=- Join Date: Jul 2007 Location: Bartlett, IL Posts: 7,169	Re: R-12 to R-134 conversion What do the fittings look like for the high side and low side, that will help to determine R-12 or R134a __________________ 1990 Corvette ZR-1 #1051 Watson Headers (2" Primary) - Flowmaster Cats - Borla Catback Late Model IH - Plenum Coilovers - 4.10s Custom Interior NCM Lifetime Member #978

07-20-2020	#23
-=Jeff=- Join Date: Jul 2007 Location: Bartlett, IL Posts: 7,169	Re: R-12 to R-134 conversion Gotcha as for the orifice tube. Which are listed for the car? __________________ 1990 Corvette ZR-1 #1051 Watson Headers (2" Primary) - Flowmaster Cats - Borla Catback Late Model IH - Plenum Coilovers - 4.10s Custom Interior NCM Lifetime Member #978

07-20-2020	#24
XfireZ51 Join Date: May 2007 Location: Chicagoland, IL Posts: 9,708	Re: R-12 to R-134 conversion All I did was replace O-rings, new PAG oil in compressor and different fitting for evaporator/dryer. __________________ [SIGPIC][/SIGPIC]Former Membership Chairman Former ZR-1 Registry - BOD 1972 Corvette 4speed base Coupe SOLD long time ago 1984 Corvette Z-51/4+3 SOLD 1992 Corvette ZR-1 Aqua/Gray #474 SOLD 1992 Corvette ZR-1 Black Rose/Cognac #458 2014 Honda VFR Interceptor DX

07-20-2020	#26
PhillipsLT5 Join Date: Aug 2005 Location: Scottsdale, AZ Posts: 2,452	Re: R-12 to R-134 conversion Years ago I installed a severe climate tube in Hot PHX with R 12 worked fine, blew 38-40 degree air out, dont know about the color

03-31-2021	#27
Matt B Join Date: Jan 2021 Location: Beautiful Bavaria Posts: 523	Re: R-12 to R-134 conversion As mentioned in another threat I my R-12 was drained during import into Europe. So now I need to switch to 134a as R-12 is illegal here... However, reading through this threat left some confusion. Appreciate if someone can add some clarity on the following: - switches: it was said that R-12 high pressure switch will not operate correctly but can be adjusted by turning the adjustment screw 1/4 ccw. So no other switches or adjustments other than that needed, correct? - PAG oil: I'm an A/C dummy so sorry for that stupid question (I know there are no stupid questions but I think this one is...) but the oil is not only inside the compressor but the entire system, right? So, I need to remove the compressor from the car, drain it and also flush the rest of the system? However, in an case I can re-use the OEM compressor with no further modifications? - Orifice tube: do I need to swap it? If so, Rockauto lists a variety: GM GENUINE 155151 {#03033879, 3033879, 3033879OEM} ACDELCO 155754 {#19189768, 88919511} - "OE replacement" ACDELCO 1550120 {#19189841, 89032868} - "Optional Automatic Adjusting Orifice Tube For Normal Climates Under 105 Degrees" ACDELCO 1550122 {#19189843, 89032872} - "Optional Automatic Adjusting Orifice Tube For Severe Climates over 105 Degrees" Which one is correct? Germany is not a super hot place, however does the "hot climate version" maybe improve the cooling power? I heard that the ZR has it's limitations here... Will I need a remover tool to get the job done or will needle nose pliers work? I already have a new dryer on the shelf which I will install including some fresh O-Rings. Now I need to collect the rest and plan the actual work. Sorry for all these questions but as spare parts are sometimes hard to come by over here I became very careful to not destroy things due to stupid mistakes __________________ ZR-1 #638/1991

03-31-2021	#28
Subfixer Join Date: Sep 2018 Location: Groton, CT Posts: 384	Re: R-12 to R-134 conversion I converted my 92, but it was not easy. R12 switches and hoses are SAE threads (American). All switches and hose fittings for R134a are Metric. I bought entire new 95 R134a system; evaporator, condenser, dryer, hoses, switches. Took months to gather all the correct stuff. Took about a week of wrenching to get it done. The most difficult part to get was the hose set the attaches to the compressor. No one makes it and the hoses out there are all built incorrectly. Here are my build/problem threads http://zr1.net/forum/showthread.php?t=30711 http://zr1.net/forum/showthread.php?t=30748 __________________ 1992 ZR1 #442, 2 tops, White, White, Haibeck 415, 3.90 gear, Coilovers 2018 Audi RS5, 2.9 V6 Twin Turbo, Auto, Black, Black 2021 Audi Q3, 2.0T, 8 spd Tiptronic, Navarro Blue metallic, Pearl Beige

03-31-2021	#30
mhobtr Join Date: Apr 2016 Location: Birmingham, Alabama Posts: 60	Re: R-12 to R-134 conversion I don't know about the high pressure switch but the low pressure switch is adjustable by turning a screw between the terminals. The low pressure cut off is 2 lbs lower for R12 than R134a but the switches are the same. If you buy a new replacement, it will be set for R134a. I'm still running R12 and I discovered this when I had to replace a faulty LPS.