R-12 to R-134 conversion - Page 2 - ZR-1 Net Registry Forums

XfireZ51 · 06-18-2018

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

jss06c6 · 06-18-2018

Excellent information.. wouldn't expect anything less from Mr. Haibeck!

Sent from my XT1585 using ZR-1 Net Registry mobile app

S.hafsmo · 07-03-2020

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

This is correct? You do not need to replace expansion valve, compressor, condenser, pressure switch etc.?

Is there any way to tell if the system is already converted?

Drier and orifice recommended, I see.

WARP TEN · 07-03-2020

Quote:

Originally Posted by S.hafsmo

This is correct? You do not need to replace expansion valve, compressor, condenser, pressure switch etc.?

Is there any way to tell if the system is already converted?

Drier and orifice recommended, I see.

Yes. Marc once showed me the GM service bulletin on the subject back in the late '90s when I had my '93 converted. And I think that the fill valves are different for the R-134a than the R-12 but not certain; others know better. --Bob

-=Jeff=- · 07-03-2020

If I recall fill for R134a is maybe 90% of R12

mhobtr · 07-03-2020

The low pressure switch is the same but there is a small screw between the wire terminals that is turned to adjust the low pressure cutoff.

IIRC the low pressure cutoff is 24psi for R-134a and 22psi for R-12 but you need to check the service manual to be sure.

Ccmano · 07-03-2020

I can tell you that back in the day when I was doing these we only replaced the orifice valve (R134 specific), installed an R134 adapter, evacuated the system, added PAG oil and recharged with R134. A they always worked just fine. I believe any orifice valve you get today will be R134 compatible.
H

viper107 · 07-03-2020

i have just allways screwed on the 134a fittings to the hoses and shot the system, blows ice cold if the system is healthy, never changed nothing

jss06c6 · 07-05-2020

Old thread..

I replaced my condenser (source of leak), compressor (R134 version), dryer and orifice tube. No pressure switches were changed.

I changed the compressor to a NOS unit "while I was in there". Dryer swap good practice. Put in 8 OZ PAG 100. Vacuum for 2 hours. Tight as a drum 24 hours later.

System took 1.83 lbs R134A. Blows cold with no issues.

Sent from my SM-G950U using ZR-1 Net Registry mobile app

Ccmano · 07-20-2020

Looks like I need to replace my condenser. I plan to replace it and the dryer/accumulator. The compressor was replaced a few years ago. Can't tell if the system is running on R12 or R134a. I plan to recharge it with R134a. Does 4.5oz of PAG 100 oil (per the manual) sound correct since I'm not doing the compressor?
H

06-18-2018	#11
XfireZ51 Join Date: May 2007 Location: Chicagoland, IL Posts: 9,708	Re: R-12 to R-134 conversion 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 __________________ [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

06-18-2018	#12
jss06c6 Join Date: Aug 2015 Location: Magnolia, Texas Posts: 884	Re: R-12 to R-134 conversion Excellent information.. wouldn't expect anything less from Mr. Haibeck! Sent from my XT1585 using ZR-1 Net Registry mobile app

07-03-2020	#15
-=Jeff=- Join Date: Jul 2007 Location: Bartlett, IL Posts: 7,169	Re: R-12 to R-134 conversion If I recall fill for R134a is maybe 90% of R12 __________________ 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

07-03-2020	#16
mhobtr Join Date: Apr 2016 Location: Birmingham, Alabama Posts: 60	Re: R-12 to R-134 conversion The low pressure switch is the same but there is a small screw between the wire terminals that is turned to adjust the low pressure cutoff. IIRC the low pressure cutoff is 24psi for R-134a and 22psi for R-12 but you need to check the service manual to be sure.

07-03-2020	#17
Ccmano Join Date: Jun 2006 Location: Sparks, NV Posts: 2,852	Re: R-12 to R-134 conversion I can tell you that back in the day when I was doing these we only replaced the orifice valve (R134 specific), installed an R134 adapter, evacuated the system, added PAG oil and recharged with R134. A they always worked just fine. I believe any orifice valve you get today will be R134 compatible. H __________________ 90'ZR-1 #1461 Red/Black Ported Intake, Degreed Cams, OBX Headers & Exhaust, Fidanza FW, Secondary Delete, Custom tune, C6 GS Wheels. Sold 08 C6 Z51 Crystal Red Metallic Sold Vararam Intake, Tune, Sold 05 C6 Z51 Red/Black Sold 90'ZR-1 #1723 Black/Gray Sold but not forgotten 91' Z51 L98 White Vert. My First, you always remember your first. Sold.

07-03-2020	#18
viper107 Join Date: Dec 2019 Location: st louis mo Posts: 749	Re: R-12 to R-134 conversion i have just allways screwed on the 134a fittings to the hoses and shot the system, blows ice cold if the system is healthy, never changed nothing __________________ 95 admiral blue z(sold)/ / 93 ruby z(sold) 91 steel blue z/95 aqua z haibeck 510, 91 callaway 415 areobody #5

07-05-2020	#19
jss06c6 Join Date: Aug 2015 Location: Magnolia, Texas Posts: 884	Re: R-12 to R-134 conversion Old thread.. I replaced my condenser (source of leak), compressor (R134 version), dryer and orifice tube. No pressure switches were changed. I changed the compressor to a NOS unit "while I was in there". Dryer swap good practice. Put in 8 OZ PAG 100. Vacuum for 2 hours. Tight as a drum 24 hours later. System took 1.83 lbs R134A. Blows cold with no issues. Sent from my SM-G950U using ZR-1 Net Registry mobile app

07-20-2020	#20
Ccmano Join Date: Jun 2006 Location: Sparks, NV Posts: 2,852	Re: R-12 to R-134 conversion Looks like I need to replace my condenser. I plan to replace it and the dryer/accumulator. The compressor was replaced a few years ago. Can't tell if the system is running on R12 or R134a. I plan to recharge it with R134a. Does 4.5oz of PAG 100 oil (per the manual) sound correct since I'm not doing the compressor? H __________________ 90'ZR-1 #1461 Red/Black Ported Intake, Degreed Cams, OBX Headers & Exhaust, Fidanza FW, Secondary Delete, Custom tune, C6 GS Wheels. Sold 08 C6 Z51 Crystal Red Metallic Sold Vararam Intake, Tune, Sold 05 C6 Z51 Red/Black Sold 90'ZR-1 #1723 Black/Gray Sold but not forgotten 91' Z51 L98 White Vert. My First, you always remember your first. Sold.