A/C Recharge (Should I convert to R134a?) - ZR-1 Net Registry Forums

TexasZR1 · 03-23-2019

I have a 1990 ZR-1 with about 54k miles on it.

It's throwing a low refrigerant code on the AC unit. After resetting, it will blow cold air for a few minutes before throwing the code again.

Testing with a sniffer, it looks like the leak is the high side schrader valve. I have not detected leaks anywhere else, but I see some dusty oil around the fitting housing the expansion orifice. So I'm thinking I should go ahead and break the system open to replace the shcrader valves, o-rings and orifice. May as well replace the drier with the system open and replace all the seals where I break connections.

For the recharge:

- Any way for a technician to tell what refrigerant is in the system? It has a little charge of something in it. Not concerned about keeping, just want to know since it may affect what I recharge with?

Ideally, I'd be able to certain it had R12, and then refill with R12 ($125 for 1.75lbs from ebay).

Option 2 - Recharge with Alternate refrigerant

-What additional steps do I need to take to recharge with R134a? I've read the hoses made for R12 systems do not handle R134a well and will leach refrigerant through them? Is that true for the hoses used on a 1990, or would they have already been using hoses compatible with R134a at that point?

- What about Red Tek? Anything special I would need to do to recharge with this? It's cheaper than R12, and I can get it and charge it myself (i have a vacuum pump, would just need to have the existing refrigerant recovered at a shop).

I want to try to do as much of the work myself, but I don't want to mess anything up.

I've revived a few R134a systems before, but my third gen camaro was already converted when I purchased, and it's significantly less concerning how the job turns out (being that it's NOT a ZR1...)

Any advice appreciated!

WARP TEN · 03-24-2019

I had my '93 converted by Marc Haibeck. He said that GM sent out a bulletin that said you could just refill it with R134a (after a complete evacuation of old Freon) without changing components. There was more to it than that, of course, but Marc did mine using all the old components except the fill valve as I recall. I searched and could not find a reference on this but I know Marc has talked about it before. I would suggest a call to Marc to discuss it with him. He could likely put you on to the proper information and tell you what to look out for. --Bob

TexasZR1 · 03-24-2019

How does it cool given the undersized condenser and evaporator for r134a?

My 1991 camaro would cool fine, but would freeze over the evaporator core unless the fan was on max ac.

TexasZR1 · 03-31-2019

After some looking at mine, i noticed that the low side had a conversion fitting already. I guess the removed the high side one because of the leaky schrader valve? It has a old style cap on it. In any case, i ordered a conversion fitting set from FJC inc off of amazon.

The low side fitting is short enough that my r134a guages will fit! The parts house stuff is too long.

Thought i was all set, pulled a vacuum but it seemed top easy. Come to find out the guage pintle was sealing against the fitting housing when 'open'. Swapped a different schrader valve and it worked.

Pulling the vacuum now. Should be able to get charged this time.

A word of advice: connect the low side fitting to the guage before installing on the car and make sure you get flow through it.

TexasZR1 · 03-31-2019

A picture of the shorter fitting installed and the longer sitting on the canister.

03-23-2019	#1
TexasZR1 Join Date: Oct 2018 Location: Houston Texas Posts: 48	A/C Recharge (Should I convert to R134a?) I have a 1990 ZR-1 with about 54k miles on it. It's throwing a low refrigerant code on the AC unit. After resetting, it will blow cold air for a few minutes before throwing the code again. Testing with a sniffer, it looks like the leak is the high side schrader valve. I have not detected leaks anywhere else, but I see some dusty oil around the fitting housing the expansion orifice. So I'm thinking I should go ahead and break the system open to replace the shcrader valves, o-rings and orifice. May as well replace the drier with the system open and replace all the seals where I break connections. For the recharge: - Any way for a technician to tell what refrigerant is in the system? It has a little charge of something in it. Not concerned about keeping, just want to know since it may affect what I recharge with? Ideally, I'd be able to certain it had R12, and then refill with R12 ($125 for 1.75lbs from ebay). Option 2 - Recharge with Alternate refrigerant -What additional steps do I need to take to recharge with R134a? I've read the hoses made for R12 systems do not handle R134a well and will leach refrigerant through them? Is that true for the hoses used on a 1990, or would they have already been using hoses compatible with R134a at that point? - What about Red Tek? Anything special I would need to do to recharge with this? It's cheaper than R12, and I can get it and charge it myself (i have a vacuum pump, would just need to have the existing refrigerant recovered at a shop). I want to try to do as much of the work myself, but I don't want to mess anything up. I've revived a few R134a systems before, but my third gen camaro was already converted when I purchased, and it's significantly less concerning how the job turns out (being that it's NOT a ZR1...) Any advice appreciated!

03-24-2019	#2
WARP TEN Join Date: Apr 2007 Location: Lake Bluff, IL Posts: 2,040	Re: A/C Recharge (Should I convert to R134a?) I had my '93 converted by Marc Haibeck. He said that GM sent out a bulletin that said you could just refill it with R134a (after a complete evacuation of old Freon) without changing components. There was more to it than that, of course, but Marc did mine using all the old components except the fill valve as I recall. I searched and could not find a reference on this but I know Marc has talked about it before. I would suggest a call to Marc to discuss it with him. He could likely put you on to the proper information and tell you what to look out for. --Bob __________________ 2016 Long Beach Red Z06 #10281 "POPS Z" 1995 Polo Green #409 "WARP TEN"--Haibeck 350/510 package, 4.10s, Hurst, Stock Exhaust with QTP Cutouts --Sold but still running strong 1993 Quasar Blue #161 "HIL KING" --Sold but still running strong, now with more than 120,000 miles 1967 Marlboro Maroon/Saddle Corvette Coupe 300 hp/4-spd --Sold a long time ago ZR-1 Net Registry Founding Member #95 NCM Lifetime Member Favorite Quote--Attributed to Mickey Thompson: "Too Much Horsepower is Almost Enough"

03-24-2019	#3
TexasZR1 Join Date: Oct 2018 Location: Houston Texas Posts: 48	Re: A/C Recharge (Should I convert to R134a?) How does it cool given the undersized condenser and evaporator for r134a? My 1991 camaro would cool fine, but would freeze over the evaporator core unless the fan was on max ac. __________________ 1990 ZR1 #2184 BLK/BLK. Essentially stock. Plug-in Skip Shift Eliminator.

03-31-2019	#4
TexasZR1 Join Date: Oct 2018 Location: Houston Texas Posts: 48	Re: A/C Recharge (Should I convert to R134a?) After some looking at mine, i noticed that the low side had a conversion fitting already. I guess the removed the high side one because of the leaky schrader valve? It has a old style cap on it. In any case, i ordered a conversion fitting set from FJC inc off of amazon. The low side fitting is short enough that my r134a guages will fit! The parts house stuff is too long. Thought i was all set, pulled a vacuum but it seemed top easy. Come to find out the guage pintle was sealing against the fitting housing when 'open'. Swapped a different schrader valve and it worked. Pulling the vacuum now. Should be able to get charged this time. A word of advice: connect the low side fitting to the guage before installing on the car and make sure you get flow through it. __________________ 1990 ZR1 #2184 BLK/BLK. Essentially stock. Plug-in Skip Shift Eliminator.