87 Overheating with AC On

[raidoman]

87 with 71k original miles, just had AC converted to R134 and it cools great but now it runs 190's with no AC jus tlike it has for the last 15+ years I've owned it. It would run a little warmer - low 200's with old AC. Now it will hit 240. All fans come on as they sohould, plenty of coolant. There is some bearing noise from the compressor at low rpm so I know it is getting tired but still is cooling great. Any ideas out there? Thanks for any input.

 

[boomdriver]

87 with 71k original miles, just had AC converted to R134 and it cools great but now it runs 190's with no AC jus tlike it has for the last 15+ years I've owned it. It would run a little warmer - low 200's with old AC. Now it will hit 240. All fans come on as they should, plenty of coolant. There is some bearing noise from the compressor at low rpm so I know it is getting tired but still is cooling great. Any ideas out there? Thanks for any input.

The 134a tends to have more heat to dissapate in the condensor than the r-12 system and the 134a needs more of a condensor to be equally effective, so that translates into more heat to trade away in less space, so its less efficient.
All that means, is that the condensor runs hotter than your radiator. When the a/c is running, even though the fans are ON, they are pulling the super-heated air from the condensor straight into the radiator, so it has a poor heat exchange now. It will not cool the engine unless the air-flow is less heated then the temp of the coolant. If the air-flow is the same or hotter, there will be no cooling or heat exchange. The system is designed to pull fresh air around the condensor to supply the radiator, but the use of the fans sends the hot air from the condensor into the radiator. There is simply no place else that it can go. If someone came up with a baffle or duct to route the condensor heat elsewhere,and allow fresh air directly to the radiator, that would be a priceless aftermarket part.

People like to say "turn ON the a/c to cool your motor down"......maybe so on a r-12 system. But, when you convert to 134a, the exact opposite is true.
Mine does the same thingas yours and for me to have a decent heat exchange in the radiator I'll have to get a racing radiator that has 100% more heat exchange (2 or 3 row) if I want to run the a/c in traffic. I can turn the a/c off and within 2 minutes my temp drops 10 degrees or more.
Be sure that your nose is clean and has not scooped up some trash thats blocking the radiator. Pulling the top shroud is as much a maint item as oil changes.

 

[Roasted Garlic Chicken]

pull the radiator out and clean out the junk in between the condensor

 

[raidoman]

Thanks for the clarification on R 134 an how it functions. I had cleaned out the nose and looks like it's new high capacith radiator time. Living in Memphis, AC is a way of life so I guess now I have to hunt down a rad.

 

[Roasted Garlic Chicken]

Thanks for the clarification on R 134 an how it functions. I had cleaned out the nose and looks like it's new high capacith radiator time. Living in Memphis, AC is a way of life so I guess now I have to hunt down a rad.

i just bought this one, every bit as good as a dewitt, and dropped 30`40 degrees

Aluminum Radiator Corvette 1985 1986 1987 1988 1989: eBay Motors (item 390204225294 end time Jun-12-10 14:20:32 PDT)

very affordable and top notch construction and design do for it

 

[boomdriver]

i just bought this one, every bit as good as a dewitt, and dropped 30`40 degrees

Aluminum Radiator Corvette 1985 1986 1987 1988 1989: eBay Motors (item 390204225294 end time Jun-12-10 14:20:32 PDT)

very affordable and top notch construction and design do for it

RGC..
Your temps really dropped that much?
Thats exactly what I am looking for. I looked at those same radiators about 3 mts ago and ask the crowd here if anyone had used a 2 or 3 row all alum and all I got was suggestions that I change T-stats or telling me that I've already got an aluminum.....you get my drift.
I was very curious about that price and what you got for the money.

I'm glad to hear firsthand from someone that KNOWS by way of experience with the product.

I wired my condensor fan to run all the time so the condensor stays cooler, but just as I described above, now my radiator temps shoot up in traffic and stay there until either a/c is off or cruise at freeway speeds for 10 minutes....but the ambient is so high that exchange is poor. The new radiator is as good as bought after hearing that they DO work well.

 

[Roasted Garlic Chicken]

you have to trim the rubber supports on the top and bottom, i sloted the upper shroud at the hose so i can remove the shroud in the future without opening the system to clean the junk in the front., I use water wetter one bottle and around 10% antifreeze.

I live in LA and it's is going to get hot, My motor is a built 383 and is pushing alot of horses, I need the peace of mind that I won't fry my motor and my money...

go for it will tale you 4-5 hours of fun work!

 

[raidoman]

Thanks again for the great info. Will order one soon as I have time to install. I have a Z-52 car so will need the trans cooler hookup.

 

[Roasted Garlic Chicken]

comes with a cap, low sensor, drain plug and trans cooler all factory fittings

 

[boomdriver]

you have to trim the rubber supports on the top and bottom, i sloted the upper shroud at the hose so i can remove the shroud in the future without opening the system to clean the junk in the front., I use water wetter one bottle and around 10% antifreeze.

I live in LA and it's is going to get hot, My motor is a built 383 and is pushing alot of horses, I need the peace of mind that I won't fry my motor and my money...

go for it will tale you 4-5 hours of fun work!

COOL !

I'm in Tex currently but I am from LA area...in fact, this motor was rebuilt in Pt Hueneme with the machine work/boring done by Fains in Oxnard. My motor is bored with other enhancements, so it generates way more heat than the solid brass radiator can get rid of. I'm running a brass because it has metal tanks and holds more water than the stock unit. Back there along the Ca coast, that was plenty good. I lived 2 blks from Ventura harbor, and before that it was Newport Beach, so the car had an easy life with an occasional road trip to Palm Springs or Vegas..Even then, it ran cooler because the desert heat is dryer. The worst conditions were trips to Simi Valley where the moisture met the desert heat and spelled misery....alot like here. I sure got spoiled living by the beach.

Since then the car has lived in Az and now Tex and its hotter than lil sister around here...Neither me or the car enjoy it much. This Gulf Coast stuff with 70% humidity is BS.

My shround is already trimmed around the return neck, so trimming the blocks ain;t a big deal.

Did you go with the 3 row? or 2?

 

[Roasted Garlic Chicken]

2 rows, just buy the one on the link, any more rows and the fit will be tight

 

[MBDiagMan]

Nice looking radiator.

I converted my 88 to 134 about 15 years ago. I never noticed any difference in cooling and I'm in Texas. I drove it about 250 miles Sunday with some of that being stop and go traffic. I never saw anything over 200 degrees at any time and that was with the a/c going full blast.

I have flushed the cooling system and replaced the coolant religiously every other year since I bought the car in the early nineties.

 

[raidoman]

87 Rad

Thanks for the great pics. My 2 row from that link arrives tomorrow so I will have a weekend project. thanks again for the input.

 

[boomdriver]

I'm ordering mine this coming week as well...
Also looking into a better or new condensor. May as well do it right...

After lots of reading on the radiators, 2 row vs 3 and fee-bay and everything else, this link offers the best deal for the dollar.
I have my doubts that a 3 row could even have any air flow with the very limited space we have. It would need a pusher as well as a sucker fan and we just cannot do that.

I have often thought of a different condensor design that would allow a pusher of maybe 12" or a little more, to be mounted. Engine cooling is ALL about heat-exchange and the more air that flows across the more cooling surface, the better, faster that exchange will be. Like the OP, my motor is built, and cost me more money than I can throw at it again, so running at 225 with the performance drop-off at hi temps is just not acceptable, neither is life on the Gulf Coast without an efficient a/c system...

Can;t wait to get that new radiator ! ! Thanks for the tip !

 

[MBDiagMan]

I'm ordering mine this coming week as well...
Also looking into a better or new condensor. May as well do it right...

After lots of reading on the radiators, 2 row vs 3 and fee-bay and everything else, this link offers the best deal for the dollar.
I have my doubts that a 3 row could even have any air flow with the very limited space we have. It would need a pusher as well as a sucker fan and we just cannot do that.

I have often thought of a different condensor design that would allow a pusher of maybe 12" or a little more, to be mounted. Engine cooling is ALL about heat-exchange and the more air that flows across the more cooling surface, the better, faster that exchange will be. Like the OP, my motor is built, and cost me more money than I can throw at it again, so running at 225 with the performance drop-off at hi temps is just not acceptable, neither is life on the Gulf Coast without an efficient a/c system...

Can;t wait to get that new radiator ! ! Thanks for the tip !

From what I've seen you are making a good choice with the above radiator. Don't worry about the 2 row business. These aftermarket radiators are made different from the ones used when our cars were new. This two row radiator will probably exchange more heat than a 3 or even 4 row of old.

Also, what year is your car? Mine is an 88 and it has both a pusher and a puller fan.

I replaced my a/c condensor last year with a stock replacement and even though I am in Texas, my a/c is capable of making a Polar Bear scream for mercy. This is even though I converted it to 134 many years ago.

 

[vetteoz]

I have a Z-52 car so will need the trans cooler hookup.

Z52 was only a suspension package.All C4 autos have the trans cooler in radiator

 

[Curious George]

The 134a tends to have more heat to dissapate in the condensor than the r-12 system and the 134a needs more of a condensor to be equally effective, so that translates into more heat to trade away in less space, so its less efficient.
All that means, is that the condensor runs hotter than your radiator. When the a/c is running, even though the fans are ON, they are pulling the super-heated air from the condensor straight into the radiator, so it has a poor heat exchange now. It will not cool the engine unless the air-flow is less heated then the temp of the coolant. If the air-flow is the same or hotter, there will be no cooling or heat exchange. The system is designed to pull fresh air around the condensor to supply the radiator, but the use of the fans sends the hot air from the condensor into the radiator. There is simply no place else that it can go. If someone came up with a baffle or duct to route the condensor heat elsewhere,and allow fresh air directly to the radiator, that would be a priceless aftermarket part.

People like to say "turn ON the a/c to cool your motor down"......maybe so on a r-12 system. But, when you convert to 134a, the exact opposite is true.
Mine does the same thingas yours and for me to have a decent heat exchange in the radiator I'll have to get a racing radiator that has 100% more heat exchange (2 or 3 row) if I want to run the a/c in traffic. I can turn the a/c off and within 2 minutes my temp drops 10 degrees or more.
Be sure that your nose is clean and has not scooped up some trash thats blocking the radiator. Pulling the top shroud is as much a maint item as oil changes.

I have a '92 convertible (and automatic to boot) and when I converted from R-12 to R-134A, I did not see any difference in coolant temps nor any other "anomalies". Typically, 134A systems are designed with a parallel flow condenser for maximum system efficiency. When converting a GM system (orifice tube type) to 134A the single biggest improvement comes from using a slightly smaller orifice tube assuming the rest of the conversion was done properly. For example, the factory o-tube in my '92 was .072". By using a Ford blue o-tube (.068") you can get better performance (cooling) from the R-12 designed system and old school condenser.

CG

 

[boomdriver]

I have a '92 convertible (and automatic to boot) and when I converted from R-12 to R-134A, I did not see any difference in coolant temps nor any other "anomalies". Typically, 134A systems are designed with a parallel flow condenser for maximum system efficiency. When converting a GM system (orifice tube type) to 134A the single biggest improvement comes from using a slightly smaller orifice tube assuming the rest of the conversion was done properly. For example, the factory o-tube in my '92 was .072". By using a Ford blue o-tube (.068") you can get better performance (cooling) from the R-12 designed system and old school condenser.

CG

Mine seems like it has always collected more heat from the condensor and effected the engine temp. we're on the 3rd compressor, 2nd radiator and 5th major a/c service, and its behaving as it always has. This car has well over 1/4 million miles on the chassis. Closer to 300K....
The problem is that it generates more heat for whatever reason cannot exchange it once operating temps get up to 225+. The a/c adds to the problem. With ambient temps @90 or below,(60% humidity) its fine.It hangs around 200. Thats comfortable. Everything works well. It runs fine. Go much above that and it just cannot rid itself of the higher temps and all systems suffer.Once it hits 230 it tends to stay at 230. Thats why I'm interested in the new hi-performance radiator...to have better heat exchange. Its gonna get hot...the trick is getting rid of the heat and since it all ends up in the radiator thats where the more efficient big aluminum radiator comes in.

Now I'm wondering....

The orifice had to be ordered from the local parts place and they were TOLD that I needed the orifice for 134a, since both are available but the 87 was an r-12 system.
Mine is very sensitive on the charge....an oz too much and cooling goes down. Too little and cooling is inadaquate. Meaningless since I will be draining and making certain that they gave me the correct orifice. If I'm REALLY lucky, I still have the plastic package with its label, stored in the box of crap for a/c service...treasure hunt this weekend.

 

[boomdriver]

From what I've seen you are making a good choice with the above radiator. Don't worry about the 2 row business. These aftermarket radiators are made different from the ones used when our cars were new. This two row radiator will probably exchange more heat than a 3 or even 4 row of old.

Also, what year is your car? Mine is an 88 and it has both a pusher and a puller fan.]

Mines an '87. The 2nd cooling fan was an opt....HD cooling. All that meant was a pusher fan that was/is not shrouded, and comes on as a last chance before meltdown. Because the main air-flow to the radiator is around the condensor, the pusher fan is mounted several inches ahead of the condensor so it can generate a small amount of airflow to go thru the baffles and into the radiator. Since mine was very inefficient without any kind of shroud, and it self destructed by tossing a blade, I mounted a (16") directly to the condensor to keep it cool in extreme conditions. Smoke test show similar air moving thru to the radiator, although heated.
The a/c does not have to be on for my pusher to operate, its on a switch in the dash. This arrangement seems to have very little effect on the engine temps, running on not. The pusher just does not have enough pressure to help the engine temp. It helps the condensor temp, but the air-pressure is pretty well absorbed by the condensors tight veins. I've tried other sucker fans and NONE are as efficient as the stock GM unit. Not even close.

 

[Curious George]

Mine seems like it has always collected more heat from the condensor and effected the engine temp. we're on the 3rd compressor, 2nd radiator and 5th major a/c service, and its behaving as it always has. This car has well over 1/4 million miles on the chassis. Closer to 300K....
The problem is that it generates more heat for whatever reason cannot exchange it once operating temps get up to 225+. The a/c adds to the problem. With ambient temps @90 or below,(60% humidity) its fine.It hangs around 200. Thats comfortable. Everything works well. It runs fine. Go much above that and it just cannot rid itself of the higher temps and all systems suffer.Once it hits 230 it tends to stay at 230. Thats why I'm interested in the new hi-performance radiator...to have better heat exchange. Its gonna get hot...the trick is getting rid of the heat and since it all ends up in the radiator thats where the more efficient big aluminum radiator comes in.

Now I'm wondering....

The orifice had to be ordered from the local parts place and they were TOLD that I needed the orifice for 134a, since both are available but the 87 was an r-12 system.
Mine is very sensitive on the charge....an oz too much and cooling goes down. Too little and cooling is inadequate. Meaningless since I will be draining and making certain that they gave me the correct orifice. If I'm REALLY lucky, I still have the plastic package with its label, stored in the box of crap for a/c service...treasure hunt this weekend.

134A systems do seem to be somewhat sensitive to the amount of refrigerant used. When charging a system, you should use a scale, accurate to within 1oz. (or less) in order to charge the system correctly. Also, do not use or fall for those "hybrid" refrigerants claiming cooler temps than 134A, they usually raise system pressures and cause problems in the long run. Also, do not use the refrigerant / sealer junk, especially in a TXV type system.

CG