there isn't a forum for the a/c so i went with "cooling:". i need to replace the factory a/c condenser coil in my 91 firebird. there are plenty for sale with a quick google search. however i wanted to check in and see if there is an upgrade than anyone here has used? my a/c worked fine before i broke it a couple of weeks ago. it gets really hot here so the a/c is a must. so has anyone used an upgraded a/c condenser coil? if so what and where?

 

I don't have an answer for you but this is a very good question, Evil. All of the available, new condensers are china made so I'm suspicious of the quality. However, I think a non-leaking china condenser is better than a leaking/damaged OEM condenser.

My AC system in my '87 IROC still has a non-leaking OEM condenser. The AC system had been converted to R134a some time in the past. A lot of my system will be replaced as I'm in the middle of an LS7/T56 Magnum F swap right now. I'd love to go with a more efficient, modern, parallel flow condenser but the fact that they're chinesium keeps me away. Hopefully someone with experience with an aftermarket condenser can give us a good news update.

BTW, what went wrong with your OEM condenser?

 

id head to the local junk yard and get one from a new vehicle.
its not hard to make some mounts, and anything form a new vehicle will be better than a near 40 old design that was made for R12.
Or even go onto vintage air and get one of their condensors. I dont know where they are made, but ive used porobbaly a dozen of them, and theyre strong and built well... probbaly china as well

 

yes, there is a new style condenser (parallel flow) that will cool r134 better. this topic was brought up recently, @houstonvett mentioned this. Perhaps a 1994 F-body would work. I looked at this closer and you would have to add a some lines to reach the pipes as the 3rd gen pipes are not in same location as 4th gen, but not completely out of the question to do. I've done much harder things. The next question is will it fit? Don't really know, didn't dig into it further.

 

I wouldn't be so quick to do this and here is the reason why: if the car you're pulling the condenser from had a bad AC system, i.e. compressor or hose failure, these debris will clog a parallel flow condenser and you cannot flush a parallel flow condenser. I'd be leery of using a used parallel flow condenser unless you know it's history.

I like your idea of using Vintage Air condensers. Even if they're chinesium, they're probably pretty good.

 

Rockauto sells parallel flow condensers that fit 3rd gens.

 

I bout a big bottle of the GM oil, I’ll stay with GM stuff

 

This all the way. Have used them, good stuff right there.

 

When I look up condensers for a 1987 350TPI Camaro, Rockauto shows four different brands.

1. OSC 3231

2. SPECTRA PREMIUM 73231

3. GPD 3231C

4. FVP CON3231

Which one(s) did you use?

 

Normally I'd go with the four seasons or FVP, but neither is available. The GPD looks to be your best bet, and it is indeed a parallel flow style.

 

Thank you, Berlinetta. This could be helpful information for others reading this thread.



In my case, I've got a perfectly good, non-leaking OEM condenser. Granted, its not an R134a efficient, parallel flow condenser but it is OEM.

I do have experience with using an old school, R12 condeser with a converted R134a system. Years ago, I ordered a 1991 Mustang GT from Ford. After owning the car for about 15-16 years, the leaking system (leaking evaporator) was using up my stash of R12. It was time to convert. I did all my research and I did a good conversion. The AC cooled really well driving down the road at speed (40F) but at stop lights, the vent temp would increase toward about 60F. I'd been wanting to convert the OEM, mechanical radiator to a very powerful Lincoln MKVIII electric fan. This was a popular swap for Foxbody guys back in the day.

I got one from a local junkyard and installed it. I already had a 130 amp alternator so I had plenty of juice to power that hurricane fan. After installation, the fan pulled so much air through the condenser and radiator that my AC vent temperatures stayed at 40F even at long red lights. It made me a believer in quality, powerful electric radiator fans.

Fast forward to today and that same OEM Ford AC condenser is in my 1991 LS376/480hp/Tremec T56 Magnum swapped Mustang coupe. I'm using a Holley Dominator controlled, OEM, pulse width modulated C7 Corvette radiator fan. With the amount of airflow that fan pulls through the old school condenser, my AC is sub 40F even in Houston heat. I'm thinking that I'll have the same performance using my 1987 IROC's OEM condenser. I'm going to make my brand new Gen6 Camaro, 18" OEM PWM fan fit.

 

This is exactly the issue with the R134A retrofits with the OEM condenser. I had the same issue with mine years ago with R134A. OK while driving, warmer when sitting.

R134 needs either the parallel flow condenser or more airflow across the condenser. You solved the issue on your Fox body with more airflow. Could probably do the same on a thirdgen.

The other thing people do is use a slightly smaller orifice tube. It creates more of a restriction and increases the head pressure and temperature of the refrigerant in the condenser, increasing heat transfer. Makes the compressor work harder though. There are other threads about this, but I believe the go to is the Ford red tube.

I put in a new Spectra AC condenser in mine. It physically fit fine, but have not yet installed the lines and charged the system, so can't yet say how well it works.

 

I've read this before about changing out the orifice tube. I never understood why nor did I write down the recommended color to go with. I'm not really sure that I like the idea of the compressor having to work harder. It's probably a non-issue but I still don't like it.

Like I posted previously, I'm planning on using a huge, 18" diameter 6th gen Camaro, PWM fan that's made by SPAL in Italy. It'll pull a lot of air through the condenser and radiator.

 

With R134a the compressor works harder anyway. The R134a builds more pressure for a given condensing pressure. Changing the orifice tube makes the difference between not cooling well and cooling well. Generally speaking I have had great results in just about every GM with a Ford Red 0.062" tube.

 

Exactly what Fast355 said.

A/C system lesson for those who are interested in how it works and why the orifice tube change is effective here.
The attached pressure-temp chart for both R-12 and R-134A describes is nicely. The chart is showing the condensing temperature of the refrigerant at a given pressure. Condensing temperature is the temperature at which the refrigerant will change phase from liquid to gas or the other way around. In a vapor-compression refrigerant based A/C system, like in our cars, the compressor takes the low pressure/low temperature refrigerant gas and increases pressure to a high pressure/high temperature gas. That high pressure gas goes through the condenser where heat is removed at constant pressure, cooling the refrigerant down below the condensing pressure, turning the refrigerant into a high pressure liquid. This phase change of the refrigerant from a gas to a liquid releases a significant amount of stored energy (heat) to the atmosphere. That high pressure liquid then goes to the evaporator but just before entering the evaporator, goes through the orifice tube, which is just a small hole that creates a restriction to flow. That restriction creates a pressure difference from one side to the other and the downstream side of the orifice tube, is the low pressure side. The drop in pressure causes the liquid refrigerant to evaporate, or change phase back to a gas and that phase change absorbs a significant amount of energy (heat) from the evaporator. The low pressure gas goes back to the inlet side of the compressor where it is pressurized again and the cycle repeats. The only reason an A/C system like this works is because of the properties of phase change at different pressures and temperatures in the condenser and evaporator, which allow heat to be moved from the cabin to the outside air.

So, if you look at the pressure-temperature chart, you will see the condensing temperatures at various pressures for both refrigerants. In a typical system, you will see about 28-30psi on the low side (evaporator) and about 200psi on the high side (condenser). If you look at the chart on the low side, 30 psi equals about 32 degrees for R-12 and 35 degrees for R-134A. Small difference, a little noticeable as a slightly higher discharge air temp at the vents in the car, but not a big deal. This is why the recommendation to adjust the lower pressure cut in/out switch a couple of psi lower is there, so the evaporator is allowed to get down to the same temperature as it was designed for with R-12.

The real difference comes in the high side, and that's why you see issues when the car isn't moving. At 200psi, the condensing temperature of R-12 is 140ish degrees, but R-134A is 130degrees. So that means if the A/C system is operating at the pressures it was designed for with R-12, but filled with R-134A, the condenser needs to drop the temperature of the refrigerant 10 more degrees in order to cause the refrigerant to change phase from gas to liquid, and it was not designed to do that. It's close enough to "work", but not work well.

There are 3 things that can be changed to make R-134A work correctly in an R-12 system.

1. Move more air across the condenser to extract more heat from the refrigerant and drop the temperature. Bigger fan does this, as does driving down the road, which moves more air than the fans.
2. Increase the surface area of the condenser in contact with the outside air. The newer design parallel flow condensers possibly do this, but I haven't done any analysis to prove or disprove, nor do I care to.
3. Increase the pressure difference between the high side and low side of the system so that the high side runs about 230psi for this example and the low side around 28psi. This will increase the refrigerant temperature in the condenser from 130 degrees to the design temp of 140 degrees and now the condenser will work as it should. So, in this example, the original R-12 system would have been designed for a 170 psi differential pressure (200-30) while the R-134A system would need to operate at a 202psi differential pressure (230-28). The smaller orifice tube is what will do that. The extra 30psi the compressor sees shouldn't be an issue for a healthy compressor. If the compressor is on it's way out, it will probably kill it in a little quicker.

So that's why the smaller orifice tube works for R-134A conversions.

 

OK. It sounds like I need to get a Ford, red .062" orifice tube.

Transam, very, very informative explanation!

I'll be purchasing a brand new Genuine Sanden SD7B10 (7176) mini compressor

I'm in a discussion with a member on a 2nd gen Camaro forum concerning compressors. He thinks that this Sanden 7176 is too small to adequately cool in high heat like Houston, TX. Physically, it's what I need to fit in the low mount location (passenger side) that I'm planning. On the other hand, it only displaces 6.1 cu in or 100cc according to the SD Compressor Service Guide

What do you guys think?

BTW, I'm realizing that I hijacked the OP's thread.

 

In my experience at lower engine rpm and around town, the SD7H15 even with the smaller 4.25" pulley is inadequate with a GM evaporator core setup in DFW although it does do better out in the panhandle in the one blinking redlight town areas where most of the time the engine is singing 2,500-3,000 rpm. I swapped the SD7H15 for a Four Seasons HT6 replacement 210cc 10 cylinder in my 97 Express and have cold a/c even at idle now. Personally I would figure out how to make a GM V7 work.

 

Thank you for posting your experience. Your results are the same as someone else posted on the 2nd gen website, nasty Z28.com. Inadequate cooling at low speeds with the small, 7176 compressor.

What kind of fan do you have pulling air through your condenser/radiator? As I mentioned in post #11, I had 1991 Mustang cooling issues at idle with the OEM mechanical fan with my R134a conversion. When I switched to a powerful Lincoln MK VIII electric fan, my vent temperatures stayed the same at idle and at speed.

 

Had a Duramax 9 bladed clutch fan and a pair of 11" electric pushers. Has plenty of airflow, just not enough compressor displacement. Just swapping compressors made the air ~20F colder at the center vent at idle.

 

Sounds like you had good condenser/radiator air flow. 20F colder at idle through the center vent is significant. 20 degrees colder at idle is what I experienced going from my Mustang's inadequate, OEM mechanical fan to the high powered, Lincoln MKVIII electric fan.

I really wanted to low mount my AC compressor on my LS7 swapped IROC project. I've got a high mount compressor on my LS3 swapped Foxbody coupe. It was easier to mount, has a lot of room, easier to work with AC hoses, etc. However, all of that is in the way when I need to deal with plug wires, plugs and so on. In addition, to me, its a cleaner look when everything is down low. However, I think that I'd rather suffer through all of that instead of suffering through Houston summer heat and 60F vent temperatures at idle speed!

 

This was with the bigger SD7H15 after I put it on the L31 350 swapped into my 87 G20. Totally inadequate on my 97 Express and borderline functional on the 87 G20. I still find it lacking in stop and go or slow moving traffic. Luckily it spends most of its time on the open road, not in town.