I've been curious about what could be done to improve the performance of my A/C system after the swap to R134 which did not perform very well compared to the R12 that was in the system before the compressor locked up. I purchased a 3 core aluminum radiator and figured when I get ready to install it I should look into incorporating a larger condenser. What I found instead is a more efficient condenser called a parallel condenser that is more characteristic of the radiator design. It is said to be 1/3 more efficient than the tube and fin design. It also appears it may allow better air flow through the core for more efficient air saturation of the radiator core behind it.

If anyone else with A/C knowledge and experience has more to contribute to the subject please do so. Some have had pretty good performance with R134, my experience stems from a few months in Miami Florida during the summer where it performed so poorly it was barely worth turning the A/C on. I have since flushed the A/C system and installed a late model A/C compressor that came with the 3900, that I understand will require an additional inline modification to fit a sensor or two to meet the requirements of the Fiero system, and have not charged the system yet as a result.

I could also use some dimensions for the maximum area available for a condenser since I'm not able to get to my car to take the measurement myself, as the site I've linked to below basically offers a range of sizes to be custom fitted and would like to install the largest that can be accomodated.

Parallel flow condensers

http://www.ackits.com/merch...tegory_Code=Parallel

Here is a write up on an install in a Jaguar that netted 5-6 degree cooler temps.

http://bernardembden.com/xjs/pcond/index.htm

[This message has been edited by Joseph Upson (edited 12-21-2009).]

I cannot imagine anything wrong with a parallel condenser, it sounds like a great idea. What I don't understand is why you would need one. I am curious why your A/C did not work effectively in FL. Is it because of the higher humidity? My A/C has some new parts such as a HR-6 compressor, std condenser (stock style) and accumulator. I suspect that it is not quite as frosty as when it used r-12 but even with 134a it will freeze me out of the car if I have it above "low" fan during 115 degree "dry" heat. That is after it has had about 5 minutes to cool off the heat soaked interior. I am also using the VOV instead of the stock orifice tube but I really don't know if that is making much difference or not. Good luck in your quest for great cooling.

Charlie

It sound to me like you have an unresolved problem, rarely does a condenser cause a problem. did you do the flush yourself? If your old compressor locked up, you need to replace everything other than the evaporator, lines and condenser, they can be flushed, but orifice tube or expansion valve, compressor, accumulator all need to be replaced. if you run your ac system without replacing these components and flushing the other stuff you can almost guarantee you gonna trash that new compressor.

I tend to agree with optsnoopy and AmericanMuscle that you may have other issues preventing you AC system to perform satisfactorily. I have done the R12 to R134 conversion on my '86 GT like many. The AC system performs very well. As mentioned, even at low settings there are times when it gets a bit too cold for my liking. Oh, the weather here in South Louisiana is similar to what you have in Miami, I'm sure.

Bottom line, I would suggest you first sort out the existing system before investing in a parallel condenser. Becuase, I fear is you do not you will not get the results you are expecting. The entire system needs to be functioning properly, not just the condenser.

Good luck in sorting out your AC system issues.

Hold it. I'm not blaming the condenser for anything, I'm just considering the upgrade. I have not used my A/C system since the system flush and compressor change due to the engine swap. Prior to that it had been running for a few years with R134 after the compressor lockup so I have not performed a complete system analysis to get to the bottom of the cooling performance issue which shouldn't be affected by the failed compressor due to the number of years gone by. I will be replacing the dryer which was removed and flushed out and will take a look at the evap core. At the time of the flush they were not top priority because of the swap taking place and an incident that punctured an A/C line prompting me to do the flush due to the amount of time the system had been exposed to open air. For all I know the system refrigerant level could have been low, it's been some years now since the Miami incident and since I've actually had the system working. The main idea here was consideration of an upgrade that would result in colder temps and possibly more efficient air flow through the core. I'll restore the current system first before exploring the idea further since you guys are getting so cold with it.

I understand and applaud your search for improved components, but with the Fiero's tiny cabin, I don't think any upgrades are necessary provided the system is working properly.

However, if you need to purchase a new condenser anyway, why not give it a shot? As long as it is sized appropriately to perform at least as well as the stock one, it should work fine.

I'm not an HVAC expert, but I fail to see how slightly improved efficiency in the condenser will impact the cold air out of the vents. Here's hoping an expert while chime in.

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1988 Fiero GT
Custom Corvette / MR2 electro-hydraulic power steering
17" rims covering up 11.25" rotors with Cadillac Calipers & drop spindles
2009 Secretary
Cleveland Fieros
Cleveland Fiero Club

quote Originally posted by TG oreiF 8891: I understand and applaud your search for improved components, but with the Fiero's tiny cabin, I don't think any upgrades are necessary provided the system is working properly. However, if you need to purchase a new condenser anyway, why not give it a shot? As long as it is sized appropriately to perform at least as well as the stock one, it should work fine. I'm not an HVAC expert, but I fail to see how slightly improved efficiency in the condenser will impact the cold air out of the vents. Here's hoping an expert while chime in.

The purpose of the condenser is to cool the refrigerant down after compressing, if you increase the cooling efficiency of the condenser resulting in even cooler refrigerant temps, you should also note cooler temperatures from the vents as indicated in the swap thread for the Jag I linked to. The same is true for turbocharging, as the intake charge temps get cooler, the exhaust temps are also cooler. I'm not an expert that's just my understanding.

[This message has been edited by Joseph Upson (edited 12-21-2009).]

My understanding is that the gaseous refrigerant is compressed in the compressor to high pressure which creates heat (just like an air compressor does) then the condenser removes some of the waste heat and condenses (thus the name) the gases back to a liquid state. The cooling is produced when the liquid refrigerant expands in the evaporator into a gas again.

So I guess assuming everything else is equal, a more efficient condenser would loose more heat leading to cooler refrigerant temperatures going to the evaporator. The cooler refrigerant would then cool further than normal in the evaporator. Sounds correct to the uneducated (me), anyways. If I'm even close to correct, that would definitely lead to cooler temps at the vents.

Just for the fun of it, while your car is sitting at idle with the A/C on, spray a little water over the condenser coils and (if the ambient temps were really hot that day) you will feel a significant change in the air temp coming out of the vents. That is why our radiator fan operates when the A/C is selected on. I imagine that if a parallel condenser is more efficient at removing heat from the freon than our stock condensers are, you should be able to tell the difference at the air vents. My guess is that it will be most noticeable during very hot days at idle rpms and low vehicle speeds. Nothing wrong with that for sure. JU, if you try it can you report back?

Charlie

quote Originally posted by TG oreiF 8891: So I guess assuming everything else is equal, a more efficient condenser would loose more heat leading to cooler refrigerant temperatures going to the evaporator.

Only partly correct. If all the refrigerant is condensing and the final temperature of the liquid leaving the condenser is within 20 degrees F of ambient (i.e. the outside temperature), a "better" condenser is going to provide very little improvement in cooling, if any.

The OEM A/C system is, if anything, oversized for the small Fiero cabin. IMHO, your time and money would be better spent figuring out why your existing system isn't working correctly.

quote Originally posted by Marvin McInnis: Only partly correct. If all the refrigerant is condensing and the final temperature of the liquid leaving the condenser is within 20 degrees F of ambient (i.e. the outside temperature), a "better" condenser is going to provide very little improvement in cooling, if any. The OEM A/C system is, if anything, oversized for the small Fiero cabin. IMHO, your time and money would be better spent figuring out why your existing system isn't working correctly.

Not wanting to get into to much technical A/C system operation. I see where you're going in regards to system performance relative to temperature differential in that every degree drop in temp at the condenser will not result in an equal degree drop in temperature at the vent.

However, although the stock system is apparently sufficient with both refrigerants, R134 does not cool as well as R12 in an old system which was the complaint with its application in place of R12. Apparently this complaint is what brought about the parallel flow condenser which many if not all new cars are probably using today. According to the tech at the company I linked to above, the old tube and fin design works best with R12, the parallel flow design works best for R134. We discussed temperature differential but still could not arrive at a conclusion that a ~1/3 more efficient condenser for R134 in place of the old tube and fin design would not result in a noticeable difference in temperature at the vent. The second link to a swap upgrade resulted in 5 deg cooler temps at the vent using a parallel flow condenser that is smaller than the tube and fin model it was replacing.

It's not being viewed as a fix but more as an upgrade especially in the case of someone that has a condenser failure given the cost of an OE replacement at more than twice the cost of a universal parallel flow unit. An added feature that I mentioned previously is that it may allow air to flow through the core easier which will result in better radiator cooling from more air flow. This is significant for me because I want to maintain coolant temps on the low side of normal on a larger engine with a water cooled turbo that will add additional heat to the system, without the help of free coolant fan cycling.

It's an idea not a committed intent or solution to a problem with the system. I've already addressed the system with a flush and new style compressor in place of an original that might not have been pumping efficiently to build proper pressure levels since gauges were not connected for a test. I wouldn't attempt this modification without first testing my current system since performing maintenance on it. It is good to know about this option in the same sense that some have taken advantage of the radiator upgrade. It's just an idea for more adventure in creative mechanics.