AC Condensor

[lookforjoe]

Thanks Karl. I did actually add an air guide under the spoiler that tucks under the condensor & up to the base of the rad, so air has to come from further forward. I'm going to experiment with raising the condensor an inch (to clear the spoiler) and move it forward about the same. I need to figure out some sort of airguide/seal along the verticals as well, perhaps.

 

[kmead]

Should have known, you are a pretty thorough individual :thumbsup:

Do you think there is actual mechanical transfer of heat from the condenser to the radiator (and vice versa) and thus an air gap between them will reduce it? Perhaps a couple of pancake fans in between the two?

 

[LarryC]

I was wondering about conductive heat transfer, too

I don't have a lot of factory air set ups to look at, but it would be interesting to see if there is a "standard" separation that is commonly used. What is the separation on your wagon?

 

[lookforjoe]

The standard gap on Volvo setups is about 1.5" - mine is greater because the stock intercooler is gone, and my Howe radiator is 3" core.

I do in fact have over an inch between the two, it was just tapered at the base. I thought more about the overall setup, and Tony's earlier comments, and the fact that the VW rad doesn't sit at the stock angle, it was tipped further back.

So, I modified the lower mounts, and cut the back of the SerpentAuto Spoiler, to allow the condensor to angle further forward & down. The rad now sits at about the same angle as a stock rad, perhaps slightly more vertical.

Previously, that lower hose was pressed up against the leftside fan

I just have to bypass the temp sensor used to activate the AC fan, as I want it to come with the AC, NOT when the system is already under stress...

The last thing, I forgot to reverse the wiring on the AC fan (since it's inf front of the condensor, instead of behind), so if it was coming on on Saturday's drive, it was pulling instead of pushing - not good!

 

[lookforjoe]

Should have known, you are a pretty thorough individual :thumbsup:

Do you think there is actual mechanical transfer of heat from the condenser to the radiator (and vice versa) and thus an air gap between them will reduce it? Perhaps a couple of pancake fans in between the two?

I think the problem is more the restriction of air flow to the rad caused by the larger condensor - the fin condition is not the greatest, so it may well be inhibiting the normal flow through the rad. The air gap just helps to prevent excessive heat transfer from one to the other. I have a similar situation on the wagon, where I had to make sure there was at least a minimal air gap between the header & the wastegate.

 

[lookforjoe]

Fixed the connections to the AC fan to reverse flow (push instead of pull)

Added airguides to either side of the rad to force air through the condensor first - with the grille in place, they are pushed inward to align with the condensor edges

AC vent temp today

coolant temp

with the AC off, the gauge stays just over center, where it has been. With the AC on, extended idling will still bring the gauge up around 215ºF - checking with a laser temp I have 185ºF at the T/stat housing outlet, 168-172ºF at the housing inlet. Obviously the temp is rising, but it seems the gauges just aren't reliable?

 

[TonyK]

Interesting post.

Just a few questions since I returned today from FFO 2012.

The stock Fiat fans move a lot a air, how do your fans compare in CFM's.

Also at the expansion valve how hot is the inlet compressed gas? Is there frost just after the valve? Possibly you have a duff, new expansion valve?

The temps you are posting seem a bit high, but then again the gas pressure could also be a bit too high. What are you using for refrigerant? I still would suggest to use 2 cans of Dura Cool and then top off with R134a. The temps you are getting equal what I was getting or with the stock system, I possibly was getting lower temperatures than this as well.

I purchased a small 10" x 19" condenser and the Jag dryer as well. I am guessing here, but think that the hottest part of the rad on the top is allowed to obtain as much cold air for a reason and not through the condensor. I am wondering if it is too restrictive and blocking air flow through the rad. Have you tried driving the car with the AC off and seeing if the engine temps are now higher?

When I get around to installing the new Aux condenser I will place it in front of the stock condenser and it will be in the cooling circuit after the stock condenser where it will pick up the coolest air in the flow stream and only aid in dropping the compressed gas temperature.

Since you have more area in the condenser your charge pressure should be lower. Just a note here is when I turn on the AC the condenser fan does not start. As the pressure builds and temperature of the liquid gas increases the fan comes on and the pressure drops 50 PSI. At 2000 rpm or so the pressure is 360 PSI with the fan AC condenser fan being on.

Thanks for the post. I am not sure when I will attack my project, but I have the parts sitting and ready.

TonyK.

 

[LarryC]

TonyK brings up some good points.

There may be a good reason that the stock fan makes a lot of noise (more CFMs), so I have been a little leary of the need to go to an aftermarket fan.

But your experiment is exceptional. These are excellent engineering tests and progress is being made! Meanwhile, I have been doing some research. Sorry for the long post below. It's a data dump.

It is frustrating since the coolant temperatures you are getting seem to have risen. It looks like in order to the get the necessary condenser dimensions, which is at least 200 sq in (and 220-240 would be even better), it requires pretty much covering the radiator with a condenser. Your experiments thus far are really valuable and suggest that the radiator is near its capacity, and that anything that further blocks the airflow to the radiator increases the coolant temperature. It is easy to see why Fiat installed such a small condenser. But with R-12 you could get away with a small condenser. The other possibility is that the particular condenser is restricting flow, too close, at the wrong angle, or restricted in some way. Without some way to measure airflow through the radiator with and without the stock condenser, it’s difficult to know what the CFM should be.
At this point maybe a realistic target would be to (a) keep the condenser large, but increase the flow of air though it; or (b) only slightly increase the condenser size, maybe with a more efficient modern design.

Realizing that an option somewhere in between is probably, like usual, more realistic, I have been researching OEM condensers to see if there is something out there that we can adapt easily. What I learned was the fact that after about 1990, the condensers all became much bigger than will fit in the X. Because of the need to stay between 250 - 300 ci, condensers with heights less than 11 inches are rare. Which tells us something we may not want to hear. For the compromise route (slightly bigger condenser, but not too big) the mid-80s is where the interesting condensers are.
My list of close fits with 8 and 6 MOR fittings on the pass side:
-82-86 Camry (25 x 11 x 1) 275 ci (not confirmed, the parts houses list something different!)
-82 Prelude (22.75 x 11 x 1) 250 ci
-84 Rabbit convertible (21 x 11 x 1.5) 346 ci
-82 Porsche (18.5 x 11 x 1) 203 ci
-81-83 Toyota pickup (21.25 x 9 x 1) 191 ci
-90 Wagoneer 6cyl (27.5 x 10 x 1) 275 ci
-81 Scirroco (22.5 x 11 x 1.5) 371 ci copper
-88 Scirroco (27.5 x 11 x 1.5) 454 ci copper

From this little search it looks like the Rabbit condenser, followed closely by the 81 Scirroco, has promise at a wopping 346 ci and 370 ci respectively, although it is unusual in that it is 1.5 inches thick. I don’t know whether that is significant enough to lower the flow or not. Unusual nonetheless. But, to be honest, even the Toyota Pickup condenser would be bigger than the 154 ci condenser on the X. Actually it would be slightly larger than the condenser size increase recommended by VA for 134a conversions while not entirely covering the radiator. Hmmmm.

I wish Vintage Air offered a Superflow condenser in the 9 x 24 size. That could be a good compromise: Increased efficiency and slightly increased size. But they only list a 12x 20-24. I don’t think that a 12 tall condenser could be made to fit. They are only 0.8 in thick though.

 

[lookforjoe]

The pair of 10" fans I have installed pull 1250CFM's each. They are wired to come on with the coolant temp sensor in the lower hose.

Don't recall what the spec on the small 7" push fan is. That one is wired to the AC circuit, and since the AC & Rad fans share a ground, they both come on around 200ºF (engine coolant temp). I left the wiring as it is.

I checked the High/Low side pressures today - 25low 290high, with ambient temp in the 90's, a vent temp of 65º, and a gauge temp of around 210ºF after idling with the AC on for 15mins. Refrigerant is R134a. The pipes & the expansion valve are wrapped in butyl.

The equipment I used to charge the system & check pressures doesn't have an accurate scale, so I put in about 1.5lbs of R134a (gradually). At that point, the high side pressure rose to about 290 as indicated, so I stopped adding freon. There were still bubbles in the sight glass, but I don't think that's unusual with R134a.
A neighbouring station has a new setup, so I may draw it down again & refill to the specified 2.5lbs & see what happens. As it is, I have no idea how much freon is actually in there, just that the vent temp & pressures seemed reasonable.

If I let the car sit & idle (no AC), the engine temp stays a tick over 190ºF according to the gauge. Temp at the t/stat housing outlet is around 180ºF. inlet around 165-170ºF. So, I presume the overall flow through the condensor to the rad must be OK, it's the radiant heat off the condensor when the AC is on that must impacting the engine temps at idle.

I think shifting the angle of the rad closer to stock did help.

 

[TonyK]

Supper Flow Condensor

Here is a picture of the Super flow condenser that I just had shipped to me. Looking at the spare hoses that I have in the basement, I will order a #6 180 degree fitting to point everything in the right direction. Although the condenser is a 10x18" unit it measures the coils at about an inch less that that. I would like to paint it black on one side at least to make it less noticeable. I have other things on the go and cannot attend to this for at least a month. So it may be a winter or spring project.




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TonyK.

Grimsby Ontario Canada.

 

[lookforjoe]

Tony, that looks like a decent size.

I emptied & recharged the AC today, on a different machine that has an accurate scale.

Pressures with system off

Only had about 1.3lbs in it.

recharged with 2.1lbs (R134a apparently fills at about 20% less)

No bubbles to speak of in sight glass.

Ambient temps

AC on - moving it will drop to 60º at these ambient temps.

Engine Temp

AC works fine. Engine temp will still climb if idling extensively.

I tried several things:

Removed the rear plastic panel on the engine cover. No Change.

Re-installed the FI fan (I had removed it when the headers were installed, since the shroud does not fit) and wired the thermoswitch to ground instead of via the OP switch, so it now runs when engine (bay) temp exceeds about 220ºF. No Change.

Reworked the air intake to move the filter outside the car, incase the extra heat soaking would make a difference. Car ran better, for sure with the lower air intake temps, but made no difference to idling w/AC on. Used a bunch of Volvo intake plumbing of course.

(K&N Xtreme in this pic - I swapped it out for the smaller K&N after this run)

SO, the only thing I can see really that's left is that the stock water pump just doesn't have enough push/pull at idle to keep the system happy with the AC on. As I said before, engine temps as displayed on the gauge are steady with NO AC, it ONLY a problem with the AC on, in these high ambient temps.

I think I may have to add an electric pump like Bob. I don't want to have to worry that the motor will overheat when I get stuck in highway traffic on a hot day, it's bound to happen.

 

[TonyK]

Dura Cool.

I think you could get another 10 degrees lower if you filled with 2 single pound cans of dura cool. Then topped off with 134a. I was getting better temperatures than this with a stock X engine and car with Dura Cool. 35 degree differential is possible. Since you have a larger condenser that would also help the low end temperature.

What RPM was the engine running at? ( 1500?) You could still go about another 50 PSI higher on the output side of the compressor if at 1500 rpm. If that is idle then it should be okay. Low side should be between 20 and 30 PSI.

Nice equipment.


TonyK.

Grimsby Ontario Canada

 

[LarryC]

TonyK, where did you get a 10x18?

Does VA have that. They only list a 12" wide. 10 " would just about fit.

 

[budgetzagato]

Missing data...

What is your idle speed with and without the A/C?

My Bertone liked an idle at 1000rpm to help move coolant at idle, especially with A/C. The stock idle step-up valve was barely adequate I found.

 

[TonyK]

Condenser supplier

See this link.

http://www.nostalgicairparts.com/ac/painted-black-aluminum-109.php

Nostalgic is a very good vendor to deal with they also sell the expansion valve.

I thought I ordered a Black condenser, but I know I have a non painted one.

If it was 15 square inches bigger then it would be a good alternative.

I am going to put it in series and almost double the condenser area.


TonyK

Grimsby Ontario Canada.

 

[lookforjoe]

What is your idle speed with and without the A/C?

My Bertone liked an idle at 1000rpm to help move coolant at idle, especially with A/C. The stock idle step-up valve was barely adequate I found.

My AC step up is great - I did away with the factory crap (because it couldn't provide a stable idle speed, nevermind the hokey AC stepper valve) in favor of the old Bosch Constant Idle System used on 240turbos.

Tony - I'm not going to do the condenser over - I have sufficient surface area with my combined unit. I just have to figure out an aux pump setup like Bob's to assist in coolant flow.

It just seems that once the tipping point is reached the stock (cooling) system has a really hard time recovering (unless you turn off the AC, run higher rpm's, drive with engine cover open, etc.). I'm trying to get as trouble free a setup as I can manage.

 

[TonyK]

I agree on the taxed cooling.

A long time ago I realized that performance improvements meant more cooling required. Pump to impeller clearance is one that should be at the min. tolerance. With a 40-80 camshaft, headers and MegaSquirt, dual rads is the route I went and it works well. But, that car does not have AC.

The Stock X has no cooling problems with the AC running, so a little more condenser will not be an issue. On the down side the car in comparison to my modified X is a bit of a dog in performance, but is a cool ride.

TonyK.

Grimsby Ontario Canada.

 

[LarryC]

This has been a great fact gathering thread and much has been learned

..by me, at least. I agree that the cooling system is o.k. for stock arrangements, which is why I appear to have no problems in that area.Even on 100 degree days my X maintains 190, only going over just before the fan kicks in, at which point the temperature drops rapidly. It will be interesting to see if the auxiliary condenser TonyK is planning impedes cooling any noticeable amount since it is clear that airflow is the main requirement.

I like the 10x18 or 11x20 condenser. Even that is larger, by about 20-30 percent, than the stock condenser. So I am considering using that in lieu of the stock condenser, if it fits reasonably.

TonyK, are the MOR fittings on the stock condenser 6 and 8? Or would new hose fittings need to be made to use the Nostalgic condenser?

 

[TonyK]

Fitting size.

The fitting size on the Stock and after market condenser is #6 on the out put and #8 on the input. But the X condenser has the fittings pointing to the rear of the car. The aftermarket condenser has them facing to the left or to the right depending on how you mount it.

So, if you look at the last picture I posted in this thread I show the fittings required to connect the after market condenser to the X hoses. If you go the after market Super Flow route, then making 2 short hoses from #6 and #8 hoses would be required. If you need more details let me know as the lines from the X will require Male Insert O ring fittings and the hose would then connect to standard Male O ring fittings to the condenser.

TonyK.

 

[lookforjoe]

Did some more experimentation today. I'm pretty sold on an aux water pump, but in the mean time I did some testing with what I have available - which meant another Volvo part

I wanted to see whether having better airflow through the engine bay would have any benefit to my problem.

I took a V70 fan shroud & fan, modified the shroud to fit over the engine cover. It's only velcro'd in place, so easy to remove.

power supply hooked up to feed from starter to alternator to allow for the heavy draw.

fuses & relay. Only using the high output circuit.

I tried using the FI cooling fan thermoswitch, but it doesn't turn on soon enough, so I switched it for an Fiat 87º rad fan switch. I haven't bolted it down, so I could move it around a bit, to find the optimum spot.

As it is now, the cover fan switches on when the gauge reads about 205-210ºF

AC vent temp

I let the car idle with the AC on for about 20mins. The temp did not rise above this. So, having high CFM pull through the engine bay does make a significant difference.

Looks ugly as sin, though :hmm2:

Wiring