AC Mods-Dual Evaporator-Larger Blower

[stormcrow]

Well, I've decided to do some experimenting with my AC system on the P-car. Because the stock system does not work properly, I am going to modify it.

The first thing I did was to increase the blower output. As you can see by the pics, I placed a 12v motor on top of the housing, and installed a larger blower wheel inside the housing.





With the increased blower capacity, the existing evaporator cannot handle the additional heat load across the coil, so the air coming out is at about 60F.

So, what I am going to do is stack two evaporator coils together and palce the blower on top of them. The pics show how the blower housing sets with both evaporators in place.





I am going to use the bottom of the box for the return air, and will modify the supply side with the addition of two more supply air ducts.

The pics shows the blower assembly, stacked coils and the blower in place. I will modify the coils so that one expansion valve will provide flow through both coils. I have another expainsion valve which can handle larger capacity if I needed it.

"

In additon, I purchased another coil which is a little bit wider/longer then the existing coil so that if stacking the coils won't work, I can modify this one to to add increased capacity as well.



So, as you can see by the pics, this is in the preliminary stages of assembly. Will keep you posted on the progress and outcome.

Steve

"A Porsche does more then just go fast in a straight line

[TurboBert]

Steve,
I'm looking fiorward to seeing how this goes. Have you also added more condensor(s)?

[PatrickB]

Hey Steve~ What P-car do you have?

[jtratza]

This could get interesting. Good luck Steve. If it works we all owe you a few beers and man of the year honors.

[stormcrow]

Patrick

I own a 78 911 SC Targa.

Steve

"A Porsche does more then just go fast in a straight line"

[PatrickB]

Best of luck Steve!!!!

I'm always curious to see how A/C upgrade experiments pan out....

Have you considered ES12a refrigerant (HC)? I purchased some, but haven't changed it out yet, as I want to upgrade the R/D with a Procooler at the same time... You might consider changing out the R/D if it hasn't already been done... I understand that can have a dramatic effect on the overall performance of the system if it's not functioning properly...

These topics have been beaten to death on this BBS, if you do a search for A/C!! Some very good technical commentary can be found here!!!

[Rodney Nelson]

I have always thought that is what was needed, a bigger blower. I am very interested to see what happens.

Could you please explain how the blower can overpower the evaporators? I don't understand how all of that works.

Thanks,

[Vonzipper]

I too am interested to see the out come


For some odd reason Tim Allen comes to mind??

[Rodney Nelson]

Where did the larger blower wheel come from???

[stormcrow]

Picked up the blower wheel off a pick up truck in the junk yard. They are pretty much the same size.

Steve

"A Porsche does more then just go fast in a straight line"

[stormcrow]

Well, I"ve been working on the evaporator and have the following report. As a first step, I wanted to see if I could get the existing evaporator to work by making some mods to it.

What I did was change the supply/discaharge to the coil. The factory coil has a single inlet that branches off to two of the supply tubes in the coil. The return side of the coil does the same. If you look at the pics of the existing coil, the inlet branches off to two outlets and the return does the same.

To modify the coil, I changed the inlet to a single inlet and single outlet. However, I changed the inlet side to the bottom of the coil where it will provide the coldest refrigerant



I reinstalled the coil and ran a test. With a outside temp of 85F sitting in the driveway, the temp on the supply air with R-12 came down to 55F. I didn't have an opportunity to take it for a drive because it was leaking at one of the U tubes In installed.

Next test was today. I removed the R-12 refrigerant along with the oil, injected 6 oz of PAG and four 12 ounce cans of R-134a. With the outside temp at 85F withe the P-car in the shade, the temp eventually cam down to 60F. It took a lot longer for it to drop then the R-12.

My next test is going to be with a R-12 replacement which is a drop in. I may not have to change the oil, but If I do, it won't be a problem.

Air flow across the coil was with the larger fan wheel when I did the tests. Tomorrow, I am going to call around and see what type of R-12 drop in I can get.

It looks like the R-12 or similar will get the temp to 50F without any problem. I will keep everyone posted on my progress.

[scottb]

Originally posted by stormcrow
It looks like the R-12 or similar will get the temp to 50F without any problem. I will keep everyone posted on my progress. [/B]

Where are you measuring the temps...at the center vent or ambient inside the car?

[stormcrow]

Measuring the temp from the center vents in the car.

Steve