Hot Rods How do I choose an A/C condenser size & Fan?

In my 48 International Harvester pickup, I have an aluminum radiator and I have about 20 in of width for the condenser in front. How do I choose a size? Is larger better or is there some factor for choosing? I have a typical Sanden compressor and the evaporator unit is under my dash.
Also, I have an electric fan behind the radiator, the pull type. Do I need an additional fan in front of the condenser?
My engine is a 327 ci and the existing fan cools it fine.
Appreciate any help.
Bob
http://www.bobsretrophobia.com/

 

Put the biggest condenser you can fit no farther than 1/2" away from radiator...Present fan may work well enough but at worst you will need a larger one..I prefer a mechanical fan, just my pref..

 

I didn't have room for a regular belt driven fan so I chose the largest that would fit and set it up as a pull type. I can add a pusher electric fan in front of the condenser but I don't know if that is advisable to have two fans?

 

As stated use the largest condenser and electric fan you can fit. Do not use a pusher fan as it only restricts airflow. The only puller electric fan to use is a SPAL. Don't believe any CFM claims from other manufacturers as they are all BS. They don't use SPAL fans on Ferraris for nothing.

 

I have a small (10" or so) SPAL pusher fan mounted down in the corner of my condenser, with a flex fan & shroud puller behind the radiator. Does not reduce cooling under normal conditions & when it's really hot out I kick on the pusher & it really helps.

 

I've read that a puller fan is more efficient than a pusher. Something about the turbulence around the blades, so stick with the biggest puller you can fit.
There are formulas for evaporator and condensor size, but I think it would be home sized units before you would notice any efficiency gains or losses.

 

This is the way I would do it,,pusher fans are a waste of time and money. HRP

 

I installed the largest aluminum condenser I could get on my 1955 Chevy. I had it made to fit perfectly in front of the cross flow radiator.

I was told by the AC guy that my condenser is too efficient!!!

Since I am running a tri-nary switch the electric fans will pulse at idle and it sounds really annoying until the engine temp gets warm enough to keep the fans running constantly.

As I understand it...the tri-nary switch protects the system from excessive high or low system pressures plus it will automatically operate the electric fans as needed

The problem I have is that even when idling the system will tell the fans to kick on and as soon as the fans begin to operate and draw air through the condenser the condenser is so efficient that the refrigerant pressure will rise so rapidly (about three seconds) that the fans will kick off....then about three seconds later the fans will kick on again and it will do a three second pulse while idling. Naturally while on the open road the fans never kick on.

Does anyone know how to fix this??? I thought of only wiring one fan to the AC switch but leave the two fans for the radiator cooling.

 

Has anyone else had that problem with the fans pulsing like that?

 

""Does anyone know how to fix this??? I thought of only wiring one fan to the AC switch but leave the two fans for the radiator cooling.""

That means the AC pump is cycling too..I would run the one fan continuously when you put the air on, let the AC compressor do the cycling as needed and have the second fan come on if the engine needs it but both fans have to come on when the AC is off..Let the compressor cycle because one fan is on just as if a mechanical fan was in use, constant air flow when ac is on..

 

That's what I was going to say - wire one fan to run whenever A/C is on and the other to engine temp.

I did not realize the auxiliary pushed fan on my car was a waste of time & money. I thought it was a good way to keep from overheating on 100-degree days and to get my A/C work better. Guess I'd better take it off & go back to watching my temp gauge rise at red lights.

 

Thanks Seb and Dave...I will try that and report back.

Bill

 

Your condenser condenses high temperature/pressure gas into a liquid think condensation on your windshield here. The pressure does not rise when the fan comes on it, when the fan comes on it would just condense more rapidly, uh makes more liquid. The high pressure liquid evaporates in the evaporator, this is caused by heat transfer by the surrounding environment, the liquid absorbs heat. You feel cool when this happens, the truth is that there is no such a thing as cool just the absence of heat. That said the old heating and cooling guys used to say it makin' cold if it was working correctly. LOL

Most factory AC units have the fan come on continually when the AC unit is in use. I think that what you are experience is the pump cycling, this is probably cause by too much liquid returning in the suction line and a more efficient evaporator is probably going to be your solution. Or perhaps a better fan to blow more hot air over the evaporator. before you change everything around try turning your fan on high and se if it doesn't help.