AC and Trunk Combo

I've been told that it works better with the trunk in place. I cannot however, verify this as my condenser is in front of the radiator.

Thanks for the input.

Arizona summers aren't here yet but maybe I will get the data logger and temp probes out soon and put post some info.

John

#3590

Further to Forest's comment above; DeTomaso designed the rear condenser/fan assy. to work with the trunk in place. Also, make sure you have a Binary switch in your A/C system, that disengages the compressor clutch if the system pressure goes too high or too low.

The air conditioning condenser fan is designed to pull air in from the rear of the car and recirculate it back out to the rear. The truck insert is designed to allow the air to flow in that direction. With the trunk liner out, that fan is going to be working against all of the air pressure that is developing from under the car. You could always just test the car with the trunk liner inserted and with it removed and see which method works best. I have wondered what would happen if someone was to install a pusher fan on the condenser and then drove the car without the trunk liner. It would seem that you would be able to increase the air flow, but I doubt that it would work very well with the trunk liner installed. I have no way of testing that theory in my Pantera because the condenser is in front of the radiator. That modification seems to work very well in 100 degree Arizona weather.

When I was upgrading the ac in my 71 pb I noticed the condenser fan was several  inches from the face of condenser

my experience with radiators is that the fan should be about 1/2 inch from the fins for best efficiency, therefore I pushed the fan several inches closer to the condenser by installing long mounting bolts. I have no definitive testing to prove an improvement but it seems there should be a little

FWIW, When I converter my AC to R134a in 2003, I fabricated a shroud to fit the parallel flow condenser and added a 1,200-cfm fan that does sit closer to the condenser than stock setup. AC still blows cold, but on a blazing hot day, I wish I had more air coming out of the two little vents in the middle of the dash.

@davidnunn posted:

Further to Forest's comment above; DeTomaso designed the rear condenser/fan assy. to work with the trunk in place. Also, make sure you have a Binary switch in your A/C system, that disengages the compressor clutch if the system pressure goes too high or too low.

Where is this switch located?

i moved the condenser to the front of the car, ac works  great! car runs hot though

There wasn’t one from the factory. Pantera’s tended to rupture A/C hoses or blow the ends off hoses, if the car was driven at high speed for a long period with the A/C on. System pressures would go too high without any safety mechanism being in place. A binary switch will disengage the compressor clutch if pressures go too high or too low.
The easiest way to install one is to put it in the drier. Most driers have an unused port that the switch can be installed in. If you’re building a new system, you can also get in-line binary switch ports.

@davidnunn posted:

There wasn’t one from the factory. Pantera’s tended to rupture A/C hoses or blow the ends off hoses, if the car was driven at high speed for a long period with the A/C on. System pressures would go too high without any safety mechanism being in place. A binary switch will disengage the compressor clutch if pressures go too high or too low.
The easiest way to install one is to put it in the drier. Most driers have an unused port that the switch can be installed in. If you’re building a new system, you can also get in-line binary switch ports.

I just redid the whole A/C system and got it charged… here is what I just ordered… I think I can install it without evacuating and recharging…

I mounted mine in the drier as David mentioned. I ran the wiring up to the A/C relay under the dash to interrupt the system.

Dennis

@Bell3156 posted:

i moved the condenser to the front of the car, ac works  great! car runs hot though

I’ve never used a front mounted condenser but I will next time! I would think the fans you use would be critical. It is possible to stuff two 14” fans behind the rad and brushless fans tend to be more powerful, although not cheap. PWM fan speed control helps too. Also, if you have dual fans in a shroud, make sure they turn on at the same time, unless you have a baffle between the fans.

i have the Ron Davis radiator from the Quellas and a PMW control that brings both fans on at 60% when the ac is on but the car goes from 180-220 in a few minutes city driving in az with 85 outside temp

putting an oil cooler on place of the condenser. having one made for the space with a 9" or two 5" spals with PMW control

bell3156 -

Are you using the standard fans from Ron or brushless with the PMW?  Who's doing your oil cooler and PMW ?   I'm also in Phoenix and looking for a little bit more cooling capacity.   I've limited my city driving as much as possible since it's right at the edge of my current cooling capacity.   I don't currently have an issue since it's on jack stands while I upgrade the brakes. 

Just got back from Palooza Sunday with the rear trunk installed over the rear mounted condenser.

AC was plenty cold with the outside temp around 94-100F.  I'm using Quella's 3 speed fan in the dash.  Worked great although having more vents would be better.

Car ran 190F on the freeway for the 6.5hour trip at 80MPH most of the time.  Temps would creep up to ~220F or so when exit freeways or sitting in PHX traffic.  It didn't boil over when I parked it, so I consider that a success.

Not sure how it will fair when sitting in traffic with AC on and 115F outside but that will be the next test.

John

#3590